# Upgrade to Calb batteries has begun



## ElectriCar (Jun 15, 2008)

For those who aren't up on this, I ordered 51 Calb SE200Ah cells in December for my S10. Paid up front with a check direct to Calb to get a discounted price. This upgrade should boost my trip capacity to around 100 miles from the current 30. It also saves 719 lbs, almost half the weight of the lead pack. 

The batteries arrived yesterday. Today I checked the voltages to see what I had. A sample of 12 cells yielded 9 at 3.265V, a couple at 3.266V and one at 3.264V, all within 2/1000 of a volt. Pretty amazing right there! I think that's close to fully charged for a Calb battery. 

Tonight I worked on the layout of the racks and a little on the conversion of power brakes to manual brakes. I'll be able to fit all 50 cells under the bed with room to spare. Battery 51 is a spare. I should have the brakes completed tomorrow. Had to get a part machined for the brake pedal to attach to the push rod. Eliminating the power brakes allowed me to drop 17 lbs and more importantly eliminate that God awful vacuum pump sound!


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## rwaudio (May 22, 2008)

ElectriCar said:


> For those who aren't up on this, I ordered 51 Calb SE200Ah cells in December for my S10. Paid up front with a check direct to Calb to get a discounted price. This upgrade should boost my trip capacity to around 100 miles from the current 30. It also saves 719 lbs, almost half the weight of the lead pack.
> 
> The batteries arrived yesterday. Today I checked the voltages to see what I had. A sample of 12 cells yielded 9 at 3.265V, a couple at 3.266V and one at 3.264V, all within 2/1000 of a volt. Pretty amazing right there! I think that's close to fully charged for a Calb battery.
> 
> Tonight I worked on the layout of the racks and a little on the conversion of power brakes to manual brakes. I'll be able to fit all 50 cells under the bed with room to spare. I should have the brakes completed tomorrow. Had to get a part machined for the brake pedal to attach to the push rod. Eliminating the power brakes allowed me to drop 17 lbs and more importantly eliminate that God awful vacuum pump sound!


I don't have experience with Calb, but that voltage on a TS or Headway would mean much less than 100% SOC. Fully charged after the surface charge disipates should be over 3.3V It's not like lead acid, in resting state the difference between 80% and 20% is very very small.


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## ElectriCar (Jun 15, 2008)

That's how they arrived but I'll figure it out once they're all connected and I can charge them for the first time. 

Finished the brake conversion today. Works like a champ so far. The pedal rests in the right place keeping the brake light off, something I was concerned may not happen. 

In the photos, you can see the plate that attaches to the firewall on an S10. The plate holds the push rod in place. The yellow thing has a hole in it where the rod goes through to the pedal. *To do this conversion you'll need to get those three pieces from a salvage yard or such.*

The photo of the pedal shows two studs. The smaller one on the bottom is where the brake switch activator connects and the old master cylinder rod used to connect. The thicker one above it is one I had machined for the manual master cylinder (MS). The hole was already there so I just needed the new stud. I had to coerce it a little to get it in with a brass hammer but it's a nice snug fit.  I then welded the back side to retain it.

Also shown is the power brake MS and the manual MS. Note the diameter of the cylinders. The power brake has a larger diameter cylinder but a short stroke. The manual one has a smaller diameter but longer stroke. The smaller diameter makes it easier to push the pedal. Relocating the push rod closer to the pivot point gives you more leverage which also makes it easier to push.

When finished I noticed it really opened that side of the engine compartment up. Lots more room there now with no vacuum apparatus and no brake booster. 

Now I have to finish the drawings for the battery boxes and install the Zeva Plus fuel gauge driver. It will operate the factory fuel gauge by counting amp hours installed and used. That will be a welcome change. NO MORE ERRATIC PAK TRAKR!!!!! The old pak trakr modules went into the trash. I wouldn't recommend that system at all. It's a good idea just not engineered properly.


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## DIYguy (Sep 18, 2008)

ElectriCar said:


> For those who aren't up on this, I ordered 51 Calb SE200Ah cells in December for my S10. Paid up front with a check direct to Calb to get a discounted price. This upgrade should boost my trip capacity to around 100 miles from the current 30. It also saves 719 lbs, almost half the weight of the lead pack.
> 
> The batteries arrived yesterday. Today I checked the voltages to see what I had. A sample of 12 cells yielded 9 at 3.265V, a couple at 3.266V and one at 3.264V, all within 2/1000 of a volt. Pretty amazing right there! I think that's close to fully charged for a Calb battery.
> 
> Tonight I worked on the layout of the racks and a little on the conversion of power brakes to manual brakes. I'll be able to fit all 50 cells under the bed with room to spare. I should have the brakes completed tomorrow. Had to get a part machined for the brake pedal to attach to the push rod. Eliminating the power brakes allowed me to drop 17 lbs and more importantly eliminate that God awful vacuum pump sound!


Glad to see ur off and running with your new batteries!  I checked a bunch of mine with a DVM. So far, they are all 3.299 or 3.298. I'll resurrect my thread soon. Sounds like we have similar upgrades going on to similar vehicles....


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## johnyac (Jan 30, 2011)

ElectriCar said:


> Paid up front with a check direct to Calb to get a discounted price. !


How much did the batteries and shipping run?


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## ElectriCar (Jun 15, 2008)

DIYguy said:


> Glad to see ur off and running with your new batteries!  I checked a bunch of mine with a DVM. So far, they are all 3.299 or 3.298. I'll resurrect my thread soon. Sounds like we have similar upgrades going on to similar vehicles....


Our meters likely are a little off from each other. Mine is fairly new but never been officially calibrated. Don't need that anymore for what I do. 

This afternoon I finished the dimensions of my boxes. I'm planning for 1/2" polyisocyanurate insulation with the foil on one side. It's pretty rigid and is R4, better than the pink foam insulation at home stores.

Here's a photo of my 200Ah cell. These things were a little larger than I expected.


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## ElectriCar (Jun 15, 2008)

Got a new game plan for the pack install thanks to a friend. He restores old cars and is restoring a '40 Ford pickup to convert. So his idea is to build ONE big rack between the cab and the rear end to hold all 50 cells. Beats the heck out of building 3!

It's a radically different approach to the norm but I like it. It's going to eliminate more heavy cables between racks AND the hinged bed. No more lifting that thing up! His plan was to build the rack high enough to clear the drive shaft and rear end travel. This way it will take up the entire area between the frame rails from just behind the cab to right near the diff. Naturally it will protrude through the bed a few inches but he's going to build a box around the area with an air gap between the battery box top and new bed extension. 

I'll have to give up some bed space and hauling ability but the idea is errands, not hauling big stuff. Besides with the loss of weight I can connect a trailer if needed. Speaking of dropping weight, including 17 lbs of power brake apparatus, copper wiring and 170lbs of battery boxes and support bracing, *the total weight removed is now about 255 lbs!* 

The new battery box I'm guessing will weigh no more than 45 lbs including the top. The new *4/0 aluminum* pack cables, about 12' each to the engine compartment will only weigh 4.7 lbs. *That gives me a net weight loss estimated at 205 lbs plus 719 battery lbs for a total of 924 lbs as of today.* Old weight 4147, new weight 3223, a 22.3% drop! That should save me about 90-100 watts/mile I'm hoping after allowing for wind losses.

I'm planning on replacing the leaf springs with composite springs for another huge weight loss. On average a 70% weight savings they say. However my springs for the lead batteries are 5 leafs versus the factory 2 so I expect to save a big chunk there.


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## ElectriCar (Jun 15, 2008)

Yea I just read the manual that came with them. Said they are shipped at 60% SOC. Lots of neat stuff in there like start the cooling fan once the batteries reach 40C (104F), go to limp mode at 50C (122F) and shut down the motor at 55C (131F). Also said to charge to 3.6V but never exceed 3.9V. Lots of conflicting data in the manual versus what I've read on this site. I tried to post the PDF manual but it's like 5MB which is too big for this site.

I have a cycle analyst to install, HVC relay already installed, a Zeva plus fuel gauge driver to drive the factory fuel gauge which I'll likely install tomorrow. I'm getting a ventilated battery box built and hope to have it on hand by early next week. Going to install probably 3 120mm PC type ball bearing fans to draw air out if it overheats operated at 12V. Also a heated mat of some sort underneath to keep them warm in winter.


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## ElectriCar (Jun 15, 2008)

Almost finished the Zeva install today. Only two things left to do, mount and connect it to an LED for a "Low Battery" indicator and interface it with my tach. To do that I'm installing a double throw switch, one position is to operate the tach as normal, the other position will display amps on the tach. I thought that would be cool, an analog amp meter!

I removed the connector socket and soldered the wires directly to the board. That makes a better connection but I had to do it anyway or the top wouldn't go on without moving it or using a larger box. 

The toggle switch disconnects the 12V to reset it to full in case the Ah counter reads full too soon or doesn't reach full.

We cut the steel and welded the bottom rack this evening so it shouldn't be long before we can start the install. I may install that piece tomorrow. I'm so ready to drive it!


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## NabilAhmad (Feb 26, 2011)

Just a quick question based in my own ignorance: Will that loop in the power cable inside your ZEVA box effect the hall-effect on the ZEVA? I know the shape is irrelevant, but my concern is the proximity of the other portion of the cable, and its opposite orientation and current flow direction.


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## ElectriCar (Jun 15, 2008)

I doubt it. CT's are used in close proximity to high current wiring all the time. Never heard of interference like that.


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## JRP3 (Mar 7, 2008)

I normally finish my charge around 3.45 or so. No good reason to go higher and unlike lead acid cells lithiums last longer if under charged. I may even lower it a bit more.


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## ElectriCar (Jun 15, 2008)

I was wondering what to charge mine to. Let me know what you decide. I'm about to install mine and start charging, maybe Monday time permitting. This is the base of my single battery pack. The framework is being welded for me as I can't weld aluminum...


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## JRP3 (Mar 7, 2008)

Actually what I'll probably end up doing is just end the charge around 3.45 as now but eliminate the 15 minutes of CV charging. Now I have CV come on around 3.45. By skipping the CV stage I eliminate one failure point, the timer, and keep the cells about 5% lower SOC than I do now. If I think I'll need more range I can turn the timer on.


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## corbin (Apr 6, 2010)

ElectriCar said:


> For those who aren't up on this, I ordered 51 Calb SE200Ah cells in December for my S10. Paid up front with a check direct to Calb to get a discounted price. This upgrade should boost my trip capacity to around 100 miles from the current 30. It also saves 719 lbs, almost half the weight of the lead pack.


Cool! I'm curious how you are estimating your range of 100 miles? You are estimating about 320 watt-hours/mile?

corbin


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## ElectriCar (Jun 15, 2008)

I'm reducing weight for one. After it's complete I will have eliminated close to 20% of the total weight so that should reduce the watts by close to the same amount. Also the batteries will be much more efficient due to a much lower internal resistance. I'm boosting the voltage to about 165 from 144 which will reduce the current draw further. Also I've compared the numbers of others who've switched and I think my calculations are close if their numbers are accurate.

I've been getting around 500Wh/mile or slightly less since moving to the country with the lead. However I don't plan to drive it down near empty, probably keeping it closer to 85-90 miles if I do approach 320wh/mile. 

I hope to be on the road by next weekend though it won't be finished. I have to get the bed cut out and a box fabricated around the opening. I have the battery box top and a frame being welded of aluminum which I hope to pickup Monday.

One thing I'd like to do is replace the leaf springs with composite springs which they claim averages 70% weight savings. However they quoted almost $600 for a set so I may not do it.


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## JRP3 (Mar 7, 2008)

Unless you do a lot of hills and a lot of stop and go then weight is less important than aerodynamics so you may not see the gains you are predicting.


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## JRP3 (Mar 7, 2008)

I'm using a Manzanita, you can set the CV timer from 15 minutes and up in 10 minute increments. The only reason to use the CV stage is to get as much charge into the battery as possible. Since we know lithium lasts longer when under charged it seems quite reasonable to just skip the CV stage if you don't need to get every amp hour in or out of your pack. Shallow cycling is the best way to preserve your cells, so under charge and shallow discharge. If you are getting much above 3.45V you're already at 90% SOC or higher. Why bother if you don't need it? There is a big difference in SOC between 3.4 and 3.6.


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## tomofreno (Mar 3, 2009)

> If you are getting much above 3.45V you're already at 90% SOC or higher.


 3.45 is about 97 to 98% on my 180Ah CALB cells. TS seem to be a bit different.


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## JRP3 (Mar 7, 2008)

tomofreno said:


> 3.45 is about 97 to 98% on my 180Ah CALB cells. TS seem to be a bit different.


Depends on charge rate and temperature. If I stop charging at 3.45 at 25 amps I'll probably be around 90% SOC.


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## JRoque (Mar 9, 2010)

> I ordered 51 Calb SE200Ah cells


200Ah CALBs? I didn't know they had those. Always thought their highest was 180Ah. If you don't mind, can you share the price you paid delivered to you? Fifty one of those 200Ah cells will give you about 32kW, nice!! If you keep your travel speed in check, you're looking at a ~90 mile range. Not bad.

JR


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## ElectriCar (Jun 15, 2008)

JRP3 said:


> Unless you do a lot of hills and a lot of stop and go then weight is less important than aerodynamics so you may not see the gains you are predicting.


I do have a lot of hills but not so much stop and go anymore. However my average speed has been probably about 35-40 on average so aero doesn't impact me so much I would think. With the extended range I'll be hitting the highway speeds more often. 

I've already gotten the weight down a good bit excluding the batteries. I also just purchased some aero side mirrors which are much smaller than factory and they blend into the truck body also which the other ones didn't. They won't make a huge difference but they will help some when I do go faster. 

I don't know if I can hit 320 but some have reported around that mark with their driving habits. I did average 380 once but I was really going easy on it. I think with the new batteries and my weight saving initiative I will be in the ball park. I will of course report when I have the data.


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## ElectriCar (Jun 15, 2008)

JRoque said:


> 200Ah CALBs? I didn't know they had those. Always thought their highest was 180Ah. If you don't mind, can you share the price you paid delivered to you? Fifty one of those 200Ah cells will give you about 32kW, nice!! If you keep your travel speed in check, you're looking at a ~90 mile range. Not bad.
> 
> JR


Yea they have them. They were making some in a 240 and 400 but I was told they were being discontinued in March. I got them for $1.21/ah. Others have gotten them cheaper but I got mine direct from Calb California. Look up Powerscanner, they are letting them go for $1.12 I believe.


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## JRP3 (Mar 7, 2008)

ElectriCar said:


> With the extended range I'll be hitting the highway speeds more often.


That will hurt your wh/mi numbers. Aero's a bitch  You could do a sloped back bed cap to help, eccomodder.com has some neat designs.


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## ElectriCar (Jun 15, 2008)

JRP3 said:


> That will hurt your wh/mi numbers. Aero's a bitch  You could do a sloped back bed cap to help, eccomodder.com has some neat designs.


 Yea I know, unfortunately. May need to do some drafting! That sloped cap seems to only give you about 3-4% but more than likely would cost due to having to haul it around on other than highway driving. I thought about a tonneau cover but it only gives you about 1%, maybe 2 I think.


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## GizmoEV (Nov 28, 2009)

Do you have a wall meter to see your wall-to-wheel energy consumption? I ask because it would be interesting to compare results. When I first got my LiFePO4 pack I was averaging well over 6mi/kWh measured at the wall. This started dropping and is now about 5.3mi/kWh. This change could be due to pack aging, battery temp, or that I now usually have so much extra capacity that I'm not driving as efficiently as I used to.

In any case, this is still better than the 4mi/kWh I used to get with a lead acid pack.


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## JRP3 (Mar 7, 2008)

ElectriCar said:


> Yea I know, unfortunately. May need to do some drafting! That sloped cap seems to only give you about 3-4% but more than likely would cost due to having to haul it around on other than highway driving.


I think you could build a pretty lightweight aero cap. If you make it touch the cab and use a foam gasket you'd only need to make three sides. Coroplast or foam and epoxy with some plexi or lexan for a window, shouldn't weigh much. You could mock one up with cardboard and duct tape and see what sort of gains you actually get before doing the actual build. I'd try to shape it something like the back end of a Prius.


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## ElectriCar (Jun 15, 2008)

Yes I have a calibrated meter at the office and the house. My reports of wh/mile are based on that, not the truck itself. And I've gone as low at 380 from the wall but that was reeeealy taking it easy, particularly up hills.


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## GizmoEV (Nov 28, 2009)

In that case, if my results are any indication, you should see at least a 25% improvement just from the increased efficiency of the batteries.


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## ElectriCar (Jun 15, 2008)

Does that include your weight savings also? I've managed to reduce the weight about 175lbs after installing the new battery box. The batteries will reduce it another 720 lbs. So that's about 19% total weight reduction which would reduce the required power by 19% if not for drag. With drag maybe 15%??? I don't drive it fast at all, even on the highway. So if that's 15% + 25% due to efficiencies I'm looking at a 40% savings which would put me at about 300wh/mile from the wall. I'll take that anyday!


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## GizmoEV (Nov 28, 2009)

I wondered about how much weight reduction made a difference but I really don't think it is as much as is touted. My Gizmo came with 6 Trojan T-875s and I got 3.74 mi/kWh at best. When I went to 8 U2200UTLs, with a weight increase of 125lbs, I got 4.01 mi/kWh. I blogged about it. The weight with the 6V batteries was 993lbs so with the 8V batteries it would have been about 868lbs. With the LiFePO4 cells the weight is now 829lbs. A 17% weight decrease won't translate into a 33% efficiency increase. The increase is more due to the fact that the LiFePO4 batteries do not have a charge shuttle reaction, do not have to be overcharged to equalize them, and do not have a significant pukert's exponent. I think that I also gained minor efficiencies due to raising the nominal voltage from 48V to 64V thus decreasing the current for a given power demand.


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## ElectriCar (Jun 15, 2008)

Are you saying that with your Gizmo in it's current configuration if you removed 200 lbs you believe it would make no noticeable difference?

If you changed batteries and added 125 lbs at the same time you've done two things. A. Changed the energy source and B. Added weight. If the increased efficiency produced a greater effect than the addition of weight they you certainly would have a net increase in mileage per watt. 

I'm not so sure I follow you here so hopefully you'll clarify this for me.


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## GizmoEV (Nov 28, 2009)

ElectriCar said:


> Are you saying that with your Gizmo in it's current configuration if you removed 200 lbs you believe it would make no noticeable difference?


I'm saying that either adding or removing 200lbs would not make a significant difference in energy efficiency. As my Gizmo sits right now, 200lbs is ~25% of total weight (829lbs w/o driver & luggage). This will not translate into a ~25% increase/decrease in energy efficiency. Remember that rolling resistance isn't significantly affected by weight. Added weight will be noticeable by an increase in energy required to reach a particular speed but will not have a noticeable increase in required energy to maintain a particular speed. I have regen so I gain an increase in regen energy when I go to stop or when slowing on a descent. 



> If you changed batteries and added 125 lbs at the same time you've done two things. A. Changed the energy source and B. Added weight. If the increased efficiency produced a greater effect than the addition of weight they you certainly would have a net increase in mileage per watt.


In the first case I went from 6 batteries to 8 batteries. This increased the weight but at the same time increased the plate area of the batteries. This increase in area meant that the Amps/cm^2 in the new batteries was lower than in the old batteries and was more than enough to compensate for the 125lb increase. The ~14% increase in weight gave me a ~7% increase in miles/Wh.

If I had done a test with the lead acid batteries (I'm not going back to lead acid to test this no matter what ) where I added 20% to the weight and compared the miles/Wh to the empty weight value it would not be a 20% reduction. It might be a 5-10% reduction but not 20%. The same tests done with a LiFePO4 pack will see even less of an effect due to the fact that the LiFePO4 batteries are so much more efficient at high currents.

What I'm getting at is that you will see a far bigger gain in efficiency due to the nature of the difference in battery chemistry than you will be getting due to the weight decrease. Now if the *only* thing you do is accelerate and/or climb hills then weight will have a larger effect.

When I get a chance I'll do some runs with my Gizmo loaded and unloaded to note the difference. I don't know if I can add 200lbs but I'll add all I can.


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## tomofreno (Mar 3, 2009)

> Remember that rolling resistance isn't significantly affected by weight.


 It is directly proportional to it.


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## GizmoEV (Nov 28, 2009)

tomofreno said:


> It is directly proportional to it.


That is true but what is the coefficient? It is not very big so the consequence of additional weight isn't very much where rolling resistance is concerned.


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## ElectriCar (Jun 15, 2008)

I can see where weight won't make much difference when you're not accelerating or hill climbing. In my area though I'm frequently climbing hills and accelerating from traffic lights and stop signs. We're at the foothills of the mountains, even the interstate is constantly changing elevation. 

Your testing will be interesting to see. I look forward to the results.


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## GizmoEV (Nov 28, 2009)

ElectriCar said:


> I can see where weight won't make much difference when you're not accelerating or hill climbing. In my area though I'm frequently climbing hills and accelerating from traffic lights and stop signs. We're at the foothills of the mountains, even the interstate is constantly changing elevation.


Remember that you will also coast farther with a loaded vehicle than an unloaded one. If rolling resistance increased directly with weight then your coasting distance wouldn't change.

I didn't think I would have a chance to do a test run yet but I did this morning. I was going to charge up after each run but I didn't have the time and it was windy so I wanted to try to get the same conditions so I just reset my CycleAnalyst before each run and recorded the results. Because of an accidental early turn on the loaded run it was a little longer and different  than the first and had a couple more accelerations. I did normalize the relevant data to make a comparison. I live about 450 feet above the main portion of the run so the beginning of the run I'm mostly coasting down hill with a small amount of regen. When I regen to a stop I get positive regen current down to about 12 mi/hr and then the battery supplies more energy than captured by regen. At about 2 mi/h the battery current is about 30A. I tried to drive with the same rate of acceleration and deceleration but as that is impossible it is a source of more error in the data. I also climbed hills at the same rate both times otherwise the difference between the two tests would have been even smaller. Battery case temperature was slightly higher for the loaded run but I don't know how much that will affect the results. I used the CA for distance measurements because it calculated the net Wh/mi figure. See the attached pic for all the data.

In summary:
Empty Run weight = 967lbs (including driver)
Loaded Run weight = 1141 lbs
~18% increase in weight.

Empty Run net Ah = 17.46
Loaded run net Ah = 19.57
~12% increase in Ah

Empty run Wh/mi = 132.7
Loaded Run Wh/mi = 147.2
~11% increase in Wh/mi

So you can see that an 18% increase did not turn into an 18% increase in energy consumption. This shows what I have been trying to say. While a decrease in weight will help it won't help as much as many think it will, especially with LiFePO4 batteries. Converting back to an equivalent wall efficiency this last run would be 5.4 mi/kWh. With lead acid I got 4.01 mi/kWh with a slightly lighter vehicle. I still achieved a 35% increase in wall efficiency with the LiFePO4 batteries over lead acid.

HTH,


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## ElectriCar (Jun 15, 2008)

Cool. I noticed your speed avg was 27 at one point. So it did change appreciably just not as much as I expected. One more thing, can you do a run without regen? I don't have regen so I can't recoup any energy. 

Picked up the pack frame work I had welded today and also the top. Tomorrow I plan to install the rack, Flex Watt heaters, enclose & insulate the battery box then install the batteries. Hope to get it on the road by weekend but I won't have the bed modified yet.


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## GizmoEV (Nov 28, 2009)

I could do a run without regen but it burns up my brakes quite a bit. I only get about 3000 miles out of a set without regen. But you can still get a good idea of a non-regen run would be like by looking at the Fwd Ah and the Total Wh figures. These do not count backwards when regening or charging. Since it actually takes energy out of the pack for me to regen below ~12mph I believe this "hurt" the loaded run because it took longer to slow to a stop. Even if it was a net zero result, using the Total Wh and Fwd Ah figures will give you a result equal to or lower efficiency for the loaded run. Note that the net Wh/mi figure increased by 10.93% from "Empty" to "Loaded" and yet the normalized Total Wh figure increased by 11.36%.

The lower average speed in the second run was mostly due to my missed turn and due to some slow traffic on one stretch. I had to go 34 instead of 35mph for a short distance and because I had to stop at a stop light the second time through. Both things lowered my average speed but very likely canceled out on energy usage due to the extra acceleration up a hill.


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## JRP3 (Mar 7, 2008)

How does it cost you energy to regen under 12 mph?


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## GizmoEV (Nov 28, 2009)

JRP3 said:


> How does it cost you energy to regen under 12 mph?


I have a SepEx motor. I haven't hooked up the Calibrator (programmer) unit to check but I believe that the field current is 50A under regen at that slow speed (rpm). The armature isn't able to generate enough to compensate for this. That is why I think it costs.

I know it costs energy because I can watch my amp meter and the CA. Both show negative current and the CA counts Ah used at this point. I have seen as high as -35A on the CA but usually it is about -30A just before regen cuts out.

There is one controller setting which appears to adjust the point at which regen is shut off but I'd rather use up a few electrons and not go through brake pads so fast. 3000 miles on a set is ridiculous. Thank God for regen!


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## ElectriCar (Jun 15, 2008)

Well today was a good one! We got the rack installed and insulated with the heaters AND the batteries. We also drilled some ventilation holes in the bottom to align with the grooves on the sides and bottom of the batteries. These will be used to allow fresh air in for cooling in warm weather. In the winter they will be blocked off. 

Hopefully I'll get it on the road in the next day or two for a test though I've still got some things to do before it's finished. One big road block is finding a suitable project box or something to mount the CA in. The dash simply has nowhere to install it. I bought a sloped box to mount on the dash but the face was a little too short. I've looked everywhere I could think of including Fry's Electronics stores, Radio Shack and online.


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## ElectriCar (Jun 15, 2008)

One thing I forgot to mention, I recorded the IR and AH on the cell tops then sorted them in rows according to IR. Here's a photo of the group. Starting from the left they are .25, .26, .27, .28, .29, .30. The one on the far right is a .36 and is located relative to where it should be based on IR numbers of the rest of the group! Must have been the one I asked for later as a spare. 

Initially I thought .36 may be too high but then it occurred to me that as they age their IR will increase so if I lose one sometime, the IR of the spare will likely be closer to the used batteries by that time.


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## GizmoEV (Nov 28, 2009)

ElectriCar said:


> One big road block is finding a suitable project box or something to mount the CA in.


I bought a project box from Radio Shack and then modified the back side to fit the contour of the dash in my Gizmo. I used black RTV to attach it. On the back side of the top I glued some 1/4" ABS for thickness and then drilled and tapped that for the hold-down screws in the corners of the CA display. The box is ABS so I just used ABS glue. I cut a strip of generic cellphone screen protector for display protection. You can see a picture of it in the second photo of my blog: http://2003gizmo.blogspot.com/2011/01/year-with-lifepo4-batteries-what-have-i.html


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## ElectriCar (Jun 15, 2008)

Thanks Gizmo, yea I may have to go that route. I've been looking for a sloped box but it's looking like I'll have to go a different route. I have no clue how to make one out of plastic but that is another option. The wife says I'm too picky

Well after installing the batteries last night we were about finished installing the bus bars today. Actually had them all installed and were torquing the bolts when I decided on a whim to check the heater circuit and see if it was still good to go. I found the resistance had changed.  Further investigation revealed one of the circuit wires was grounded, to my horror as you could imagine!  

Yes that meant we had to dismantle the pack wiring and remove all 50 batteries. And it's not an easy chore to install them. Upon removing the aluminum heat spreader plate under the batteries, an 8 penny nail was found mashed into the heater, grounded to the foil on the insulation... 

Anyway it's all fixed now and for insurance we cut plastic squares from an oil bottle to lay under and over the power connections, where I figured the fault was before finding the nail.

The pack voltage reads just over 165V now at the 60% factory charge.


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## DIYguy (Sep 18, 2008)

ElectriCar said:


> One big road block is finding a suitable project box or something to mount the CA in. The dash simply has nowhere to install it. I bought a sloped box to mount on the dash but the face was a little too short. I've looked everywhere I could think of including Fry's Electronics stores, Radio Shack and online.


Hey man, sorry, been busy so I'm outa touch here. The CA has a box available from source. It is made for bicycles, so, no biggy. I actually got one with my CA. Did u look on the site? 

What heaters did u end up using?


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## ElectriCar (Jun 15, 2008)

DIYguy said:


> Hey man, sorry, been busy so I'm outa touch here. The CA has a box available from source. It is made for bicycles, so, no biggy. I actually got one with my CA. Did u look on the site?
> 
> What heaters did u end up using?


No haven't been to their site to look for it but I might do that. Will be quicker I think. 

I used 6' of the 17" flex watt from Bean Farm. I cut it in half and pretty much covered the bottom of the box. I used the 20 & 35C switches for control and hi temp safety. I wired them in series by tying the two strips adjacent to each other together and will hit the outsides with 240V & 208V at the office. It will put out about 83 watts on 208V and 110W at 240V. Really nothing when spread over 1500 sq inches, only .07W/inch but in an insulated box it should do the trick. Otherwise I'll have to stick a light bulb in there if Obama will let me keep one. 

Oh yea, I'd really insulate the connections with plastic like I did and the cut ends with rubber tape or such. It's a real PIB to repair an Uh-oh under all those batteries! 

I'm making my battery jumper wires with aluminum 4/0 and compression lugs. I love that stuff, it's so LIGHT! Planning to tie it in to the control/charger and fire it up today.  Though it won't have all the instrumentation, it does have the high limit I installed a few weeks ago, the most crucial thing for charging.


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## DIYguy (Sep 18, 2008)

ElectriCar said:


> No haven't been to their site to look for it but I might do that. Will be quicker I think.
> 
> I used 6' of the 17" flex watt from Bean Farm. I cut it in half and pretty much covered the bottom of the box. I used the 20 & 35C switches for control and hi temp safety. I wired them in series by tying the two strips adjacent to each other together and will hit the outsides with 240V & 208V at the office. It will put out about 83 watts on 208V and 110W at 240V. Really nothing when spread over 1500 sq inches, only .07W/inch but in an insulated box it should do the trick. Otherwise I'll have to stick a light bulb in there if Obama will let me keep one.
> 
> ...


Kewl. Did u use a control relay with the temp switches?

I think there is a length limit on the heat tape for series. You can connect them in parallel. I have some specs somewhere.....


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## ElectriCar (Jun 15, 2008)

DIYguy said:


> Kewl. Did u use a control relay with the temp switches?
> 
> I think there is a length limit on the heat tape for series. You can connect them in parallel. I have some specs somewhere.....


 Here's the deal with the way I connected them. I have two pieces of 3 feet each which means the resistance is the same for each piece. In ANY resistive device if the two pieces are nearly the same in resistance, the voltage drop across them will be about the same because the current through them will be identical. You can take two 100W bulbs and series them on a 240V circuit and they will each have 120V on them, same with the heaters. In your case as long as two pieces are the same length it will work.


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## ElectriCar (Jun 15, 2008)

Today for the first time I'm charging the batteries! If only I didn't have a job I would be a lot further along. Then again I'd not have any money to do the project... 

Anyway I have a battery balance volt meter (see post 26 for photos) temporarily connected along with a Cycle Analyst to monitor things the charging process. I have a voltage relay installed to stop the charge at about 175V as my Zivan NG5 charger will take it to 185V or so as programmed. Have to send it off for reprogramming soon.

The batteries as shipped were charged to 60% per Calb or roughly 120ah. So far I've put in 62+ ah. Since starting the charge, I've recorded the balance meter voltage, total ah in, pack voltage and recorded the time. The time between increments of 0.1V is getting shorter but according to my calculation and their data, I should be able to put in about 80Ah before the pack is charged, though I could probably put more in as the cells tested at about 217Ah each per Calb.


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## tomofreno (Mar 3, 2009)

Some relevant info for you. I had a few cells that were down at about 3.39V when my higher cells were at 3.47V - climbing up the exponential part of the curve. I charged one last night at 5A for 10 minutes, so 5/6 Ah. I charged the pack overnight, and this morning near end of charge that cell was at 3.474V when those formerly highest cells were at about 4.44 to 4.45V. 

You have your relay set to shut off power to the charger, but it might be good to start watching them when your highest cells get to around 3.43V. You are probably less than 10 minutes from hitting 3.6V charging at 10A at that point.


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## ElectriCar (Jun 15, 2008)

Thanks Tom. What I did was check each battery, recording the highest voltage for each of 5 rows. After repeatedly checking them once the pack was approaching full, I marked the highest cell on each row. To the worst offender I connected a DMM and watched it. 

I started monitoring that cell once it hit about 3.40V. Here's the data I recorded. Just prior to hitting the knee, 2Ah increased the pack voltage 0.1V. You can see as it moved into the knee, the ah/0.1V was much less, dropping to 0.5Ah per 0.1V.

Cell V, Pack V, Elapsed Minutes Ah into pack
3.463---170.9-------0--------------118
3.479---171.0-------2--------------120
3.495---171.0-------3--------------120
3.535---171.2-------4--------------121
3.640---171.4-------?--------------121 Climbing too quickly to document further.

I then switched off the charger and waited for the pack V to settle to about 168.5 or so and switched it back on to adjust the volt switch lower. The PackV climbed again to 171.3V but the leading cell had went higher than before to 3.7 something. I then quickly turned the voltage setting down shutting the charger off. 

Because these batteries don't drop off much like lead does, the volt switch hysteresis wouldn't allow a restart. I had set it high before for the lead but I'm going to lower it a bit to get this thing to restart so I can fine tune the cutoff voltage.


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## dtbaker (Jan 5, 2008)

the manual fine tuning of the top-balance is bit of a pain, it took me several days of cycling near the top of charge to get things evened out. At the top of the curve, the cell voltage shoot up pretty quickly, and then also settle pretty quickly if you cut the charge.

After pre-install top balance in parallel, I STILL found cells were not really balanced after install, so I took the time to balance in the car. First I had a couple cells that were headed ballistic while the rest of the pack was not done, so I put a 50watt resistor on the highest ones for about 15 minutes just to pull them down in line with the pack. Then, the best repeatable process I found was:
- allow charge to take pack up to 'finish and settle', but leave it plugged in... about 5 minutes after max voltage, then pack settles down,otherwise you are shooting at moving target.
- record all cell voltages, and unplug
- for cells more than .01v over the theoretical mean, apply 50w resistor... you'll get a feel for how long it takes to know the cell down for each .01v over 'average'
- drive car a minute or two to take pack voltage down enough to reset charger.
- repeat.... charge, measure, unplug, knock down the 'over' cells.


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## ElectriCar (Jun 15, 2008)

I was planning on bottom balancing but I have to discharge, bottom balance then see what happens. Unfortunately I had one cell spike quite a bit before the second worst cell would have hit 3.6V.How much capacity am I leaving on the table if I don't top balance? Not sure but I doubt it's more than 5-600W. 

Two ev'ers have stated they stopped their charge at 3.48 or 3.45 V/cell. I never reached that point before the highest one was hitting 3.6V. I found that between 3.6-3.8V is only a matter of a minute or two. 

My plan was to charge to 172.5V or 3.45V/cell. I only made it to 171.4V when that cell hit 3.72V. To get from 3.6 to 3.72V was a matter of a minute or less at about a 20A charging rate. The remaining 4 of the top 5 cells were only at about 3.45-3.55V. The rest of the pack I think was at about 3.38-3.40? 

Things happen so fast it's hard to keep up with everything, thus picking out the worst 5 offenders to watch and watching the worst of those 5 with a meter connected constantly. After going over the numbers in my head, it looks like I'm going to have to stop the charge at 3.40V or so to ensure the one doesn't get too high. But before I can decide on a final charge voltage I need to bottom balance then charge it again.


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## dtbaker (Jan 5, 2008)

you can't have it both ways.... if you bottom balance you have to have a reliable way to kill the charge when the first cell goes ballistic. Hence my personal decision to stick with top balance and let the charger do its job, and I'll do my job by not over-discharging.


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## ElectriCar (Jun 15, 2008)

You have a valid point. I just don't know about the bottom end yet. I gave that some thought but I have to evaluate the bottom situation as well then I can decide. It did cross my mind that if I bottom balance and still have one top out very early I can set the voltage relay to stop a little earlier. But what happens if the same one changes over time and tops out even earlier? It's a goner then. It's that scenario that bothers me.


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## tomofreno (Mar 3, 2009)

> I was planning on bottom balancing but I have to discharge, bottom balance then see what happens. Unfortunately I had one cell spike quite a bit before the second worst cell would have hit 3.6V.How much capacity am I leaving on the table if I don't top balance? Not sure but I doubt it's more than 5-600W.
> Two ev'ers have stated they stopped their charge at 3.48 or 3.45 V/cell. I never reached that point before the highest one was hitting 3.6V. I found that between 3.6-3.8V is only a matter of a minute or two.
> My plan was to charge to 172.5V or 3.45V/cell. I only made it to 171.4V when that cell hit 3.72V. To get from 3.6 to 3.72V was a matter of a minute or less at about a 20A charging rate. The remaining 4 of the top 5 cells were only at about 3.45-3.55V. The rest of the pack I think was at about 3.38-3.40?


 I don't see why you say you may loose some capacity if you bottom balance. Your pack capacity will be the same whether you top or bottom balance. It is equal to the capacity of your lowest capacity cell. If bottom balanced, you stop charging before that cell hits 3.45V or whatever you choose below HVC (3.6V for CALB), and stop discharging when that cell and most others are at about 30% SOC or 20% SOC. If top balanced, you stop charging when that cell, and most others, are at 3.45V or whatever, and stop discharging when that cell is at 30% SOC or 20% SOC. Either way you have the same pack capacity.

It is a good idea to watch all the high voltage cells, because sometimes the one that first hits the knee, later gets left behind by another. Their resistance can vary significantly from each other on that exponential part of the curve. I wouldn't worry at all about differences in voltage on that part of the curve for that reason. Plus you are talking about tiny Ah differences between cells that are at different voltages at or above the knee.

Cell voltage changes pretty quick above the knee doesn’t it! That’s why I and others have said just stay away from the exponential parts of the charge and discharge curves, and life is easy. There is no reason to go there since the amount of energy gained is so small, maybe a couple miles in range. 

Once you get your relay tweaked in so it cuts power before your high cell hits 3.45V or so, the pack final SOC should be fairly repeatable if you always charge at the same current. Can't you have your charger set to stop there also? I would set it to shut off just before your relay would kick off. You may see some variation in final SOC with cell temperature. If so, your CA will show it. But you shouldn’t go over 3.45 on that cell because of your relay, unless cell voltages drift or the relay fails. I didn’t see any significant drift over the about 1 ¼ years I watched before top balancing, except for when I overcharged two cells to about 3.95V. One of them then became my high voltage cell. Prior to that, I had the same high voltage cell for about a year. I wouldn't be surprised if they change as they age though.

The imbalance at the bottom that results from top balancing is no problem for me since I never go below 30% SOC on my lowest capacity cell.


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## dtbaker (Jan 5, 2008)

exactly... the problem is that if just one cell is above the others, its going to take off way before the total pack voltage climbs much. Unless you have cell level BMS that can shunt or shut down charger, I have concluded (for myself anyway) that top-balance is my best chance at letting the charger do its job as simply as possible and manage the charge curve as the pack voltage come up and starts up the curve. If the cells don't hit the curve at about the same time, the high ones could be VERY high.


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## ElectriCar (Jun 15, 2008)

This morning I top balanced to 3.44V, meticulously working to get them all there. Then I turned on the charger and here's the results. 

Yesterday to get from 169.0V to 171.0V took 53ah and 2 hours.
Today to do the same it took 1.06ah and 2 minutes! 

Now I'm very perplexed. Maybe this has something to do with a new pack and creating tunnels in the electrolyte? Tell me what you think. I'm totally blown away.


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## dtbaker (Jan 5, 2008)

unless you discharged by driving around a little... all you had to add this morning was basically the 'surface charge'. you probably ought to leave the headlights on for a while or take a 5 minute drive, then charge again.


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## tomofreno (Mar 3, 2009)

> exactly... the problem is that if just one cell is above the others, its going to take off way before the total pack voltage climbs much.


 This isn't an issue for a bottom balanced pack with cells matched as well as Electriccar's. Wasn't an issue for me, and mine were not as well matched as his due to replacement of 4 cells.



> Yesterday to get from 169.0V to 171.0V took 53ah and 2 hours.
> Today to do the same it took 1.06ah and 2 minutes!


 Sounds like Dan said, there was no discharge of cells so they were already full. I think most of the charge you add during the exponential part of the curve just diffuses away when you turn off the charger, as there are few sites left for intercalation - I would guess that is why the resistance increases and voltage rises exponentially.


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## ElectriCar (Jun 15, 2008)

The voltage I selected, 3.44V to balance to was chosen because that was the lowest cell voltage after sitting overnight. Was that a good voltage? I noticed now after recharging they aren't balanced again but are close, probably within a tenth but I don't think any went above about 3.45V.


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## dtbaker (Jan 5, 2008)

I would say that for balancing purposes, the further up the curve you go, the closer you will be able to get in balancing, which is why I tried to catch all mine right after the CA-CV trigger voltage, after just a couple minutes when they had stopped 'relaxing' and changing too fast, but were still up the curve. My experience was that as they are just coming off the flat part of the curve everything looks great and together, but as you climb the differences show up fast.


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## JRP3 (Mar 7, 2008)

You also need to use reduced current during balancing. Are you still charging at 20 amps?


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## ElectriCar (Jun 15, 2008)

During balancing? I balanced them then flipped on the charger. The charger starts cutting back from 30A somewhere around 170V. On the first charge it had cut back to around 20A when it finally cut off at 171.6V. At around 172.5V on the old lead pack, the current program in the charger, it finishes up at 10A or so. 

Once I get the pack to stabilize so I can get a good stopping voltage, I'll send the charger off for the new program. I think since I balanced it I will be able to charge a couple of volts more if need be. I already passed the voltage from yesterday with no ill effects.


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## JRP3 (Mar 7, 2008)

I guess I didn't know how you were balancing, I thought you were charging the pack and bleeding off the high cells while charging. If the charger is already set to stop at 172.5 that would be fine at 3.45 per cell, no good reason to go any higher since they'll last longer by not being fully charged and you have a margin of safety.


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## ElectriCar (Jun 15, 2008)

I shut the charger down when the high cell went over 3.6V twice and just went home to mull it over. This morning I started balancing the pack. For cells within .001V or 2, I used these 6V lamps used in emergency lights I had laying around the shop, a very light load. For cells reading much higher I used this battery tester to quickly bring them down. You can quickly bleed up to 4 at a time with this to get them close, then switch to the lamps. This only took about 2 hours or so of rechecking and bleeding off before I got all 50 cells to stabilize at 3.344V, not 3.44 I think I stated earlier. The next charge went very smoothly!


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## ElectriCar (Jun 15, 2008)

ElectriCar said:


> That's how they arrived but I'll figure it out once they're all connected and I can charge them for the first time.
> 
> Finished the brake conversion today. Works like a champ so far. The pedal rests in the right place keeping the brake light off, something I was concerned may not happen.
> 
> ...


Finally the conversion is completed. After swapping master cylinders about 3 times, bench bleeding, reinstalling and trying to bleed the brakes again for the 37th time I found the push rod was too long by 3/16" or so, even using the factory master cylinder and push rod assy. 

Evidently the pedal location was a little too close to the firewall compared to the '85 the hardware came off of. This prevented the piston on the MC from retracting all the way so once the bench bleeding fluid was pushed out, the rear cylinder became empty. Finally the combination valve popped and the brake light came on. Couldn't get it to reset until the real problem was found. This left me with front brakes only until I found the problem. I solved it by placing some 3/8 washers between the firewall and the MC.

Anyway a power brake to manual conversion is a huge hit on convenience! Seriously it takes a lot more pedal pressure to stop even with 4w disc. BUT, it's a hell of a lot better than that damn pump coming on every other stop brrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr. God that was irritating! I can live with the pedal pressure. My right thigh muscle may become grossly larger than the left though by the time I wear out those Calb batteries...


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## ElectriCar (Jun 15, 2008)

Oh yea I forgot, drove it around today about 4 miles after finally bleeding the brakes. Still have some finishing up to do but it's drivable now.


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## JRP3 (Mar 7, 2008)

Sounds as if you didn't locate and isolate the pump properly. Mine in the back corner of the trunk sitting on foam can't be heard when driving and can barely be heard when stopped. If you ran yours to the back corner of the vehicle under the bed soft mounted in a box or something it probably would have been fine.


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## ElectriCar (Jun 15, 2008)

JRP3, silence is golden. I still can't get over how quiet this thing is now. I keep expecting the thing to come on. Silence... 

Today I drove it a little and it's amazing the difference in pep this new voltage has. As I hit the pedal to go it just wants to take off! I have to get used to that and take off a little easier. 

I'm doing some wh/mile notes also as the speed sensor isn't connected to the CA yet. It's looking real good so far. I think I only put about 30Ah back into the pack to go 26 miles. That don't sound right and it's probably not. Tomorrow I'll hopefully have more and better data. I never reset the CA before when I did the initial charge so the counting was all screwed up. I reset it tonight after it finished. I LOVE THAT THING!


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## ElectriCar (Jun 15, 2008)

Well I've been driving for two days without charging to run the pack down and see how far I could go except I briefly charged for about 45 minutes yesterday and added 17.9Ah back to the pack. I went 110.2 miles on 205Ah and could have went further. How much I don't know but I was starting to see the volts drop a little faster than normal but not alarmingly fast or anything. When I got out it said I had used 187.1Ah but I had to add 17.9 to that for the total. 

The conditions were mostly driving 40-55 in my commute which has several traffic lights and quite a few hills and moderate driving, no hard starts or such. Ran the heat for maybe 5 minutes. 

Total watts used from pack, includes brief charge at the office: 32,880
Total Ah: 205
Watts/Mile from pack: 298.36

One final note. Calb says when the open circuit voltage, or voltage with no load on it is 3.1V, it's over 85% discharged. In my pack that would be 155V. When I stopped it was 157.4V or 3.148V so assuming at least 15% remaining, apparently I still had over 15, maybe 17 or 18 miles available before destruction.


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## JRP3 (Mar 7, 2008)

Nice efficiency. Though I don't recommend it I've taken my CALB's down to 1.77V under load and 2.45 at rest with no apparent problems.


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## ElectriCar (Jun 15, 2008)

Wow so that's 122.5 on my pack. Dude that's really taking it down! How far did you drive after noticing the voltage was starting drop off until you got to that point? Just curious but I thought once it started falling off a bit that it wouldn't take long before it fell off the cliff! And what's the size of your pack?


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## JRP3 (Mar 7, 2008)

I have 36 100ah cells. I noticed voltage dropping about 4 miles from home and the controller started cutting back power. It was actually dropping sooner than that but I wasn't paying attention until the controller started cutting back power. The last two miles I was doing about 20 miles an hour max on the side of the road with my flashers going but I made it. The only reason I ended up in that situation was because it was soon after I had gotten it running, I didn't have the charging worked out and didn't realize I had under charged the pack, and I didn't have an amp hour gauge installed and wasn't paying close enough attention to voltage. Basically operator error all around


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## ElectriCar (Jun 15, 2008)

Today I completed another very useful electronic gadget installation. In fact while setting it up another use came to mind. 

I installed another ABB voltage relay to automate the precharge and idiot proof it! I just replaced two of the EV200 contactors because one had welded shut and the other stopped closing when energized. I suspect it was partly my fault and partly Tyco's, see the Kilovac EV200 thread here at post 41. 

So here's my setup. A previously installed precharge relay (PR) energized while the ignition was on. At the same time one of my two HV contactors, C1 came on. I passed pack voltage via PR through 3 paralleled 750ohm 25W resistors which applied current limited power to charge all the caps. I used that many due to the additional 10,000uf cap bank I installed. The resistors were energized the entire time I drove wasting power, little though it was. The other contactor C2 was operated via throttle pot switch, expediting it's demise I'm sure! 

The ABB voltage monitor relay I labeled PVR, with two sets of NO/NC contacts monitors the precharge voltage and is set to energize at 156V, roughly 90% of full pack voltage which is what Kilovac recommends for longevity. Once energized, an NC contact disables PR to save a few watts while a NO contact now energizes C2 to apply full voltage to the controller. The throttle pot now has no control of C2 but C1 is always closed under no load thereby prolonging it's contacts life.

The second useful function mentioned earlier is the ability to kill controller power when the pack voltage falls too low. There are two adjustments I can adjust to do this. One is the hysteris adjustment, variable from 0-30% of the setpoint. I set it at 3% so it would drop out at about 150V or 3.0V/cell. Calb says with no load, 3.1V is >85% discharged which is about as low as I want to go anyway. 

The other adjustment is a time delay. Once the setpoint is reached, there's now a 2 second delay before it activates. Likewise I think once the voltage drops below 150V I'll have 2 seconds for the voltage to go back up or it will open the C2 effectively killing power to the controller. If that's not enough delay I can adjust it for more delay.

Since I have no bms, this should work well as a LV cutoff. The delay feature can compensate for brief voltage sags when approaching empty.


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## JRP3 (Mar 7, 2008)

3V seems too high for a LVC under load, I know it would be for my cells but since they are smaller I pull higher C rates and have more voltage sag. Still it would be bad to have your power shut off as you're going up a steep hill. I don't like the idea of a full power shutdown, you might be in a situation where you'd rather keep moving to save your ass instead of stopping to save a cell  I think a warning buzzer or something might be better. Or if possible set your controller to start cutting back power.


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## NabilAhmad (Feb 26, 2011)

Love it on so many levels. I've been wanting to make the precharge circuit voltage based - I'm loving the idea of buying an off the shelf module. $150 seems reasonable for all it gives. I look forward to updates on it's performance.

The low voltage cutoff is something you will find all kinds of opinions about, but it should be based in real experience per vehicle. Obviously during acceleration and moderate loads, the sensed voltage will drop. And will drop significantly below the manufacturer's "at rest" voltage/discharge curve. Where it gets fishy is not any particular arbitrary voltage mark, but how quickly the batteries will get to a trustable "at rest" point. Can you get that while coasting, cruising, or only after at a stop light for several seconds?

Also, in the case of a low V cutoff event, if the voltage sag recoups after a second or two, what do you expect the behavior to be? Just a sudden reinstatement of power? Or do you need to perform a deliberate routine? 

And, what is the additional current draw on a PR circuit once the main contactor is closed? Shouldn't it be zero? If it is anything, is it more or less than the a relay's energized current draw? I ask because I've been wondering this myself and would love some real-world experience to inform me.

Thanks a lot!



ElectriCar said:


> The ABB voltage monitor relay I labeled PVR, with two sets of NO/NC contacts monitors the precharge voltage and is set to energize at 156V, roughly 90% of full pack voltage which is what Kilovac recommends for longevity. Once energized, an NC contact disables PR to save a few watts while a NO contact now energizes C2 to apply full voltage to the controller. The throttle pot now has no control of C2 but C1 is always closed under no load thereby prolonging it's contacts life.
> 
> The second useful function mentioned earlier is the ability to kill controller power when the pack voltage falls too low. There are two adjustments I can adjust to do this. One is the hysteris adjustment, variable from 0-30% of the setpoint. I set it at 3% so it would drop out at about 150V or 3.0V/cell. Calb says with no load, 3.1V is >85% discharged which is about as low as I want to go anyway.
> 
> ...


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## ElectriCar (Jun 15, 2008)

During that 110 mile test it only got down to 155 near the end, never near 150. What I'm hoping is that the delay will allow time for the sag. Otherwise I can tweak the hysteresis setting to a little lower level, just don't want to get too low. Once it drops out the pre-charge kicks back in and the cycle repeats. 

I probably should set it for 9% which will allow it to dip to around 140 which is 2.8V and back off the timer. 140 should be fine but I've not been down in that region and hope I never need to.


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## ElectriCar (Jun 15, 2008)

NabilAhmad said:


> Also, in the case of a low V cutoff event, if the voltage sag recoups after a second or two, what do you expect the behavior to be? Just a sudden reinstatement of power? Or do you need to perform a deliberate routine?
> 
> Thanks a lot!


No idea, I've never been that low but Calb batteries have a very low IR which probably explains why at near empty my batteries only dropped to 3.1V at the lowest.


NabilAhmad said:


> And, what is the additional current draw on a PR circuit once the main contactor is closed? Shouldn't it be zero? If it is anything, is it more or less than the a relay's energized current draw? I ask because I've been wondering this myself and would love some real-world experience to inform me.
> 
> Thanks a lot!


With my current setup of 3 resistors the current draw when precharging is .68A. I'm going to add a 4th resistor this morning which will take it to about 1A but speed up charge time. Now it takes about 25 seconds at full charge to get it to 155V. I'm thinking when the voltage drops after driving a while it will take longer, just don't know how long. It is drawing no current after the setpoint is reached BTW.


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## GizmoEV (Nov 28, 2009)

A couple of things to consider. I know I have TS cells and you have CALB but when the cells are cold you can get the voltage to sag to below 2.93V with a 1-1.5CA current draw even when they are at 99%SOC. By cold I mean down below 10°C. My BMS boards send a LVC at 2.93V.

Second, why bother taking the precharge resistors out of the circuit when they are in parallel with the main conductor? Only a minuscule amount of current will flow through them. If you leave them hooked up and you have a LV event you won't have to wait for a precharge when the voltage bounces back.


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## ElectriCar (Jun 15, 2008)

GizmoEV said:


> A couple of things to consider. I know I have TS cells and you have CALB but when the cells are cold you can get the voltage to sag to below 2.93V with a 1-1.5CA current draw even when they are at 99%SOC. By cold I mean down below 10°C. My BMS boards send a LVC at 2.93V.


I have an insulated & heated battery box which should keep the temps up. They will be heated but only when plugged up. I may mod it to power the heaters via pack voltage if I see a problem with keeping them warm.



GizmoEV said:


> Second, why bother taking the precharge resistors out of the circuit when they are in parallel with the main conductor? Only a minuscule amount of current will flow through them. If you leave them hooked up and you have a LV event you won't have to wait for a precharge when the voltage bounces back.


I haven't thought about that. It was only a couple of wires but it never entered my mind like that! OTOH, it should extend the precharge relay life as it won't be subject to additional heating by the coil being energized on those hot summer days like now.


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## ElectriCar (Jun 15, 2008)

One more piece of the puzzle completed. I have stolen an idea from Gizmo to control my CA display power so it isn't powered except when ignition is on or charging, the only time necessary to count the Ah activity.

We both have Zivan chargers which have a contact which activates when the charger is powered. I use the NO contact there to close and power a separate relay which 1. disables the controller control power and 2. energizes the CA positive lead.

A second set of contacts are "Charge Complete" activated. I used the NC contact on this one to interrupt power to the CA at that time.

I would post schematic drawings of this and other work but have no idea how to other than drawing by hand, photographing & scanning them for upload. ???


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## JRP3 (Mar 7, 2008)

The CA doesn't reset when powered off?


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## dtbaker (Jan 5, 2008)

JRP3 said:


> The CA doesn't reset when powered off?


I have mine wired to 'always on' power... it floats around a little, but is not pretty close to zero amps at rest. There is a manual reset I hit once in a while after a full charge.

I figure it is pretty close, and there IS tiny draw from dc-dc all the time it may be seeing.


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## ElectriCar (Jun 15, 2008)

Nothing is lost when it powers down other than the screen I last viewed. It returns to the first screen which I guess is default. I'd like to change it but not an issue right now. I'll look at that once I get it actually mounted. Gizmo has his wired to operate this way and he also has a relay to make the display dim when he switches the lights on which I don't think I'll do.

I've finally got all the preliminary wiring to the CA and my split pack voltage meter completed. The voltage divider circuit board made from Radio Shack components and the relays to control and power the CA are in a 6x6x4 PVC water tight box under the hood.


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## dtbaker (Jan 5, 2008)

ElectriCar said:


> Nothing is lost when it powers down other than the screen I last viewed.


I wanted mine always on because there are MANY days that I grab partial charges between errands and I wanted to track the partial ah in when the ignition is 'off'. I have one of the earlier CA units, and it doesn't seem to handle 120v very well despite replacing a couple resistors per instructions. The on/off seemed hard on the unit, so I wired to leave it on all the time except for the very first reset to get to the calibration menues.


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## GizmoEV (Nov 28, 2009)

dtbaker said:


> I wanted mine always on because there are MANY days that I grab partial charges between errands and I wanted to track the partial ah in when the ignition is 'off'. I have one of the earlier CA units, and it doesn't seem to handle 120v very well despite replacing a couple resistors per instructions. The on/off seemed hard on the unit, so I wired to leave it on all the time except for the very first reset to get to the calibration menues.


At times I wish I could see the Ah values without having to turn the key on but I can see the Ah while charging so it hasn't been too much of an issue for me.

The reason I went to having it controlled by the key and charger was that it would count too many Ah out of the pack when everything was turned off. It didn't seem to matter how many times I zeroed the shunt calibration it was just too far off from reality for my tastes. When the Ah figure is significantly off after a full recharge I recalibrate again. Right now it reads slightly faster on discharge than on charge which if there were an error this is the way I'd want it to be off.

I'm really glad I installed the second button. It allows me to scroll through the displays either directions but more importantly I don't have to power cycle it to get to the setup menu.


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## GizmoEV (Nov 28, 2009)

ElectriCar said:


> Gizmo has his wired to operate this way and he also has a relay to make the display dim when he switches the lights on which I don't think I'll do.


If the display is too bright at night you could just install a pot or do what I did and install some 1/8W resistors until I reached the brightness I wanted. Without them the display was killing my night vision.

Did you get the option of hooking up a computer to record data? I'd be interested in what your charge current looks like. Mine fluctuates up and down all the time. I think this is due to the PWM of the charger and the sample rate of the CA. I don't know if this actually averages out or not. I've wondered what would happen if I installed a small capacitor across the shunt if it would smooth things out or mess up the current reading.


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## ElectriCar (Jun 15, 2008)

No option for data collection but the amps does fluctuate a bit during the tapering off of the amperge as it nears full charge. In fact it fluctuates nearly an amp I'm guessing. 

Last night was the first charge after driving since the reprogramming, the amperage trickled down to only about .6 even though the voltage was still .8V off. It took forever to get the last ah in there, probably a half hour if I had to guess!


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## ElectriCar (Jun 15, 2008)

dtbaker said:


> I wanted mine always on because there are MANY days that I grab partial charges between errands and I wanted to track the partial ah in when the ignition is 'off'. I have one of the earlier CA units, and it doesn't seem to handle 120v very well despite replacing a couple resistors per instructions. The on/off seemed hard on the unit, so I wired to leave it on all the time except for the very first reset to get to the calibration menues.


Gizmo and I use a "power on" contact on the charger that activates whenever the charger has power to energize a relay and power the CA. The Zivan also has an "end of charge" relay that activates at the end which we use to disconnect power to the CA via a relay.


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## dtbaker (Jan 5, 2008)

ElectriCar said:


> Gizmo and I use a "power on" contact on the charger that activates whenever the charger has power to energize a relay and power the CA. The Zivan also has an "end of charge" relay that activates at the end which we use to disconnect power to the CA via a relay.


hhmmm, the elcon has an output wire, but it puts out PACK voltage when not plugged in, and 0 volts when plugged in. I use it as an interlock signal to prevent driving when plugged in. I kinda like having the CA display on while charging so I can see the amps going in and see at a glance if it is done or how much I got on a partial charge... it seems to be pretty close and only require occasional zeroing right after full charge finishes.


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## GizmoEV (Nov 28, 2009)

ElectriCar said:


> No option for data collection but the amps does fluctuate a bit during the tapering off of the amperge as it nears full charge. In fact it fluctuates nearly an amp I'm guessing.


It looks like mine is showing just under a 2A range from top to bottom. See the attached graph of the first 5 minutes of charging. On a full charge it varied much more than this just before the current started tapering back.



> Last night was the first charge after driving since the reprogramming, the amperage trickled down to only about .6 even though the voltage was still .8V off. It took forever to get the last ah in there, probably a half hour if I had to guess!


That sounds reasonable. I would expect that the farther down the "knee" of the voltage curve you charge that the longer the last part of charge will take.

There was a discussion on the EVDL about the validity of my conclusions about how much energy is above 3.4V. Since I did those tests I've heard from one individual who said they worked for a LiFePO4 manufacturer and that they found that they could get 100%SOC charging to 3.4V if the ending current was low enough. This agrees with the "float" voltage listed on the CALB spec sheet. The long and the short is that I'm going to try to get a hold of some 40Ah cells and starting at 50%SOC, charge them according to the TS specified charge profile of charge to 4.00V and hold until the current drops to 0.015CA and stop. My PS can at most put out just over 6A so I'll need the smaller cell to test. I'll then lower the ending voltage and charge until all the energy taken out is replaced and note the ending current. I'll report what I find. It was proposed that there is a possibility that with my 3.485vpc ending voltage and <200mA ending charge current that I could still be over charging my cells. We'll see.

Do you know what the final current was when your charger shut off? Did the fans stop before the end of charging? They do on mine.


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## ElectriCar (Jun 15, 2008)

The fans did stop several minutes before the end and the lowest I saw was about .6A, thoug it may have dropped at the very end, not sure. I went and took a shower as it finished and when I returned it had stopped.


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## ElectriCar (Jun 15, 2008)

Gizmo I am adding the 2nd button. Already installed two switches, pack monitor meter and an "Precharge Complete" led to the CA enclosure. 

Yesterday I completed the wiring for all that from the control box under the hood to the cabin, connected the led, CA and volt meter. Sitting in the shop all was well. Upon starting to drive, the volt meter flipped out! The voltage shot up, display dimmed then it died. 

I found the problem today and repaired it and ordered a new meter, two actually as this was meter #2 I've torched! Cable fault (caused my moi...) The CA didn't care at least! 

With my Fluke meter though the pack monitor meter circuit works great, just need to protect those cheap meters which evidently have no high voltage protection built in. The replacement meter however will have a zener and limiting resistor added across the monitored input for protection.

*FYI, the precharge voltage monitor works great! * I've tried to drive off a couple of times before I added the charge complete LED and it wouldn't let me. Technology is just amazing isn't it?


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## ElectriCar (Jun 15, 2008)

*Lithium battery long range has exposed problems!*

These batteries have exposed two issues. I'm in an area full of hills & seldom on flat ground for more than a few seconds. On the interstate or highways you're constantly going up and down hills around here. The motor and Curtis 1231C controller overheated on a trip Friday night. 

I drove on the interstate for a trip of 33 miles with a 30 minute stop then returned. It was only 70F outside and dark! I was trying to maintain about 60mph with current occasionally peaking to 225A, most of the time in the 50-150A range. After reaching the interstate and driving about 5 miles or so it started cutting back due to overheating and at one point I slowed to 45 up a hill with a HUGE semi on my butt! Coasting down hills allowed it to cool enough to get a good start on the next hill.

I have TWO fans on this thing with a 3/8 aluminum plate on it. The plate is oversized about 2" all the way around. When I had lead, this plate fixed this on all but the hottest days. With these batteries and longer trips possible I'm going to add a finned heatsink. 

This trip also exposed the fact that I must operate the motor at higher RPM or add a blower. When I got home and plugged in I smelled motor paint. The motor surface measured about 150F, in the brush area closer to 170. I drove in 4th gear with RPM around 2800 on average. I never thought at 60-65mph in 70F air it would get that hot. 

Geez it's always something on these things! I guess that's reality when you're DIY'ing.


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## JRP3 (Mar 7, 2008)

Try 3rd gear. I'd say you're driving about 1000 RPM too low for efficiency and cooling, though your current draw doesn't sound all that high, but the higher motor speed will pull more air through it. Is your controller mounted above the motor? If so it might be getting too much motor heat as well as it's own internal heat.


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## ElectriCar (Jun 15, 2008)

I just feel better keeping the rpm lower on the trans input shaft. I've seen the bearing there and there's not much to it. It's a little needle bearing and just doesn't look like it could take much abuse.


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## dtbaker (Jan 5, 2008)

*Re: Lithium battery long range has exposed problems!*

I have a hood scoop forcing air thru a finned heatsink (http://www.heatsinkusa.com/) for the controller... no troubles there, but since I have done a couple longer drives at highway speed with lithium, I DO notice some heat build up that never happens on my short around-town trips. I have a couple remote thermometers in my battery boxes, which are not vented or cooled.... and on the 20+minute highway runs I do see the temp start to climb in the battery box too.

For people doing longer trips at highway speed I would agree that well-planned cooling is probably required for motor, controller, and even battery boxes.


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## EVfun (Mar 14, 2010)

ElectriCar said:


> I just feel better keeping the rpm lower on the trans input shaft. I've seen the bearing there and there's not much to it. It's a little needle bearing and just doesn't look like it could take much abuse.


The transmission input shaft bearing shouldn't be doing anything when you are driving. It only turns when the clutch is released, all other times the motor shaft and input shaft are turning together, leaving them stationary relative to each other. On many vehicles this is not even a bearing, just a bronze bushing.

The Curtis will be destroyed by repeated overheating. The motor current was likely a lot higher than your battery current at the low rpm, well past its continuous rating. You really need to rev up to cool down the motor and controller. The Curtis 1231 is only rated for 250 amps continuous *motor* current. Motor current is always higher than the battery current unless the throttle is floored.


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## JRP3 (Mar 7, 2008)

I can't imagine any transmission not able to run at 3800 rpms.


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## DIYguy (Sep 18, 2008)

Well, I think u got it right. . . Ur batteries exposed the next weakest link. While I'm not against thick aluminum plates for mounting controllers, I think that this is like a "storage tank" for heat energy more than it is for disipation. It will soak up heat well until it is "full" as it doesn't get rid of it too well. The fins are better. Water is better yet. I put a blower on my motor right from the start. The other thing u can do is to pick a lower gear to keep the rpm up higher on warmer days. Sounds like u have some work to do b4 it gets real hot. 

I took mine out foir a spin last week. It drove just fine but when I stepped on it, I kinda expected more. So, I hooked up the laptop and sure enough the current was backed off from last year. I cranked it up to 1000 amps and went back out for a rip. 2nd gear spun the tires pretty good, but the pavement was a little wet. But I was up to 80mph in no time. I stopped, put it in 3rd gear and floored it. After it got moving, wow! Did it ever pull. Then. . Bang! Blew up the Soliton. Second time. Maybe I should change my signature to "Solitons blown up by my motor - 2". . 
They are really good about though and will fix for free even tho the original purchase date is more than a year ago. That said, it was rebuilt less than a year ago due to that film capacitor supplier problem. This time its expected to be the same current sensing issue that caused Jack R's to put out less than 1000 amps. Mine was in the other direction. Lol. At 170 motor volts (after sag) and 1000 plus amps, the truck really boogies.


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## valerun (Nov 12, 2010)

DIYguy said:


> Maybe I should change my signature to "Solitons blown up by my motor - 2". . At 170 motor volts (after sag) and 1000 plus amps, the truck really boogies.


what is your motor? ;-) Also, what is the pack nominal voltage? 

I have yet to see 1000A at high RPM on my Soliton1 setup. Running 250V Kostov 11" and 256V nominal pack of 100AH CALBs.

V


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## JRP3 (Mar 7, 2008)

DIYguy said:


> This time its expected to be the same current sensing issue that caused Jack R's to put out less than 1000 amps. Mine was in the other direction. Lol. At 170 motor volts (after sag) and 1000 plus amps, the truck really boogies.


So the controller was putting out more than 1000 amps, because of incorrect current sensing calibration? How are you cooling your Soliton?


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## DIYguy (Sep 18, 2008)

valerun said:


> what is your motor? ;-) Also, what is the pack nominal voltage?
> 
> I have yet to see 1000A at high RPM on my Soliton1 setup. Running 250V Kostov 11" and 256V nominal pack of 100AH CALBs.
> 
> V


9" GE motor.

66 Calb 180 ah... so, about 211 volts nominal I guess.


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## DIYguy (Sep 18, 2008)

JRP3 said:


> So the controller was putting out more than 1000 amps, because of incorrect current sensing calibration? How are you cooling your Soliton?


Yes, this is what was assumed. I have a breaker with adjustable trip limits. Last year I popped it a few times when it was set at 1150 I think it was. Also, the CA said I was putting out more than 1000 when I tromped it. I think this is why I set it back a bit last year. Kindof forgot about that. 

They came up with a new current sensor and calibration procedure to fix this problem. I think the sensor could be influenced by cables routed close to it on the outside of the case.. in either an additive or subtractive mode. Jack's was the latter I expect. 

As for cooling, I am just using the air cooling. I bought a small water pump for it more than a year ago, but I found that it never got hot enough to need anything more than air. That said, I am planning to install it... after the rest of the upgrades are complete. Usually, my high amp events are not that long in duration.


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## ElectriCar (Jun 15, 2008)

EVfun said:


> The transmission input shaft bearing shouldn't be doing anything when you are driving. It only turns when the clutch is released, all other times the motor shaft and input shaft are turning together, leaving them stationary relative to each other. On many vehicles this is not even a bearing, just a bronze bushing.
> 
> The Curtis will be destroyed by repeated overheating. The motor current was likely a lot higher than your battery current at the low rpm, well past its continuous rating. You really need to rev up to cool down the motor and controller. The Curtis 1231 is only rated for 250 amps continuous *motor* current. Motor current is always higher than the battery current unless the throttle is floored.


No I'm not talking about the pilot bearing inside the bell housing. This is the actual bearing inside the transmission that turns with the input shaft. 

And I didn't know it was only rated at 250A continous duty. But again, it was at night in cool air and less than 250A peak! I guess that thick plate just acts like a sponge and soaks heat in until it saturates and then the controller overheats since it only happens on longer hauls at higher speeds.


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## EVfun (Mar 14, 2010)

ElectriCar said:


> And I didn't know it was only rated at 250A continous duty. But again, it was at night in cool air and less than 250A peak! I guess that thick plate just acts like a sponge and soaks heat in until it saturates and then the controller overheats since it only happens on longer hauls at higher speeds.


The rating is for motor amps, not battery amps. If you foot is not floored motor amps are higher than battery amps. It is also an optimistic rating with great cooling. The smaller 1221 is only rated for 150 continuous motor amps. 

I don't think any of the bearings inside the transaxle and supplied with oil whipped up by the gears are a concern. I think running the motor at 2800 rpm at freeway speeds is a much bigger concern. Motor amps are going to be quite a bit higher than battery amps at that speed.


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## ElectriCar (Jun 15, 2008)

*Re: Lithium battery long range has exposed problems!*



dtbaker said:


> I have a hood scoop forcing air thru a finned heatsink (http://www.heatsinkusa.com/) for the controller... no troubles there, but since I have done a couple longer drives at highway speed with lithium, I DO notice some heat build up that never happens on my short around-town trips. I have a couple remote thermometers in my battery boxes, which are not vented or cooled.... and on the 20+minute highway runs I do see the temp start to climb in the battery box too.
> 
> For people doing longer trips at highway speed I would agree that well-planned cooling is probably required for motor, controller, and even battery boxes.


Those are priced right, unfortunately I already ordered the one on the top right in the link. Seems to be pretty popular for the Curtis 1231C.


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## ElectriCar (Jun 15, 2008)

DIYguy said:


> Well, I think u got it right. . . Ur batteries exposed the next weakest link. While I'm not against thick aluminum plates for mounting controllers, I think that this is like a "storage tank" for heat energy more than it is for disipation. It will soak up heat well until it is "full" as it doesn't get rid of it too well. The fins are better. Water is better yet. I put a blower on my motor right from the start. The other thing u can do is to pick a lower gear to keep the rpm up higher on warmer days. Sounds like u have some work to do b4 it gets real hot.
> 
> I took mine out foir a spin last week. It drove just fine but when I stepped on it, I kinda expected more. So, I hooked up the laptop and sure enough the current was backed off from last year. I cranked it up to 1000 amps and went back out for a rip. 2nd gear spun the tires pretty good, but the pavement was a little wet. But I was up to 80mph in no time. I stopped, put it in 3rd gear and floored it. After it got moving, wow! Did it ever pull. Then. . Bang! Blew up the Soliton. Second time. Maybe I should change my signature to "Solitons blown up by my motor - 2". .
> They are really good about though and will fix for free even tho the original purchase date is more than a year ago. That said, it was rebuilt less than a year ago due to that film capacitor supplier problem. This time its expected to be the same current sensing issue that caused Jack R's to put out less than 1000 amps. Mine was in the other direction. Lol. At 170 motor volts (after sag) and 1000 plus amps, the truck really boogies.


 Wow you've just exposed the Soliton, it's not bullet proof!!! Well any idea why they are blowing? Arcing in the motor possibly? Oh yea, glad to see you're driving it again. I've just about finished with my upgrades, only needed to finish mounting the CA enclosure until this weekend. BTW, what's your motor and how did you do the forced air, kit or scratch made?


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## tomofreno (Mar 3, 2009)

The 3/8" aluminum plate a bit larger than the controller is not nearly enough. Like diy said, you mainly are just using its heat capacity (which isn't that much) to store heat without much dissipation so it heats up fairly fast. You need lots of surface area and lots of air flow for forced convection. Water cooling is only as good as it's liquid/air heat exchanger. It's main advantage is the later can have large surface area and be mounted in an area of good air flow, and with a high capacity fan. A temp of 150 F for the motor isn't that bad though, only about 66C. It should be rated to something like 120C or more. My motor gets to that temperature regularly each summer, but not in 70F weather. 

I think evfun hit the nail on the head with the motor current. Sounds to me like you are lugging it. I'd run it at 3500 to 4000 rpm. I usually cruise with my AC50 between 4500 and 5800 rpm. It stays noticeably cooler compared to running in a higher gear. Max rpm is 8k - I'd run it a bit higher but worry about the transmission. 

I think the controller is more of a concern. Mine gets over 60C on hot summer days even with a heat sink with 2" deep fins with air flow and a 250 cfm fan blowing on it if running on the highway or up extended hills pulling around 150 or more amps continuous for about 20 minutes or more. Climbing 4590 ft in 70F ambient pulling about 140 to 230A for about 25 minutes the motor got to 53C, controller 48C. Much more difficult to keep things cool when it is 37C outside.


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## JRP3 (Mar 7, 2008)

ElectriCar said:


> Well any idea why they are blowing?


As stated it was passing higher than rated current because of a calibration/current sensing problem. I think the first issue was they had a batch of bad caps.


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## ElectriCar (Jun 15, 2008)

Tom there are two fans blowing on that plate but being it's a plate with not so much surface area to cool. Hope to have a finned sink on by the weekend.


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## Tesseract (Sep 27, 2008)

ElectriCar said:


> Wow you've just exposed the Soliton, it's not bullet proof!!! Well any idea why they are blowing? Arcing in the motor possibly?...


"Exposed" the Soliton, huh? I didn't realize there was a perception that we had tried to cover anything up, especially since the film capacitor issue was discussed here and the current sensor issue was a central theme in two of Jack Rickard's videos...

In neither case was "arcing in the motor" a problem. Soliton1's routinely survive short circuits across the motor terminals (there's even a thread about it here) as well as motors arcing so badly they fail in a fireball of plasma.

The problem in the first instance was a bad film capacitor - a problem the capacitor manufacturer admitted to and corrected. I'm pretty sure we were the first major customer for that capacitor but if not, they have said we definitely push it harder than anyone else. So, we were unwitting beta testers for them.

The second problem, however, was partially my fault in that I used a bare magnetic field sensor to measure the current through the motor output bus plate. Unfortunately, that sensor picked up magnetic fields besides those from the bus plate, but I didn't realize how much error this could lead to until Gary told me the circuit breaker on his battery pack - set for 1150A - kept tripping (see quote below). Doubly unfortunately, our IGBT supplier then told us we wouldn't be getting any more product for the next 6 months. 

At any rate, that problem was solved by redesigning the bus plates to accommodate a conventional current transducer. 

Now imagine how we might have responded to Gary's issues if we were deluded into thinking there was no way one of our controllers could ever blow up? Also, that nothing untoward happened as a result of our controller blowing up shows that it fails gracefully and safely - I'd say that's a net positive, actually.




DIYguy said:


> ... I have a breaker with adjustable trip limits. Last year I popped it a few times when it was set at 1150 I think it was. Also, the CA said I was putting out more than 1000 when I tromped it. I think this is why I set it back a bit last year. Kindof forgot about that.
> 
> They came up with a new current sensor and calibration procedure to fix this problem. I think the sensor could be influenced by cables routed close to it on the outside of the case.. in either an additive or subtractive mode. Jack's was the latter I expect.


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## ElectriCar (Jun 15, 2008)

Tes, nobody is calling you guys out. It was all just fun about one of you guys having that in your sig about 0 Solitons failing. That was however the first I'd heard about one failing. All I've heard is good things about the Soliton.


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## JRP3 (Mar 7, 2008)

Tesseract said:


> "Exposed" the Soliton, huh?


I see your boxers showing


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## EVfun (Mar 14, 2010)

I wrote earlier:


> The Curtis 1231 is only rated for 250 amps continuous *motor* current. Motor current is always higher than the battery current unless the throttle is floored.


Having just pulled out my manual I thought I should correct that statement. The 1231C controller doesn't have a continuous rating. It has a 1 hour rating of just 225 amps.


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## ElectriCar (Jun 15, 2008)

And you know the only thing in my head is "500 Amps" though I know that's only instantaneous. I know a guy who can make it 1000A but I forget the cost. He's an authorized Curtis repairman.


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## ElectriCar (Jun 15, 2008)

Today my cooling fans kicked on for the first time but not from battery heat, just from the box being in the sun. It's 91 outside and they're on a 104F thermostat. Nice to see it works!


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## DIYguy (Sep 18, 2008)

If I recall correctly, your battery box is exposed on the top poking through the truck bed. ?? Just wondering what colour it is on the top? If its dark, you may want to go with something more reflective like white or silver?

What about the controller cooling? Its not too hard to make your own watercooled Alum base. Just drilling, cross drilling and plugging can work just fine. You drill two long/deep holes, then cross drill near the end to connect them and plug. Then do other end. I've also seen two sizes of drills used with a plug set deeper inside to block/route water, then one at outer hole. Even if you had to loop the passages together externally, its not the end of the world.


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## ElectriCar (Jun 15, 2008)

It's currently an unpainted aluminum top and gets very warm in the sun but the entire box is lined with R4 foam with radiant barrier on the side against the top. The batteries were only reading 95F when I checked them so not sure how long the fans had been running.

Re the heat sink, I ordered a pretty large finned heat sink and will have the fans blowing into the fins from underneath. I think surely that will do the trick! The motor now is ran at higher rpm when it's in the 90's like today and on long runs.


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## ElectriCar (Jun 15, 2008)

Well recently I went with the 1000 amp upgrade. I must say having 1000A available is absolutely mind blowing at what this truck will do now! Seriously I'm afraid to floor it as it I think is capable of applying more torque to the transmission that it is designed to take. It has a T5 5 speed, non world class for those of you in the know about these things.

The upgrade included more efficient parts thus eliminating a lot of heat build up created from the increased pack voltage. I had to do something as I couldn't drive on the interstate at 65-70 as it would throttle back in a short distance due to overheating, even with two fans running in 70F air! 

As of yet I've not installed the fans back on it but did install a finned heat sink. I've gotten about 1000 miles or so and it's yet to cut back. The highest controller temp I read with an IR handheld meter was around 112F. 

Seriously, if you want to drive at interstate speeds and still have the ability to pass someone while peeling the paint off their doors, you should try a 1000A controller, it's like a supercharged V8 under the hood!


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## JRP3 (Mar 7, 2008)

Can you give some details on the upgrade, what was involved, parts, cost, etc. You can't just throw out "1000 amp upgrade" and not give us any details


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## JRoque (Mar 9, 2010)

JRP3 said:


> Can you give some details on the upgrade, what was involved, parts, cost, etc. You can't just throw out "1000 amp upgrade" and not give us any details


Or a video run!

JR


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## ElectriCar (Jun 15, 2008)

I sent it off to Dave Mosher at Custom Electronics. He's on this site and is a Curtis Authorized repair tech. He upgraded the diodes which made it run much cooler and upgraded the 10 mosfets to 130A units. 

What I'm not pleased with is there isn't any "accel rate" anymore that I can tell, meaning if I nail it, it's going instantly wide open like a dang RC car with no ramping up, just full on. So if you punch it, tires are gonna spin! 

I blew the controller with less than 100 miles on it when passing someone who had been driving slow on the interstate, and I didn't floor it either, never have. I'm afraid if I do it could damage the transmission or coupling.

He did warranty it but I think it failed because there is no current limit like I had before. He says there's some sort of voltage based current limit which I don't have a clue what he's talking about, all I know is if I even bump the accelerator the tires will chirp! Knowing this I've learned to make sure I press it easily. It's seriously bad azz!


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## JRoque (Mar 9, 2010)

Hi. So you mean there's no ramp between two accel positions? Does it feel "stepped" instead of smoothly going from a lower position to a higher one? So if you slowly depress the accelerator then it works because the changes are small, correct?

If so, I would first try with some of the guys here that know their way around the Curtis programmer. If the mod made it so there's no way around the stepped speed, then you can add a small circuit between your pedal and controller to ramp it up again.

JR


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## ElectriCar (Jun 15, 2008)

JRoque said:


> Hi. So you mean there's no ramp between two accel positions? Does it feel "stepped" instead of smoothly going from a lower position to a higher one? So if you slowly depress the accelerator then it works because the changes are small, correct?
> 
> If so, I would first try with some of the guys here that know their way around the Curtis programmer. If the mod made it so there's no way around the stepped speed, then you can add a small circuit between your pedal and controller to ramp it up again.
> 
> JR


No, there's no gradual increase in power applied to the motor, it's on if you push the pedal! As far as making an external ramp device, I already thought about that but it only uses a variable resistance to get an input, not a varying voltage. It may be possible that an input voltage can be applied to it and work, if so I can use the pot with an extrenal voltage to make one. Maybe someone will comment about that.


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## JRP3 (Mar 7, 2008)

Is this controller compatible with the Curtis programmer? If so you can rent one from Travis to change the throttle ramp. 
Maybe the upgrade was just gutting the controller and installing a big contactor


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## ElectriCar (Jun 15, 2008)

Don't recall any ability to program this unit. It's the 1231C.


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## EVfun (Mar 14, 2010)

It sounds like there is an issue with the current limit. Usually the Curtis is noted for having an excessively slow throttle ramp rate that pretty much prohibits a decent burnout. 

If you want to moderate the throttle you can put a capacitor in parallel with the throttle pot. This was done a few times to tame the older B model Curtis controllers in reverse. It is a variable voltage set by the resistance across the pot.


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## ElectriCar (Jun 15, 2008)

EVfun said:


> It sounds like there is an issue with the current limit. Usually the Curtis is noted for having an excessively slow throttle ramp rate that pretty much prohibits a decent burnout.
> 
> If you want to moderate the throttle you can put a capacitor in parallel with the throttle pot. This was done a few times to tame the older B model Curtis controllers in reverse. It is a variable voltage set by the resistance across the pot.


 If that's so I wonder if I could use an external supply and generate a voltage through the pot and apply it to the correct terminal, which I also don't know which one it would be.


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## ElectriCar (Jun 15, 2008)

The Curtis 1000A mod was most awesome however it lasted only about 3000 miles, has blown up 3 times costing me two tow bills and three blown 400A fuses. Enough of that!

Upgrading to a Soliton1. It came Friday and unfortunately it was damaged. The Ethernet port was smashed and pushed into the controller. Looked like UPS ran it through a trash compactor! Based on the note in the box about not setting the controller down on that side, they should probably switch from plastic to a metal housing or recess the terminals in a raised metal box projecting from the side of the controller for protection. 

I was however able to make a template before sending it back. THIS THING IS HUGE and heavy. The mounting board I have has to be reworked as it's nearly 20" length wouldn't fit with my existing layout. I also had to shorten the mounting frame to keep the hood from closing on it as it's about 6 inches high. The thing looks pretty much bullet proof! Can't wait to get it going!

I know some of you have switched to Soliton as well, the more I learn of it the more I see the value in it. There truly is no comparison to the Curtis I had but the S wasn't available when I bought it. 

So did you build a new mounting board to mount yours? My first one was 3/4 plywood. I'd like to use something thinner like a plastic of some sort. What did you use or what do think would make a good base for it?


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## JRP3 (Mar 7, 2008)

Aluminum plate.


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## DIYguy (Sep 18, 2008)

ElectriCar said:


> The Curtis 1000A mod was most awesome however it lasted only about 3000 miles, has blown up 3 times costing me two tow bills and three blown 400A fuses. Enough of that!
> 
> Upgrading to a Soliton1. It came Friday and unfortunately it was damaged. The Ethernet port was smashed and pushed into the controller. Looked like UPS ran it through a trash compactor! Based on the note in the box about not setting the controller down on that side, they should probably switch from plastic to a metal housing or recess the terminals in a raised metal box projecting from the side of the controller for protection.
> 
> ...


Congrats!
Unlike some controllers, the Soliton1 comes with a substantial Aluminum base with integrated water cooling. So, u don't really have to mount it on aluminum . . although, as JRP says, it's not a bad idea. I just used a piece of Teflon because I had it and thought electrical isolation isn't a bad thing. I would not use wood. . it's just not the right material for automotive. 
I would definitely hook up the water cooling circuit though and run it through a small rad. Use the optional output to drive an ice cube relay. This feature works great. Although I didn't use the water cooling when I ran lead, I found that the added available power did cause the controller to limit power on warmer days.
Our builds "were" always close in many ways. . . now u change ur controller to what I've been using. . . and I'm changing mine again...lol


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## ElectriCar (Jun 15, 2008)

Whew, Teflon and carbon fiber are outrageous! I think a 3/16 sheet of cf would be awesome but it's about half a G. Just can't make myself spend that much on it! JRP I thought the same thing but I'd be concerned about vaporizing a wrench or something using aluminum! 

Now to get the AC back working before it gets hot...


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## ElectriCar (Jun 15, 2008)

Haven't done an update in a while but lots of stuff to report. Got the 1 going in mid August and have since put about 4400 miles on it. I'm doing around 1300 miles/month. *I've saved $1133 in just over 3 months*, well on my way to the estimated $2500-3500/year when I decided to build this thing!  *At this clip, by next August I'll have saved about $4500! And this is after deducting for property taxes and insurances costs. 
*
A bit of disturbing news now. Today I hit the 10,000 mile mark on the pack and *I've noticed a significant drop off in the capacity of the Calb pack.* It's much worse than I expected IF my metering is correct. I'll need to do it again to verify the CA info, I'll explain.

Originally the mileage limit tested to around 110-120 miles. I did a LOT of driving one day last week and when I made it home I was at about 190Ah. Voltage was still OK so I didn't sweat, after all these batteries were tested to about 210+ Ah when new. Being near empty I decided to go ahead and see just how much I could use before serious voltage drop so I drove down the street to stay within walking distance. I ran it down to 198 of the 200Ah capacity per the CA and the controller shut down at 150V or 3.0 VPC as I had set it to do. I walked the mile to the house, took the PC and lowered the threshold to 135V and drove it back. 

198Ah wasn't the correct Ah though as the CA had drifted and was showing 5Ah once recharged. That said, *it looks like the pack was depleted at only 193Ah*. I don't reset the CA every time I recharge so the error accumulates until I reset it. On this trip, I documented and charted the last 40 Ah or so versus the voltage after no throttle for 5 seconds at each reading on a trip back home but the numbers on the chart aren't in even increments. 

So in short, at 10,000 miles it appears my Calb pack purchased in January 2011 has lost about 9% capacity. I need to test it again after resetting the CA to verify this. If this is the case, it doesn't look good if this capacity decrease is linear. By the time I reach the 100K mark, I'll have no pack but I'll still have saved an estimated $22000 or so which will completely cover the cost of the conversion and several thousand dollars to boot. In reality I'm not convinced it will last that long. At the rate I'm going now though it won't take long to find out. 

I'll continue to document my capacity and mileage over time and repost it if my old head remembers to do so!


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## GizmoEV (Nov 28, 2009)

Make sure the CA actually reads 0A when no current is flowing. Mine wanders around quite a bit, apparently depending on temperature.

How many Ah has the pack delivered? That would give an idea of the number of equivalent full cycles.

What are your typical sustained current values and also peak values?

I've heard that the decline in capacity isn't linear but more exponential decay in nature. I'm hoping that is true. Please keep us posted.


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## jeremyjs (Sep 22, 2010)

GizmoEV said:


> Make sure the CA actually reads 0A when no current is flowing. Mine wanders around quite a bit, apparently depending on temperature.
> 
> How many Ah has the pack delivered? That would give an idea of the number of equivalent full cycles.
> 
> ...


I dunno. All the cycle life charts I've seen are very linear in nature, other than the first 50 cycles or so where the capacity increases a few percent, then declines a few percent. I've never done it myself though. 

Let us know what you come up with. How far do you normally drive before you recharge? 9% seems like an awful lot for such a short time.


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## ElectriCar (Jun 15, 2008)

GizmoEV said:


> Make sure the CA actually reads 0A when no current is flowing. Mine wanders around quite a bit, apparently depending on temperature.
> 
> How many Ah has the pack delivered? That would give an idea of the number of equivalent full cycles.
> 
> ...


Hi guy. I've noticed it varies with temp. Re how many it has delivered, not sure about that. This thing came in with some data already in it and I didn't reset it. Not sure I could have or not. Maybe it can be calculated somehow. 

I have the Kw put back in the pack from the wall since new and know it is about 13% more than the watt hours from the CA so that would get me a close approximation. I'll try and do that tomorrow. I'll also post the spreadsheet from that trip and another shorter recent trip up to I think about 75Ah.

Peak current has hit 1000, likely close to 1500 for a split second when I had that bootleg Curtis in there. Now I have the Soliton set to 1000 but seldom hit that high anymore. Acceleration is usually 350-400 for a few seconds then it tapers off to maybe 75-150 depending on local roads or interstate.


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## ElectriCar (Jun 15, 2008)

jeremyjs said:


> I dunno. All the cycle life charts I've seen are very linear in nature, other than the first 50 cycles or so where the capacity increases a few percent, then declines a few percent. I've never done it myself though.
> 
> Let us know what you come up with. How far do you normally drive before you recharge? 9% seems like an awful lot for such a short time.


Drive to work is about 13 miles for my normal route and I recharge nearly every time right away. Most of the time I recharge at less than 50% depletion but using it like I do, it's not uncommon to drive it down to 60-75%.


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## GizmoEV (Nov 28, 2009)

ElectriCar said:


> Hi guy. I've noticed it varies with temp. Re how many it has delivered, not sure about that. This thing came in with some data already in it and I didn't reset it. Not sure I could have or not. Maybe it can be calculated somehow.
> 
> I have the Kw put back in the pack from the wall since new and know it is about 13% more than the watt hours from the CA so that would get me a close approximation. I'll try and do that tomorrow. I'll also post the spreadsheet from that trip and another shorter recent trip up to I think about 75Ah.


When I got my CA I had been driving with my pack for a while. I had kept track of the kWh out of the wall so I just calculated an average Ah into the pack for a given kWh out of the wall and then figured how many net Ah that would equate to. Since I have regen I know my figure is a little low but within 4% as I've measured since. I then entered this value into the CA. If you have two buttons installed then it is really easy to program in. If you only have one installed then you have to power cycle the CA to get it into programming mode.

Right now my pack has ~165 full cycle equivalents on it since January 2010. For my little rig this is almost 15kmiles. I haven't notices a decrease in capacity but then I rarely discharge it to the bottom.


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## ElectriCar (Jun 15, 2008)

The CA says it has 158 cycles, 31,000 miles and 41,800Ah which is obviously wrong as I use about 2Ah/Mile or so and have only 10000 on the pack, some of which was on another CA which I blew.

I need to do a Zero amps adjustment which I periodically do when I notice an accumulation of error in the Ah total. Not sure what else I can do to ensure accuracy with it. 

Also the actual amps this morning on the interstate varied from <100A to 400A up hills at 70mph or so which was a little more than I posted earlier but I know lots of people exceed 2C a lot more frequently than I do due to an undersized pack of 70 & 100Ah cells. That's one reason I went with 50 200Ah cells, to minimize amp draw. I would have went with a higher voltage but was limited by the motor and DC/DC.

I plan to post the data I recorded re VPC versus Ah used and see what you guys think this afternoon. I may start another thread re lithium battery Ah deterioration after more data if indeed it appears I have lost nearly 10% capacity in 10K miles.


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## jeremyjs (Sep 22, 2010)

60-70% DOD should see a cycle life quite a bit higher than the rated cycle life is at 80% DOD. Something like 50% higher for each 10% less total capacity used from most of the charts I've seen. Again I haven't tested this myself, but more than a few sources claim similar numbers.


Oh what are your temps like? You definitely can loose 9% is cold weather.


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## DIYguy (Sep 18, 2008)

Make sure u check the other obvious stuff too like connections and balance.


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## ElectriCar (Jun 15, 2008)

jeremyjs said:


> 60-70% DOD should see a cycle life quite a bit higher than the rated cycle life is at 80% DOD. Something like 50% higher for each 10% less total capacity used from most of the charts I've seen. Again I haven't tested this myself, but more than a few sources claim similar numbers.
> 
> 
> Oh what are your temps like? You definitely can loose 9% is cold weather.


It is in an R4 insulated box with a heater. 

*Are you saying that cool batteries will empty sooner than warmer ones?* I don't think they are cool at all but I can check if that's what you're saying. I'd guess they are around 70F or so as it's not been cold here at all except at night and then it's in the garage. Also I have added a tonneau cover a while back so the pack box isn't so exposed to cold blowing air like it was.


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## ElectriCar (Jun 15, 2008)

DIYguy said:


> Make sure u check the other obvious stuff too like connections and balance.


Yea I think I'm good with that. In fact I have some data to post for you guys to look at which I think is telling if we can analyze it properly. I've located 3 or 4 batteries to keep an eye on, those with the lowest voltage near empty. I recorded voltages near the bottom and then post recharge for each battery. Some varied just a little and some quite a bit. I don't think it can be determined though which ones have more capacity or lower resistance etc but it would be nice.


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## jeremyjs (Sep 22, 2010)

ElectriCar said:


> It is in an R4 insulated box with a heater.
> 
> *Are you saying that cool batteries will empty sooner than warmer ones?* I don't think they are cool at all but I can check if that's what you're saying. I'd guess they are around 70F or so as it's not been cold here at all except at night and then it's in the garage. Also I have added a tonneau cover a while back so the pack box isn't so exposed to cold blowing air like it was.



If they're insulated and heated I don't think that would be it. Especially since it's not cold where you are. The batteries generate more heat at cooler temps. They all have to deliver the same power is series, but the voltage will drop more, for a given amp draw, in colder batteries. They generate less apparent power, but the difference is equal to the energy being released inside of the battery as heat. From what I understand it's from the ions generating more heat; because it's more difficult for them to intercalate at cold temps. Some call it internal resistance; because that's what it looks like from the outside.

I'm just throwing out ideas. It just seems odd that you'd loose that much capacity over such a relatively small number of cycles.


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## ElectriCar (Jun 15, 2008)

OK here's the data. There are two sheets with different data. Tell me what you think. Hope the attachment works...


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## Jesse67 (May 12, 2009)

I wouldn't worry about your apparent capacity decrease until you reset your cycle analyst at the end of a full charge and do another test. Also remember that it's current reading and thus Ah count are only as accurate as the shunt calibration. Do you have another current meter you can compare it to? You can also reset your zero amps value when you know there is no current going through the shunt, ie, everything is off except the CA.

Good luck!


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## DIYguy (Sep 18, 2008)

The best way to know the true capacity is to pull a cell, and use a battery discharger, like the PL8 or CBA to record it's capacity . . . ideally comparing it to an earlier test done the same way. The cycle analyst is a nice tool, but not really that good at capacity testing.


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## ElectriCar (Jun 15, 2008)

Jesse67 said:


> I wouldn't worry about your apparent capacity decrease until you reset your cycle analyst at the end of a full charge and do another test. Also remember that it's current reading and thus Ah count are only as accurate as the shunt calibration. Do you have another current meter you can compare it to? You can also reset your zero amps value when you know there is no current going through the shunt, ie, everything is off except the CA.
> 
> Good luck!


That's what I just did today. Here's a PDF. The date though should be today. I'll post more info tomorrow, discharge and charge voltages for each cell.


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## Ziggythewiz (May 16, 2010)

So still at ~95% of spec. Most of the curves I've seen indicate a non-linear decay where you lose the first 10% far faster than the next 10% and a very gradual slope before it's down to 70%.

I've long thought CALBs ship well over spec so that they can degrade a good chunk while remaining above the 80% spec for a long time.

DIY data is much more valuable than anything the manufacturer puts out though, so we'll be looking for updates with interest.

How high do you typically charge/discharge them?


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## Jesse67 (May 12, 2009)

That's an even better answer. (from DIY guy) 

Is that just manual data from your cycle analyst or did you use the data logging feature?


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## ElectriCar (Jun 15, 2008)

Ziggy I hope you're right re the 1st one being the larger drop in capacity. And yea I'm still able to drive it to 200Ah but it's pushing it, as you can see the voltage is dropping fast.

Jesse I just manually logged the voltage at the Ah shown and made the graph. This was mainly just a benchmark for later on as I've never done it before.


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## ElectriCar (Jun 15, 2008)

DIYguy said:


> The best way to know the true capacity is to pull a cell, and use a battery discharger, like the PL8 or CBA to record it's capacity . . . ideally comparing it to an earlier test done the same way. The cycle analyst is a nice tool, but not really that good at capacity testing.


Yea but this way will suffice. Don't have those things anyway. It'll be clearer when I post the voltage data at 198Ah and again when recharged for each cell.

BTW, you've been on the road a while, how's your pack? Any data to share? I really think we could use a separate "experience" thread but who keeps data like I do? Not too many I suspect. It's a bit of a PIB but it's handy for others to know.


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## Ziggythewiz (May 16, 2010)

ElectriCar said:


> Ziggy I hope you're right re the 1st one being the larger drop in capacity. And yea I'm still able to drive it to 200Ah but it's pushing it, as you can see the voltage is dropping fast.


I'm not finding the curves I've seen before, but here's one that shows what I've heard is the norm for LiFePO4 cell wear. The real tell will be to see what your cells are like after 20k miles.


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## ElectriCar (Jun 15, 2008)

Is this what you are looking for? I had them saved on my computer.


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## drgrieve (Apr 14, 2011)

That PDF was interesting, looks like you hit the knee at 165AH. Do you take the pack often past this point?

I assume since you're quite calm bringing your pack down you have it bottom balanced. What is your general charging routine - do you charge to 100% or do you undercharge slightly?

Thanks for sharing!


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## ElectriCar (Jun 15, 2008)

drgrieve said:


> That PDF was interesting, looks like you hit the knee at 165AH. Do you take the pack often past this point?
> 
> I assume since you're quite calm bringing your pack down you have it bottom balanced. What is your general charging routine - do you charge to 100% or do you undercharge slightly?
> 
> Thanks for sharing!


Last week I went down to 198 but kept a keen eye on the pack voltage. No it's top balanced but it won't stay balanced. Call it drift or whatever but there are certain cells that end up climbing higher than the others over time. They were actually marked shortly after the initial install. I've only balanced it about 2 times in the last 6-8000 miles or so I'm thinking. 

If there's time I recharge until finished. You can see the VPC I charge to on the chart. It varies slightly with temperature but is safely under any danger of spiking cells. 

Here's the discharge voltage for each cell at 198Ah from last time and the again after recharging along with the voltage change from empty to full.


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## JRP3 (Mar 7, 2008)

I wonder if top balanced cells are more prone to drifting apart than bottom balanced? I think most of us with bottom balanced packs don't see much drift.


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## tomofreno (Mar 3, 2009)

JRP3 said:


> I wonder if top balanced cells are more prone to drifting apart than bottom balanced? I think most of us with bottom balanced packs don't see much drift.


 How many miles do you have on your pack, and when is the last time you checked?


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## JRP3 (Mar 7, 2008)

I've got around 10K, and last check was a few months ago, so I'm not a great data point, other than effects of calender life. Jack Rickard claims little drift on his packs.


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## ElectriCar (Jun 15, 2008)

Is there anything generally speaking that can be determined, ie resistance or Ah capacity of particular cells based on that last file with the empty/full voltage and the change of each cell? I'm not very sure of what's going on to explain the differences there.


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## Ziggythewiz (May 16, 2010)

ElectriCar said:


> Last week I went down to 198 but kept a keen eye on the pack voltage. No it's top balanced but it won't stay balanced.


Do you have any monitoring to tell you if any of the cells are going much lower than the others when you're that low?


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## EVfun (Mar 14, 2010)

JRP3 said:


> I've got around 10K, and last check was a few months ago, so I'm not a great data point, other than effects of calender life. Jack Rickard claims little drift on his packs.


How does one determine drift on a bottom balanced pack? Short of a very deep cycle that takes the pack below the bottom knee I don't see how drift would be determined. With a top balanced pack I can look for it every charge (I only check once or twice a month.) I am seeing a little upward drift in some added cells, but the 32 cells with 2 years in the buggy stay together, and the 6 added cells stay with each other.


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## GizmoEV (Nov 28, 2009)

ElectriCar said:


> Is this what you are looking for? I had them saved on my computer.


Too bad that graph doesn't go on out past 500 cycles. It is too short to see if the capacity drop starts to level out. Given the wild fluctuations at different points it could be that your pack is in one of its low times and will bounce back.


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## JRP3 (Mar 7, 2008)

EVfun said:


> How does one determine drift on a bottom balanced pack? Short of a very deep cycle that takes the pack below the bottom knee I don't see how drift would be determined.


That's one way, the other is to check during charge and see if the finish voltage changes between cells. Just because a pack isn't top balanced doesn't mean the cells don't have specific voltages when charging.


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## ElectriCar (Jun 15, 2008)

GizmoEV said:


> Too bad that graph doesn't go on out past 500 cycles. It is too short to see if the capacity drop starts to level out. Given the wild fluctuations at different points it could be that your pack is in one of its low times and will bounce back.


Hope that's the case. I'll continue to monitor them. Maybe at 15000 I can do it again. This month I'll end up with about 1500 miles or so. Past 1300 already and will likely do over 100 today. 

My customer is across from a city park and I think it has a free charging station. I finished my J1772 adapter box a while back and it works fine on GE stations but on the Eaton units it faults out, I think due to current exceeding 30A. The GE Wattstations must have a higher current limit threshold or something as they won't fault out after starting up.

Oh, if you don't have it and do a lot of driving, I've found there are a lot of free stations around these days, especially in parking garages where there's often a dedicated EV parking space or two and government buildings. I downloaded an app called "EV Charger Locator" on my smart phone to help me get free electrons!


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## tomofreno (Mar 3, 2009)

EVfun said:


> How does one determine drift on a bottom balanced pack? Short of a very deep cycle that takes the pack below the bottom knee I don't see how drift would be determined. With a top balanced pack I can look for it every charge (I only check once or twice a month.) I am seeing a little upward drift in some added cells, but the 32 cells with 2 years in the buggy stay together, and the 6 added cells stay with each other.


 I think that is the difference. Most, if not all cells in a top balanced pack are driven up into the exponential part of the curve each charge where change in voltage with Ah added is much greater, magnifying small differences in SoC. The cells in my pack show the same voltage to within a few mV during most of the charge, until around 3.44V or so where some start to increase a bit faster in voltage than others. I recently did some work on my pack heaters and had the bms boards disconnected from some of the cells for several days. Even with around 2Ah difference in SoC of these cells from the rest, all cell voltages were about the same until around 3.44V where these cells started quickly pulling ahead in voltage as they entered the exponential part of the curve while the others had not. If the pack is bottom balanced you likely won't see any difference in cell voltage if all cells are below 3.44V when charging is ended. I think you would have to monitor cell voltages while driving with cells at 25% or less SoC to see much difference in voltage. 

Myself, I don't think the divergence in cell voltages on the exponential part of the charging curves really tells you much about how the cells behave over the rest of their SoC, it is just a convenient way to balance - and I don't think of them as really perfectly balanced since internal cell conditions on that part of the curve are different than over the rest of their operation. I think it just gets them close to operating the same over the rest of their operating space.


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## tomofreno (Mar 3, 2009)

JRP3 said:


> That's one way, the other is to check during charge and see if the finish voltage changes between cells. Just because a pack isn't top balanced doesn't mean the cells don't have specific voltages when charging.


 Yes, but it does mean the difference in cell voltage will be much smaller for a given difference in SoC, possibly leading you to conclude there is no significant difference in SoC, whereas you would see it if all were driven into an exponential part of the curve. The "drift" people mention is typically less than an Ah or so, not easily detected by cell voltage differences unless cells are on an exponential part of the curve. These small "drifts" have no practical consequence while driving. I have one cell that has typically been 1 - 2 Ah or so lower SoC than all the rest for almost 3 years now. It has had no effect on driving since I never go below about 28% pack SoC.


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## dtbaker (Jan 5, 2008)

JRP3 said:


> I wonder if top balanced cells are more prone to drifting apart than bottom balanced? I think most of us with bottom balanced packs don't see much drift.



I have not seen any significant drift after 8k miles on a BMS-less top balanced pack. It is key I think if you are going to top balance to do a really good initial balance a little above where you plan to charge to so that the normal charge cycle trips from ca->cv and ends when all cells are very close to same vpc.


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## ElectriCar (Jun 15, 2008)

dtbaker said:


> I have not seen any significant drift after 8k miles on a BMS-less top balanced pack. It is key I think if you are going to top balance to do a really good initial balance a little above where you plan to charge to so that the normal charge cycle trips from ca->cv and ends when all cells are very close to same vpc.


I think what's happening in your case is you have a pack with very good internal resistance, closely matched. I think where mine vary so much is due to the IR varying. Though each was marked with ah and ir on the shipping papers, their behavior doesn't match the papers or doesn't match what I think I should see. 

Ie if you have one cell with a high IR, the voltage across it will be higher than the others when it's charging because voltage = amps times resistance. I really don't have a solid understanding of these batteries though when it comes to how the IR affects the charge of individual cells and how their behavior affects others in the pack. It's a big mystery to me even though I totally understand how resistance, current and voltage work in a circuit. A battery is not the same as resistive load.


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## drgrieve (Apr 14, 2011)

tomofreno said:


> I think that is the difference. Most, if not all cells in a top balanced pack are driven up into the exponential part of the curve each charge where change in voltage with Ah added is much greater, magnifying small differences in SoC. The cells in my pack show the same voltage to within a few mV during most of the charge, until around 3.44V or so where some start to increase a bit faster in voltage than others. I recently did some work on my pack heaters and had the bms boards disconnected from some of the cells for several days. Even with around 2Ah difference in SoC of these cells from the rest, all cell voltages were about the same until around 3.44V where these cells started quickly pulling ahead in voltage as they entered the exponential part of the curve while the others had not. If the pack is bottom balanced you likely won't see any difference in cell voltage if all cells are below 3.44V when charging is ended. I think you would have to monitor cell voltages while driving with cells at 25% or less SoC to see much difference in voltage.
> 
> Myself, I don't think the divergence in cell voltages on the exponential part of the charging curves really tells you much about how the cells behave over the rest of their SoC, it is just a convenient way to balance - and I don't think of them as really perfectly balanced since internal cell conditions on that part of the curve are different than over the rest of their operation. I think it just gets them close to operating the same over the rest of their operating space.


This is not a indication of SOC or an indication of "top-balance". This is an behavior of diffusion, as the cells become full, some cells can intercalate the lithium ions faster than the other cells. This shows up as a higher voltage but in no way shows the cells SOC compared to another.

To measure a cells SOC using voltage, the voltage must be static ie at rest for many hours (or even days.) The charging voltage is not real, and is not an indication of SOC as it is effected by many variables. Top balancing using charging voltage is wrong.


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## JRP3 (Mar 7, 2008)

Well it certainly is an indication of SOC, though maybe not an exact one. I suspect it's probably good enough since most, if not all, OEM EV's use voltage during charging to determine SOC and top balance the pack.


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## corbin (Apr 6, 2010)

dtbaker said:


> I have not seen any significant drift after 8k miles on a BMS-less top balanced pack. It is key I think if you are going to top balance to do a really good initial balance a little above where you plan to charge to so that the normal charge cycle trips from ca->cv and ends when all cells are very close to same vpc.


I think eventually this could get you in trouble!

I have one of my 48 cells starting to die. It is the first cell to start hitting low voltages (and always the first to sag under load). It is also the first cell to be fully charged, and has higher resistance than all other cells. 

If I was not using a BMS, I would have been overcharging this cell. All the other cells have a fairly low voltage, and this one (over time) started getting higher than the others during normal charge cycles. 

My pack has nearly 20,000 miles. At 8k miles I wasn't having any drift. 

Mainly I mention this to illustrate that having little drift over 8k might not mean much in the long run! I think a BMS is a good safety measure to tell you when to start and stop charging (and to monitor each cell's voltage).

-corbin


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## drgrieve (Apr 14, 2011)

JRP3 said:


> Well it certainly is an indication of SOC, though maybe not an exact one. I suspect it's probably good enough since most, if not all, OEM EV's use voltage during charging to determine SOC and top balance the pack.


They are still doing it wrong or perhaps only applicable to LiFePo4 - I only follow that chemistry.

Say you are doing a fast charge at 0.5C and are now tapering down.

Cell 1 is at 180 ah / 205 reported voltage is 3.62V
Cell 2 is at 190 ah / 200 reported voltage is 3.59V

Notice a problem?

Voltage near the end of capacity (especially at higher C rates) for individual cells is all over the place. Up, down, where ever -> shunting when your cells voltage is not an accurate indication of charge is pretty silly.

Here is a chart from John Hardy:










Anyway like discharging, charging should be done away from the knee.


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## Ziggythewiz (May 16, 2010)

drgrieve said:


> Notice a problem?
> 
> Anyway like discharging, charging should be done away from the knee.


No, because if they're top balanced they'll be closely matched when they get that high, not all over as they are if bottom balanced. 

If you're below the knee there's no chance for scatter. All the OEMs, and most BMS free top balancers don't charge into the knee, so no scatter and no worries.


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## GizmoEV (Nov 28, 2009)

Ziggythewiz said:


> No, because if they're top balanced they'll be closely matched when they get that high, not all over as they are if bottom balanced.
> 
> If you're below the knee there's no chance for scatter. All the OEMs, and most BMS free top balancers don't charge into the knee, so no scatter and no worries.


Look carefully at the graph again. Pick any place to normalize (ie balance) the cells at and you will have an imbalance of voltages at every other place. Furthermore, based on observations of my pack, it isn't always the same cells which hit the top first. Not only are the diffusion rates different between cells, the diffusion rates appear to change from one charge to the next. The only way to get away from this is to match a set of cells at the bottom, where no current is flowing for a long time. Top balancing on every charge actually will change the balance between cells each time, it is just that those who are using a top balancing BMS won't know about it. They probably don't really care either since the change in balance will be minimal anyway.


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## JRP3 (Mar 7, 2008)

drgrieve said:


> They are still doing it wrong or perhaps only applicable to LiFePo4 - I only follow that chemistry.
> 
> Say you are doing a fast charge at 0.5C and are now tapering down.
> 
> ...


Yes, you should have tapered current well before that, those aren't realistic values. You don't shunt at high C rates. Also, OEM's probably have more closely matched cells for capacity and resistance.





> Anyway like discharging, charging should be done away from the knee.


You need to at least get into the beginning of the knee.


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## ElectriCar (Jun 15, 2008)

corbin said:


> I have one of my 48 cells starting to die. It is the first cell to start hitting low voltages (and always the first to sag under load). It is also the first cell to be fully charged, and has higher resistance than all other cells.
> 
> 
> -corbin


So what are you using to monitor each cell, cell log 8's or such? I've resisted doing any of that but I may do something like that since I'm seeing the same thing, ie certain ones emptying first and reaching recharge first, see my last file upload.


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## Ziggythewiz (May 16, 2010)

GizmoEV said:


> Look carefully at the graph again. Pick any place to normalize (ie balance) the cells at and you will have an imbalance of voltages at every other place.


Not quite. If you match them at one end, they will be ragged at the other, but together most of the way between. There can be no raggedness in the 20%-80% SOC range.

As Dan said, if you top balance at a higher level than your daily charge and stay out of the bottom 20%, you won't see any differences unless you have a failed cell.





JRP3 said:


> You need to at least get into the beginning of the knee.


You have to get into A knee to balance. You don't ever have to return to the knee unless you need that full or nearly full range. The cells would lead a perfectly happy life never running up or down a slope again.





ElectriCar said:


> So what are you using to monitor each cell, cell log 8's or such? I've resisted doing any of that but I may do something like that since I'm seeing the same thing, ie certain ones emptying first and reaching recharge first, see my last file upload.


If you want some monitoring, but don't want to go full cell-log you can do a Lee Hart battery bridge, or just half pack (I'm doing thirds because of my cell makeup) DVMs. When you see a difference you know there's an anomaly. If you don't need to dry that sponge you can simply reduce your charge regimen to slightly before the anomaly without having to rebalance.


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## JRP3 (Mar 7, 2008)

"Knee" is a pretty vague term. You need to charge to an increasing voltage unless you don't care if you're 50% charged or 80% charged.


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## EVfun (Mar 14, 2010)

drgrieve, voltage at a specified current is how the manufacturer specifies a full charge. It works fine for LiFePO4 cells. Internal resistance and diffusion rates are not a significant issue because the discharge currents are SO much higher that the cell will have failed for EV applications long before it makes much difference on charge. 

I discharge at 300 amps peak (if I'm nice.) I terminate charge at less than 6 amps. If a cell of mine had 0.003 ohms of impedance it would be no good to me as it would fall under 2.5 volts from the first full throttle stab. At 6 amps the effect on cell voltage is less than 0.02 volts, well within accepted variation for charging.


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## GizmoEV (Nov 28, 2009)

Ziggythewiz said:


> Not quite. If you match them at one end, they will be ragged at the other, but together most of the way between. There can be no raggedness in the 20%-80% SOC range.


You aren't reading it right. The voltage difference under charge and high voltage is significant compared to after the charging stopped. If you balance during this point you will be pushing the cells further out of balance. The balance also will be changing from one charge to the next. I've seen it happen on my pack.


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## Ziggythewiz (May 16, 2010)

GizmoEV said:


> The balance also will be changing from one charge to the next. I've seen it happen on my pack.


I'm not balancing every charge. I top balanced once, and never take the cells that high again. There's no way for the balance to change.

And no, the voltage under charge and at rest is not that different if you're slow charging and not taking them over 3.4vpc.


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## JRP3 (Mar 7, 2008)

Actually there is, though it may be too small to notice. Since during discharge and charge you are taking the same amount of current out of each cell or putting the same amount back in the different effective levels of cell resistance has to create some imbalance. By undercharging we may not see the differences, but at some point I do expect to have to rebalance my pack.


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## EVfun (Mar 14, 2010)

I don't believe so JRP3. Cells store amp hours, each electron moves a Lithium ion. So while slight differences in internal resistance may cause the voltage to be slightly different, the amount the battery is discharged or charged is the same for all cells in a series string. This is why the best EV fuel gauges generally come from amp hour based counting systems.


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## JRP3 (Mar 7, 2008)

Internal resistance causing voltage differences comes from losses, those losses have to come from something, and it has to be capacity. Those ions have to find a place to go, (intercalate), and the more internal "resistance" the more time they spend bouncing around looking for a home.


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## EVfun (Mar 14, 2010)

Internal resistance is causing voltage differences. The losses are coming from something -- the *difference* in voltage times the current. It does not cause amp hour differences between cells so it is not changing the rate the cells charge or discharge.

If you have 2 cells in series charging at 10 amps and one is at 3.40 while the other is at 3.42 then the second cell has 0.2 watt higher losses. Both cells are adding amp hours at the same rate as both cells are receiving the same number of electrons. The second cell happens to be receiving 0.2 watt more because the voltage across it is higher. It is heating slightly more. 

This bouncing around stuff is just an oversimplified explanation. When you charge you take an electron off the positive plate and add it to the negative one. The Lithium is only in ion form in the electrolyte as a means to allow the Lithium atoms in each plate to cross to the other side. So when you take that electron off the positive plate it rejects a Lithium atom that just became a Lithium ion due to electron loss. The negative plate sucks up a Lithium ion from the electrolyte to satisfy the electron that just landed on the plate. The concentration of Lithium ions in the electrolyte didn't change. 

There is so little of an issue with side reactions that LiFePO4 cells have proven quite resistant to cell drift. Lead acid cells electrolyze water as a side reaction. That energy doesn't go into charging (moving sulfate ions) so these cells suffer from constant drift largely driven by small voltage differences.


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## JRP3 (Mar 7, 2008)

EVfun said:


> If you have 2 cells in series charging at 10 amps and one is at 3.40 while the other is at 3.42 then the second cell has 0.2 watt higher losses. Both cells are adding amp hours at the same rate as both cells are receiving the same number of electrons. The second cell happens to be receiving 0.2 watt more because the voltage across it is higher. It is heating slightly more.


You're saying both cells are getting the same amount of energy but one of them is losing more of it to heat, so how can they be storing the same amount of energy if one has higher losses?


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## EVfun (Mar 14, 2010)

No, the cells are receiving different amounts of energy, but storing the same amount. The cell at 3.40 volts is receiving 34 watts and the cell at 3.42 volts is receiving 34.2 watts. The extra is lost as heat.


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## GizmoEV (Nov 28, 2009)

EVfun said:


> No, the cells are receiving different amounts of energy, but storing the same amount. The cell at 3.40 volts is receiving 34 watts and the cell at 3.42 volts is receiving 34.2 watts. The extra is lost as heat.


That is exactly right. I think that sometimes where the confusion comes in is when we refer to an Ah/mi figure for our particular setup. We unintentionally give people, sometimes our selves, the impression that an Ah is a measure of energy when it is not. It is literally a measure of the number of electrons that have been moved.


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## GizmoEV (Nov 28, 2009)

Ziggythewiz said:


> I'm not balancing every charge. I top balanced once, and never take the cells that high again. There's no way for the balance to change.
> 
> And no, the voltage under charge and at rest is not that different if you're slow charging and not taking them over 3.4vpc.


Now you are changing the question. Go back and look at that graph and note the voltages. Furthermore, as others have pointed out, because of differences in diffusion rates, balancing to a given voltage at any point along the charge curve will cause an imbalance, regardless of the voltage.


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## EVfun (Mar 14, 2010)

But charging to a given point along the charge curve is usually the definition of "full charge." That point usually being given as 3.65 volts at 0.05C amps. 

It would be great if we could count the Lithium atoms in each side to determine full charge. Perhaps it would be something like, "charge until the number of Lithium atoms in the graphite is 10x the number remaining in the Iron Phosphate." Beyond that point the charge voltage goes to high at 0.01C current (1% per hour charge rate.) Since that is not realistic we have to use either; some set point on the voltage/current charge curve (generally a low current point so impedance isn't a significant issue), or the no load voltage after a few days rest (not practical in service.)


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## Ziggythewiz (May 16, 2010)

GizmoEV said:


> Now you are changing the question. Go back and look at that graph and note the voltages.


Which graph are you referring to? The one from John Hardy testing cell drift in a bottom balanced pack?




EVfun said:


> It would be great if we could count the Lithium atoms in each side to determine full charge.


Even if you could count the atoms, it wouldn't help because each cell will have a different number of atoms/ions on each side. All that matters is that a cell is considered full after holding 3.65 vpc @ .05C, giving a resting voltage near 3.4 (per manufacturer instructions, which become more conservative every release).

Full is full regardless of whether it's 90AH or 110AH. Top balancing seeks to make all cells full (balanced per voltage) and keep all cells the same distance (not %) from full.

I use mine from 30-90% est SOC. Do I really know they're in that range? No, because verification would require regularly doing 100-0%, which would be counterproductive.


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## GizmoEV (Nov 28, 2009)

Ziggythewiz said:


> Which graph are you referring to? The one from John Hardy testing cell drift in a bottom balanced pack?


Yes. Look at the voltages as the charge continues and then ends. The different cells even move relative to each other during the charging and after the charge terminates.


As for counting electrons/ions it wouldn't matter what full is. Just transfer the number for the lowest capacity cell. I suspect, however, if we could readily do the counting that we could also watch the degradation of the cell. That would really be handy.



Ziggythewiz said:


> Full is full regardless of whether it's 90AH or 110AH. Top balancing seeks to make all cells full (balanced per voltage) and keep all cells the same distance (not %) from full.


The problem is that for those who top balance, especially on every charge, that the charge current is way below 0.05C while the voltage is still in the 3.60-3.65V range. This over charges the pack.

That being said, because of the charger I have, which I can't terminate based on voltage AND current, I top balanced my pack at 4.00V which is what my BMS boards are set to, and then removed the boards. Before I decide to use them again I'll be having them adjusted down. I have been monitoring my pack voltage immediately after charge and I see the same thing that John Hardy's graph shows: the cells trading places. I'm currently only charging to 3.455vpc. I presume that I will see a critical imbalance before it gets out of hand but again that is a presumption.


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## Ziggythewiz (May 16, 2010)

GizmoEV said:


> Yes. Look at the voltages as the charge continues and then ends. The different cells even move relative to each other during the charging and after the charge terminates.


Of course they move significantly at the top if they are bottom balanced, but that is irrelevant to top balancing.



GizmoEV said:


> The problem is that for those who top balance, especially on every charge, that the charge current is way below 0.05C while the voltage is still in the 3.60-3.65V range. This over charges the pack.


Agreed. Balance once, don't take the cells that high again, stay out of the bottom 20-30% and do some form of limited comparison monitoring.


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## JRP3 (Mar 7, 2008)

EVfun said:


> No, the cells are receiving different amounts of energy, but storing the same amount. The cell at 3.40 volts is receiving 34 watts and the cell at 3.42 volts is receiving 34.2 watts. The extra is lost as heat.


Don't know why I didn't realize that before


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## GizmoEV (Nov 28, 2009)

Ziggythewiz said:


> Of course they move significantly at the top if they are bottom balanced, but that is irrelevant to top balancing.


They move significantly at the top whether top or bottom balanced. John's graph shows that and my experience watching my pack top balance, when I did it on every charge, also showed the same type of thing. Look at the spread before the "knee" and after the charging stopped. Note the small differences in voltages. Then compare that to the differences between those points. The difference between is not all due to SOC differences. It is largely due to diffusion rate differences.


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## Ziggythewiz (May 16, 2010)

GizmoEV said:


> They move significantly at the top whether top or bottom balanced. John's graph shows that and my experience watching my pack top balance, when I did it on every charge, also showed the same type of thing. Look at the spread before the "knee" and after the charging stopped. Note the small differences in voltages. Then compare that to the differences between those points. The difference between is not all due to SOC differences. It is largely due to diffusion rate differences.


I'll repeat: Do it once, and don't go that high again.

Diffusion rates are irrelevant after a few hours, and most of us leave them paralleled for a day or more before we get around to disconnecting them all.


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## GizmoEV (Nov 28, 2009)

Ziggythewiz said:


> I'll repeat: Do it once, and don't go that high again.
> 
> Diffusion rates are irrelevant after a few hours, and most of us leave them paralleled for a day or more before we get around to disconnecting them all.


I think you forgot what the original question was. I haven't balanced my pack for over a year so I don't do it all the time. Repeating to do it once avoids the question of whether top balancing really matches up the SOC of the cells. If using the plethora of shunting BMS systems to do it, it doesn't look like there is a very high probability of getting them balanced as close as a good bottom balance does. Paralleling and charging to a high voltage helps but then there is no guarantee that each cell will actually be at the same SOC since current flow between cells decays exponentially as voltage difference decreases. Balancing at the bottom where cells are left unconnected to any thing else, even other cells, has a much better chance of matching up SOC. You could bottom balance a parallel set, let them sit for a while, then disconnect them and check each cell after a few days and make individual adjustments as needed. That is something you can't do at the top.


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## EVfun (Mar 14, 2010)

My shunting BMS didn't do a great job of top balancing either. I had to tune them up with a couple power resistors for about 10 charges after removing the regs. At some point close enough is good enough. The total scatter at the end of charge, measured with the charger in the last 2 minutes of run time, is 3.47 to 3.56 vpc. The high cells are consistently high, the low consistently low*. It seems to be close enough. They all read 3.35 volts the next day. I'm pretty sure the loss of one cell, even it going dead and staying at 0 volts throughout a charge, would not allow any other cell to exceed 4.0 volts. That is what I'm after with top balancing, some level of failure resistance.

A form of top balancing is how most manufacturers *define* full charge. It is typically 3.65 volts at 0.05C. That could be done individually to all the cells with a single cell charger before assembling a pack. They don't appear to have any self discharge and all the cells could be topped off a second time in a matter of hours with the charger after the pack is assembled but before it sees first load. I would be inclined to use that method on a future pack, instead of using shunt regs and then removing them. 

* I do have some issues with 6 added cells creeping up on the rest, at least for their first year added to the existing pack. It is easy to knock them down about 0.25 amp hour when they get to about 3.7 volts at the end of charge. If this doesn't go away next year I will likely go back to shunt regs on all the cells. It worked fine for me. The mild 1/2 amp shunt got them close enough to equal that no cell ever got to 3.7 volts. The high cells kinda danced around the pack from cycle to cycle, or so it seemed.


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## ElectriCar (Jun 15, 2008)

I have about 4 cells which I must drain off EVERY TIME I top balance. It isn't much but it's enough that when approaching an average of 3.4 VPC they will spike. Since overcharging causes plating of the anode or cathode, I forget which, leading to reduced capacity, I want to stay out of that area. To minimize the odds of this happening I've lowered the charge voltage to 169.4 or 3.39VPC where it was 171.1 or 3.422VPC. 

The amount of Ah lost is nothing, maybe half a mile, 1Ah. Well from 3.4 to 3.39 the calculated pack Kw is 33.9, down 100watts from 3.4V. I'm not concerned in the least about squeezing every last tenth of a mile out of my pack or even mile. I sized it to give me 100 miles and I can do more than that. My concern is longevity and at this point I have almost 11,000 on my BMS-less pack without a single cell failure.

On Monday I drove 70 miles mostly on the interstate which took 21.78Kw to replenish the pack. At that rate I could go around 109 miles, assuming my cells can still hold 200Ah and I ran the well dry. Even so, the pack is not bottom balanced so I wouldn't get that far realistically. 

So it would appear that if you're BMS-less as many are and also maximizing your charge for that extra half mile of capacity, in time you're going to lose more than what you're currently gaining due to that lost capacity in some cells. Just as a chain is only as strong as the weakest link, a pack's AH capacity is only as much as the lowest cell capacity.


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## 1-ev.com (Nov 4, 2010)

ElectriCar said:


> On Monday I drove 70 miles mostly on the interstate


Do you using any additional cooling on the motor or factory internal fan is sufficient?

Thank you, -Y.


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## ElectriCar (Jun 15, 2008)

Factory fan is ok but it will get hot. Search the insulating rating on your motor. Mine is H which is good for 180C. That's very hot! It will get hot and you'll smell it the first time you heat it up but that doesn't mean it's damaged. 

I've been keeping the RPM up over 3000 when I can but I don't like to run it that fast. I just recently installed a temp sensor on the motor to keep tabs on it. It barely moves the needle on my temp gauge and with an IR thermometer it reads only about 130F. I have seen it as high at 165F or so but still, nowhere near the rating of the motor.


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## dougingraham (Jul 26, 2011)

ElectriCar said:


> I have about 4 cells which I must drain off EVERY TIME I top balance. It isn't much but it's enough that when approaching an average of 3.4 VPC they will spike. Since overcharging causes plating of the anode or cathode, I forget which, leading to reduced capacity, I want to stay out of that area. To minimize the odds of this happening I've lowered the charge voltage to 169.4 or 3.39VPC where it was 171.1 or 3.422VPC.


The four replacement cells must be displaying a difference in the charge diffusion delay that is different from the older cells. A manual top balance would probably correct this.

If you try to top balance the only way I can see to get a real balance is to use a dvm that can has a resolution of 0.0001 volts on the scale that will display a single cell voltage. Charge it up and then after a half an hour resting check the voltages of every cell. Add a little charge to the low ones and remove a little from the high ones. Repeat until you are happy with the balance. I would attempt to get better than 0.001 volts. Near the 50% SOC point a resting voltage difference of 0.0004 volts is equal to about 1% SOC. It is better near the ends both top and bottom.

Shunt balancers can work but not while you are charging and certainly not when the voltage is above 3.4 volts on a cell. And shunt balancers are not accurate enough to get a good balance. If you use a single device like a DVM you don't care about the accuracy, just the differences between the cells. And with a single reference in the DVM that is what you get. With an analog shunt the reference is often a zener diode. Unless you spend quite a lot the accuracy is perhaps as bad as 5%. With a digital device like an Arduino or pretty much any of the single chip cpu's a 10bit A/D is not good enough. The references in these devices are about 1% but 10 bits if scaled from 0-3.6 volts would give a resolution of 0.0035 volts and without using statistical techniques they are really only 9 bits making this only good to 0.007 volts. A 3.4 volt reference could be seen as low as 3.366 or as high as 3.434. An external 0.1% reference would be essential to making this work properly in addition to at least a 12 bit A/D.

The non BMS people use a single reference high resolution device (DVM) to do their balance. They generally balance to within a couple of thousandths which is far better than the shunt balancers can do even if they were balancing when it makes a difference which is not when charging and the cell voltages are above 3.4 volts when the voltage is a display of charge diffusion delay rather than an indicator of state of charge. Either top or bottom the manual balance is far better than the analog or cpu driven shunt balancers can do.


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## dtbaker (Jan 5, 2008)

ElectriCar said:


> I have about 4 cells which I must drain off EVERY TIME I top balance.


 I am a little surprised they creep back up relative to the rest of the pack.... unless they are a different age/batch than the rest of the pack?

When you drain off a little from these cells, how do you do it, how much do you pull out, and do you have any suspicions on how they are drifting back higher relative to the pack?



ElectriCar said:


> I've lowered the charge voltage to 169.4 or 3.39VPC where it was 171.1 or 3.422VPC.


I don't think you'll get a good charge with that low a cut-off.... you are BARELY out of the flat part of the curve, and your charger may be stopping prematurely as soon as just a couple cells just start climbing. You need to get at the root of the problem and figure out why those four are drifting... 



ElectriCar said:


> My concern is longevity and at this point I have almost 11,000 on my BMS-less pack without a single cell failure.


sounds good. I have not had any problems either. In fact, no significant drift even in 15,000 miles. I have cut back to checking only perhaps annually. How often do you check, and HOW do you check balance? Just after charge finishes, or ?


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## EVfun (Mar 14, 2010)

ElectriCar said:


> I have about 4 cells which I must drain off EVERY TIME I top balance. It isn't much but it's enough that when approaching an average of 3.4 VPC they will spike. Since overcharging causes plating of the anode or cathode, I forget which, leading to reduced capacity, I want to stay out of that area. To minimize the odds of this happening I've lowered the charge voltage to 169.4 or 3.39VPC where it was 171.1 or 3.422VPC.


At least I'm not the only one who has seen some type of balance creep in use! Thanks for sharing your experience. It seems similar to what I've observed with 6 added cells.

What rate do you charge at? I typically charge at 0.2C (12 amps on 60 amp hour cells) and I don't think I could cut off at less than about 3.45 volts. The cells hang out around 3.4 volts for some time. I'll have to time it and see how long.


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## dtbaker (Jan 5, 2008)

EVfun said:


> ... seems similar to what I've observed with 6 added cells.



aha.... so the creepers are of different age/batch compared to remainder of pack?

fits with the general caution about mixing newer batteries into an existing pack. possible, but means you'll probably have a bit more checking/balancing required to keep them all in line.


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## EVfun (Mar 14, 2010)

dtbaker said:


> aha.... so the creepers are of different age/batch compared to remainder of pack?


No, I purchased 42 Thunder Sky 60 amp hour cells. The cells I received where from a single batch made in late February 2010 (I actually received my cells from EVC.) In 2010 I used 40 cells in an old Datsun. Over the winter I sold the Datsun without the EV parts and installed 32 cells in my EV Buggy. I drove the Buggy around that way in 2011. Then over the winter I installed 6 additional cells from the old Datsun pack and drove the Buggy with a 38 cell pack in 2012. Now I am reconfiguring the buggy again and will have 39 of the cells that where in the Datsun in the Buggy this year.


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## GizmoEV (Nov 28, 2009)

dtbaker said:


> I don't think you'll get a good charge with that low a cut-off.... you are BARELY out of the flat part of the curve, and your charger may be stopping prematurely as soon as just a couple cells just start climbing. You need to get at the root of the problem and figure out why those four are drifting...


That depends on the charging current at the end of charge. If it is low enough it won't make much difference. I've measured it my self.



dtbaker said:


> aha.... so the creepers are of different age/batch compared to remainder of pack?
> 
> fits with the general caution about mixing newer batteries into an existing pack. possible, but means you'll probably have a bit more checking/balancing required to keep them all in line.


I've been thinking that when I finally get to convert a rig that if I can't get the pack size I want initially then I should build it so I can double the pack by paralleling the cells like I did in my Gizmo. Parallel an old cell with a new one and maybe the "drifting" will be kept in check and will be the same across all cell pairs.


@ElectriCar: What speed were you going on the highway when you did that 70 miles. Also you said it took 21.78kWh to replenish the pack. Was that measured at the battery or from the wall? I'm trying to get an idea of what I'd be looking at for a 150mi S10 at 60mph.


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## ElectriCar (Jun 15, 2008)

dougingraham said:


> The four replacement cells must be displaying a difference in the charge diffusion delay that is different from the older cells...


No, no cells were ever replaced. All original and not in any particular location, some are in the middle with one on the outside row.


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## ElectriCar (Jun 15, 2008)

dtbaker said:


> I am a little surprised they creep back up relative to the rest of the pack.... unless they are a different age/batch than the rest of the pack?
> 
> When you drain off a little from these cells, how do you do it, how much do you pull out, and do you have any suspicions on how they are drifting back higher relative to the pack?
> 
> ...


I use 6V emergency light lamps in parallel for draining. And it works pretty fast as they are over 3.4V or so when I drain them.

What I suspect is happening is due to internal resistance of those cells. I understand ohms law but not so much when applying it to battery charging.

Re not fully charging, when they rest at 3.4V they are fully charged correct? When they're all balanced near 3.4V, they are all practically fully charged with my charger as evidenced by trying to charge them more. They won't take maybe half an Ah, and that is nothing in the scheme of things. When my Zivan NG5 charger gets to the CV portion of the charge, it will trickle the current down to just 0.1A, maybe lower but my meter won't register it and hold the voltage there until it times out. 

I just check them periodically, can't give you a mileage but I've gone over a thousand , maybe two thousand miles without checking them. Today I worked on it a bit but I really need to do a good balance again with the charger near the end of the CV phase and start a periodic recheck at predetermined mileage intervals.


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## ElectriCar (Jun 15, 2008)

GizmoEV said:


> That depends on the charging current at the end of charge. If it is low enough it won't make much difference. I've measured it my self.
> 
> 
> 
> ...


Speed was probably an average of 55. And it was from the wall, the CA was about 19,500 but I'm not sure if I had zero'd it before that run as it was off showing about -0.4A when current was zero, throwing the CA off.

Oh and today I finally go my balance meter operable today. I had damaged it before because it wasn't an isolated meter so I put an isolated DC-DC 5V converter in and it works finally, showing 0.00-0.01 which I verified with a meter.


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## JRP3 (Mar 7, 2008)

Charging to an ending current as low as .1A seems much too low a current. I think you risk overcharging the cells since that's basically trickle charging, and probably why you are seeing some cells shoot up. 3.4V resting is fully charged but you're better off undercharging them slightly for greater cycle life.


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## ElectriCar (Jun 15, 2008)

It only does that to maintain the voltage setpoint. At 3.4V for example if you were charging one cell, once the cell voltage = the applied voltage, current would stop. If it dips a bit a little current would flow again.


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## JRP3 (Mar 7, 2008)

Maintaining the voltage set point by trickle charging is the problem. You don't want to fully charge the cells and the charger should just shut off at some point, not keep dropping current to a miniscule amount, or shutting of and coming back on. You don't want to float lithium cells, which is what you seem to be describing. 
My normal charging is at 20 amps for my 100ah cells until average cell voltage hits 3.42V, then the charger just shuts off. I've eliminated the CV stage to keep my cells under charged. If I want more range for some reason I'll allow the CV stage but only down to 5 amps or so, though I can't remember the last time I even bothered. For longest pack life you want to undercharge your cells.


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## ElectriCar (Jun 15, 2008)

3.4V is fully charged I thought. So long as the cell voltage doesn't settle above that, it can't be overcharged, thus my turning the voltage down to 3.39VPC as insurance. 

So how can I overcharge if I'm stopping at the setpoint of 3.4 or 3.39 WITH A BALANCED PACK? The charger can't FORCE current into the pack, current will only flow when the voltage of the pack is less than what's set on the charger. Once they are the same, it's impossible for current to flow per Ohms law. Or am I missing something???


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## jddcircuit (Mar 18, 2010)

dougingraham said:


> If you try to top balance the only way I can see to get a real balance is to use a dvm that can has a resolution of 0.0001 volts on the scale that will display a single cell voltage. Charge it up and then after a half an hour resting check the voltages of every cell. Add a little charge to the low ones and remove a little from the high ones. Repeat until you are happy with the balance. I would attempt to get better than 0.001 volts. Near the 50% SOC point a resting voltage difference of 0.0004 volts is equal to about 1% SOC. It is better near the ends both top and bottom.


I am not sure I agree with this being the way to get a real balance. My definition of top balance means that each cell will enter and track into the upper knee at the same time while being charged as a pack under a constant current supply.

I never really seem to have a need to measure the resting voltages like you suggest when I perform alignment. However, it does seem to matter how much rest time the cells have and the similarity of SOC when I start to apply a constant current and terminate at a fixed voltage up the the knee ONE cell at a time. I always align one cell at time and I avoid all constant voltage and shunt regulating methods during this alignment process.

I have seen some improvement in the voltage profile alignment at the top with a couple iterations of partial pack discharge, rest, and single cell top align if the cells are way out of balance.

I would do the same thing in reverse if I was bottom balancing.

I am experimenting with different conditions (i.e. current and single cell threshold voltage) but this is basically what I am doing at the moment.

cheers


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## dtbaker (Jan 5, 2008)

EVfun said:


> Then over the winter I installed 6 additional cells from the old Datsun pack and drove the Buggy with a 38 cell pack in 2012. Now I am reconfiguring the buggy again and will have 39 of the cells that where in the Datsun in the Buggy this year.


my point is that some of the cells have different numbers of charge/use cycles.... 'age' not on the shelf, but in use; my hypothesis is that the resistance may change a little over USE, and so mixing cells with different history would most likely result in wider drift than a pack where all the cells have the same history.


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## dtbaker (Jan 5, 2008)

ElectriCar said:


> So how can I overcharge if I'm stopping at the setpoint of 3.4 or 3.39 WITH A BALANCED PACK?


two questions remain.... how balanced did you get them initially? i.e. I am finding that top balance in series did a decent job, but not super. I think because of the resistance in the small wire I used to wire them in parallel. Even though I let it chug along till current was 0, I think there may be enough resistance and self-discharge above resting voltage that parallel top balance is not as good as a highly regulated individual cell charge to set voltage.

I am in the middle of putting together a high current 12v power supply and an accurate charge controller to do individual cell top balncing to see how that goes.

The issue with THINKING cells are 'full' at 3.4 is that because you've barely left the flat part of the curve, the capacity difference from cell to cell could be significantly more than if they are balance higher up the curve.


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## JRP3 (Mar 7, 2008)

ElectriCar said:


> 3.4V is fully charged I thought. So long as the cell voltage doesn't settle above that, it can't be overcharged, thus my turning the voltage down to 3.39VPC as insurance.
> 
> So how can I overcharge if I'm stopping at the setpoint of 3.4 or 3.39 WITH A BALANCED PACK? The charger can't FORCE current into the pack, current will only flow when the voltage of the pack is less than what's set on the charger. Once they are the same, it's impossible for current to flow per Ohms law. Or am I missing something???


The point is you seem to be pushing the envelope. 3.40V is a fully charged cell voltage at a specific temperature, probably 70F or so. Fully charged means all ions are fully intercalated with no empty spaces, continued current flow even at low levels means you are trying to force more ions into the crystalline matrix and there is no place for them to go. Over time this could lead to cumulative damage, plus the fact that we know cells last longer not being fully charged. I think the reason you keep seeing some cells driven to higher voltages even with low currents and a "balanced" pack is because they are so completely close to full it doesn't take much for the differences in internal resistance and capacity to throw things off when a cell is so close to full even at low currents. Balance is relative and can only be so exact. Just to be clear charging to 3.45V at 20 amps and stopping under charges the cell where charging to 3.40V and holding it there while trickling down to 0.1 amps takes it right up to full. Throw in some variation in cell construction and voltage monitoring devices, and temperature, and you could be overcharging the cell a little bit each time.


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## JRP3 (Mar 7, 2008)

dtbaker said:


> The issue with THINKING cells are 'full' at 3.4 is that because you've barely left the flat part of the curve, the capacity difference from cell to cell could be significantly more than if they are balance higher up the curve.


Actually 3.4V probably IS full if he's tapering the current down to the 0.1A level and holding it there.


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## ElectriCar (Jun 15, 2008)

JRP3 said:


> Actually 3.4V probably IS full if he's tapering the current down to the 0.1A level and holding it there.


Yes I think the instructions say to charge to 3.65V but that's not happening, ever! 

When the charger reaches the setpoint CV voltage, the cells aren't going to take any more current once they too are at that same voltage. So with a balanced pack at 3.39V, there can't be any overcharging. 

You do understand that in order for the battery to receive ANY current whatsoever, even .000001A, the charger voltage MUST be outputting a higher voltage than the battery voltage. If the battery or pack is at any given voltage and the charger is outputting the exact same voltage, current can't possibly flow, none, zero. 

However if they aren't balanced, overcharging will happen for sure to some cells IF the charger is outputting even 3.4VPC. Those that are a little high will go higher than 3.4 while the others lag. And that's a problem and thus why I lowered my charger setting a bit. I want to try and keep ALL of them from exceeding 3.4V at zero current flow. 

I may have to lower it to 3.38# if that's what it takes. So long as it doesn't severely cut into the Ah capacity I'm good with that, even 3-4 Ah cut I can live with because if I don't and continue to overcharge some, they are going to lose capacity anyway, and that's permanent!


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## JRP3 (Mar 7, 2008)

ElectriCar said:


> Yes I think the instructions say to charge to 3.65V but that's not happening, ever!


I think max charge voltage for CALB's is 3.6, but there are no instructions saying you should charge to that voltage, just that you can. Remember though the 3.6V number is at a specific C rate at a specific temperature.


> When the charger reaches the setpoint CV voltage, the cells aren't going to take any more current once they too are at that same voltage. So with a balanced pack at 3.39V, there can't be any overcharging.


Is your pack so perfectly balanced and your instruments so accurate that you guarantee no cell is going higher?


> You do understand that in order for the battery to receive ANY current whatsoever, even .000001A, the charger voltage MUST be outputting a higher voltage than the battery voltage. If the battery or pack is at any given voltage and the charger is outputting the exact same voltage, current can't possibly flow, none, zero.


Correct, but see my above statement.


> However if they aren't balanced, overcharging will happen for sure to some cells IF the charger is outputting even 3.4VPC. Those that are a little high will go higher than 3.4 while the others lag. And that's a problem and thus why I lowered my charger setting a bit. I want to try and keep ALL of them from exceeding 3.4V at zero current flow.
> 
> I may have to lower it to 3.38# if that's what it takes. So long as it doesn't severely cut into the Ah capacity I'm good with that, even 3-4 Ah cut I can live with because if I don't and continue to overcharge some, they are going to lose capacity anyway, and that's permanent!


The problem you still face is that the low currents your are using to finish your charge don't push the cell voltage into the knee of the curve. At 3.38V and low charge currents your cells could be showing the same voltage but be at different SOC. If you charged at higher currents and let the voltage climb above 3.4V you'd actually be charging your cells less and you'd be able to see if they are really balanced or not. I don't think you can really balance a pack at 3.38V.


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## drgrieve (Apr 14, 2011)

dougingraham post is bang on. Try to balancing during charging is trying to balance diffusion delay and other non SOC effects. Which is weird.

You are wanting to balance SOC at the top? Then you have to do that at static voltage.

One cell is 3.9 another is 3.7 another is 3.5. Which one is being overcharged? 

Answer - you dont know. 

Check the resting voltage. Fully charged is 3.38V. Aim for resting voltage of all cells to be 3.33 or 3.34 which is rule of thumb 95% SOC (Has anyone got good data on this!?!)

Experiment with a cell. Charge to a high resting voltage (3.37) 99% or so SOC, check capacity, recharge again to 3.37 and take out 5% AH. Use that as a top balance voltage target.

Then by experiment determine a charging recipe where your cells reach your static voltage target. That might be 3.65v @ 5% AH in amps for your pack. Whatever works for you.

The only important thing is the resting voltage. The individual charging voltage is meaningless, and not worth looking at, let alone trying to do something with it (perhaps to a point though for example a cell is grossly undersized to the rest of the pack).

The pack charging voltage is only used as a recipe it is not representative of SOC. But unless you are counting AH in an accurate way (and I'm not aware of this) it's all we've got.


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## GizmoEV (Nov 28, 2009)

Some may not know that the charger that ElectriCar, the Zivan NG5, and my Zivan NG1, and NG3, do not allow for terminating charge based on the current dropping to a particular level. Unless some external charge controller is used we are stuck with a charger which tapers the current to essentially zero A and holds it there until the "soak charge timer" times out. These chargers were made for other batteries like Lead Acid, NiCd, and NiFe. Even the time in this "soak" region of the charge curve varies depending on how long it took to get to that point.

Since we can't control ending current we are stuck with lowering charge voltage until we don't over charge the cells any more. I balanced my pack with my shunting BMS which was fixed at 4.00V shunting voltage with a maximum shunting current of 500mA. They turn on at 4.00V and back off at 3.97V. I did that 23 months ago. I have been slowly lowering the ending voltage and I'm at 69.1V for a 20 cell pair 200Ah TS pack. (The BMS boards were removed after balancing.)

I don't see any drifting in my pack. I haven't tried to end the charge at a higher voltage for quit a while. On my last check in May the high cell was at 3.473V and the low cells were 3.441V. These are not always the high and low cells. Sometimes they change. The largest spread of 0.047V was in June 2012.

Buy morning the pack is sitting 67.8-68V so I'm sure they are getting fully charged, possibly over charged. I don't know what is really happening with the true SOC with temperature variations so I might be over charging them slightly. Are there any documented differences in the resting OCV at 100%SOC between the various years of TS cells, SE cells, and the CALB CA series?


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## Ziggythewiz (May 16, 2010)

dtbaker said:


> The issue with THINKING cells are 'full' at 3.4 is that because you've barely left the flat part of the curve, the capacity difference from cell to cell could be significantly more than if they are balance higher up the curve.


The important part is to balance at a greater extreme than you plan to use. I only balanced mine to ~98%, but I only charge them to 90 or 95% so in regular use I'm even further into the flat part of the curve.




GizmoEV said:


> Are there any documented differences in the resting OCV at 100%SOC between the various years of TS cells, SE cells, and the CALB CA series?


I have SEs and CAs together in series. They are very close while under load, but when resting the OCV varies some primarily due to temp.


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## drgrieve (Apr 14, 2011)

GizmoEV said:


> Are there any documented differences in the resting OCV at 100%SOC between the various years of TS cells, SE cells, and the CALB CA series?


OCV is 3.38V which is derived from the voltage potential of the cell chemistry of the anode and cathode.

All LiFePo4 cells share this attribute.

The next question to ask would be does the 20% SOC and 80% SOC resting voltages change for different cells. 

I'm thinking this would be important to know 80, 90, 95 SOC for improving cycle life. If you know you're not going to travel far, charge to 80% and improve your cycle life 5X (from 2000 to 10000).


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## ElectriCar (Jun 15, 2008)

ElectriCar said:


> Last week I went down to 198 but kept a keen eye on the pack voltage. No it's top balanced but it won't stay balanced. Call it drift or whatever but there are certain cells that end up climbing higher than the others over time. They were actually marked shortly after the initial install. I've only balanced it about 2 times in the last 6-8000 miles or so I'm thinking.
> 
> If there's time I recharge until finished. You can see the VPC I charge to on the chart. It varies slightly with temperature but is safely under any danger of spiking cells.
> 
> Here's the discharge voltage for each cell at 198Ah from last time and the again after recharging along with the voltage change from empty to full.


Maybe this will help. This data was taken a few months ago. I'm planning to recharge my pack today then balance it again. You can see a big difference in the capacity of a few cells as they are the first to bottom out and the first to reach full charge.


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## ElectriCar (Jun 15, 2008)

Looking at that data, I can see that #43 is the worst, lowest capacity cell and #36 is the 2nd worst. I have one spare and may swap it with 43 to see what changes.


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## JRP3 (Mar 7, 2008)

GizmoEV said:


> Some may not know that the charger that ElectriCar, the Zivan NG5, and my Zivan NG1, and NG3, do not allow for terminating charge based on the current dropping to a particular level. Unless some external charge controller is used we are stuck with a charger which tapers the current to essentially zero A and holds it there until the "soak charge timer" times out.


Considering that then the best you can do is lower the ending charge voltage. At such low currents you really are ending up near resting voltage for the cells and you probably should be setting voltage at or below 3.38V per cell. Might be good to put an external timer on it that cuts all power to the charger after a while so it can't "soak" charge it for too long.


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## ElectriCar (Jun 15, 2008)

Ok just finished a charge and made some notes. This should put some theories to rest. 

I lowered the pack voltage to 169.4 last week giving me an average of 3.388VPC. *Some of you may have questioned/suggested I'm leaving a lot of power out of the batteries because they're not fully charged *so I adjusted the voltage up in increments then when the current went to nearly zero I noted the Ah put back into the pack.

First I increased it 0.3V to 169.7 or 3.394 Volts per cell. The current ramped quickly to about 6A then after only seconds it slowed to a trickle, 0.1A. The result? I added a whole 0.2Ah to the pack. 

Next I increased it 0.5V to 170.2 or3.406 VPC. Same thing current wise but this time it added .15Ah more. 

All told, from 3.388V/cell to 3.406 (overcharged) it added only .35Ah. That is what, 59.5 watts? That will get me backed out of the garage and started down the street, maybe 2 tenths of a mile, 2/10ths of 1% of the pack capacity. That's absolutely nothing on a 100 mile pack.


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## JRP3 (Mar 7, 2008)

I'd drop the charge voltage further, you're obviously still very close to over charging your cells.


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## EVfun (Mar 14, 2010)

ElectriCar said:


> Ok just finished a charge and made some notes. This should put some theories to rest.
> 
> I lowered the pack voltage to 169.4 last week giving me an average of 3.388VPC. *Some of you may have questioned/suggested I'm leaving a lot of power out of the batteries because they're not fully charged *so I adjusted the voltage up in increments then when the current went to nearly zero I noted the Ah put back into the pack.
> 
> ...


I'm a little confused, you wrote, "All told, from 3.88V/cell to 4.06 (overcharged) it added only .35Ah." In the first 2 paragraphs you indicated you went from 3.388 to 3.406. Is that a couple of typos in the 3rd paragraph?

I take from reading that you charge to a low voltage but let the current drop to nearly zero. How close to zero do you think you are getting? How long do you allow the charger to run after it hits the voltage limit (how long does the current taper)?

Your efforts give me some hope for charging without shunt regs. I bulk charge at 0.2C (12 amps.) I was charging with the regs to 3.65 vpc with a hold time at voltage limit of 10 minutes. When I went back to no regs I dropped the voltage to 3.50 vpc with a hold of 30 minutes. Both ways the cells where resting at 3.36 vpc the next morning. It looks like you are getting them closer to full with less voltage and less deviation between cells by hold the voltage down and adding time. Perhaps I'll try leaving my charger set to 133 volts (3.5 * 38 cells last year) when I initially charge this summer (3.41 * 39 cells this year) and just add some more hold time at the voltage set point.


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## ElectriCar (Jun 15, 2008)

EVfun said:


> I'm a little confused, you wrote, "All told, from 3.88V/cell to 4.06 (overcharged) it added only .35Ah." In the first 2 paragraphs you indicated you went from 3.388 to 3.406. Is that a couple of typos in the 3rd paragraph? *YES, CORRECTED*
> 
> I take from reading that you charge to a low voltage but let the current drop to nearly zero. How close to zero do you think you are getting? How long do you allow the charger to run after it hits the voltage limit (how long does the current taper)? *It tapers to 0.0 and will time out after a bit, not sure how long.
> 
> * Your efforts give me some hope for charging without shunt regs. I bulk charge at 0.2C (12 amps.) I was charging with the regs to 3.65 vpc with a hold time at voltage limit of 10 minutes. When I went back to no regs I dropped the voltage to 3.50 vpc with a hold of 30 minutes. Both ways the cells where resting at 3.36 vpc the next morning. It looks like you are getting them closer to full with less voltage and less deviation between cells by hold the voltage down and adding time. Perhaps I'll try leaving my charger set to 133 volts (3.5 * 38 cells last year) when I initially charge this summer (3.41 * 39 cells this year) and just add some more hold time at the voltage set point.


The manual for my batteries say charge to 3.6V then go into CV at that point, stopping charge after current drops to 0.5C or 10A. My charger won't do that as it just tapers the current to 0.0A and times out. Gizmo knows about the timer and probably how long the timer setting is.


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## GizmoEV (Nov 28, 2009)

ElectriCar said:


> The manual for my batteries say charge to 3.6V then go into CV at that point, stopping charge after current drops to 0.5C or 10A. My charger won't do that as it just tapers the current to 0.0A and times out. Gizmo knows about the timer and probably how long the timer setting is.


If it is the same as my NG1 and NG3 the "equalize phase" runs about 45 minutes to 2 hours, depending on how long the charge time was. I didn't sit there with a stop watch to get these times but they are reasonably close to what I have observed after the current tapered down below 2A or so. This is when the internal fans shut off so it is easy to notice if you are around when the pack is charging.


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## GizmoEV (Nov 28, 2009)

ElectriCar said:


> Ok just finished a charge and made some notes. This should put some theories to rest.
> 
> I lowered the pack voltage to 169.4 last week giving me an average of 3.388VPC. *Some of you may have questioned/suggested I'm leaving a lot of power out of the batteries because they're not fully charged *so I adjusted the voltage up in increments then when the current went to nearly zero I noted the Ah put back into the pack.
> 
> ...


I tried to point that out multiple times back in 2010 so it is nice to see someone else support my findings with actual pack data and not single cell data.


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## ElectriCar (Jun 15, 2008)

GizmoEV said:


> @ElectriCar: I'm trying to get an idea of what I'd be looking at for a 150mi S10 at 60mph.


Ha! I missed that. Well do get one of the newer ones that is more aerodynamic than a brick like my 91. At even 35 there is significant wind affecting the thing. I really like the 2003 model and I think the 04 was the last year they made it and then only in 4WD 4 door.

If I take it easy I can do under 300wh/mile on the CA, but I have to work at it! Over the last two years I averaged 365. This month I'm at 317.


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## 1-ev.com (Nov 4, 2010)

Sorry I've posted this in other threads, too, just to reach many as possible.

Do you guys know what happened to CALB USA http://calibpower.com/ ?

It looks like no page and no link from Chinese website http://en.calb.cn/ where it said "CALB USA" , but registration shows it valid until 2014...http://who.godaddy.com/whois.aspx?domain=calibpower.com&prog_id=GoDaddy


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## GizmoEV (Nov 28, 2009)

ElectriCar said:


> Ha! I missed that. Well do get one of the newer ones that is more aerodynamic than a brick like my 91. At even 35 there is significant wind affecting the thing. I really like the 2003 model and I think the 04 was the last year they made it and then only in 4WD 4 door.
> 
> If I take it easy I can do under 300wh/mile on the CA, but I have to work at it! Over the last two years I averaged 365. This month I'm at 317.


Thanks. It really helps to have real world data. I think I'll use 400Wh/mi for my calculations to give a little buffer. In addition to looking for a newer rig I think I'll also look for one with a manual transmission.

Thanks,


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## ElectriCar (Jun 15, 2008)

Well terrain of course affects the numbers. I live at the foothills of the Appalachian Mountains so it's fairly hilly here, even on the interstate. Your decision at 400 would be good as I believe where you are is hilly as well. I am planning to maybe underpen the thing to give me a little less drag underneath but I don't think that makes much difference.


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## ElectriCar (Jun 15, 2008)

Alright, how many of you guys are still active? I’ve converted it to a larger motor and automatic from manual. I know there are efficiencies but the convenience will be worth it. I think! 

Blew it up in 2012, order the new motor, a 500hp rated 700R4 and an adapter kit. Just now started wiring it back up. Hoping my 2011 Calb SE200 pack is still viable...


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## JRP3 (Mar 7, 2008)

I took a pretty big hit to efficiency going from manual to auto in my Fiero even without using a torque converter. Plus the gearing was a little too high. Hopefully yours will work out better.


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## ElectriCar (Jun 15, 2008)

Wow. I’m using a diesel torque converter with a very low stall speed. If everything still works after sitting for 6 years I’ll know before long. Have to put a shifter in it before I can roll! 

You still rolling in the Fiero?


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## dtbaker (Jan 5, 2008)

ElectriCar said:


> Wow. I’m using a diesel torque converter with a very low stall speed. If everything still works after sitting for 6 years I’ll know before long. Have to put a shifter in it before I can roll!
> 
> You still rolling in the Fiero?


The batteries *probably* are still ok if you completely disconnected from all loads. I would highly advise a cell-by-cell top balance by charging each cell to 3.65v with a revolectrix or something similar so that the pack is fully charged and re-balanced.

The EVwest guys have a pretty slick looking way to eliminate the torque converter and use a little pump to engage a Powerglide, but I don't have any more details than that.

my eMiata has been down for the last 3 months as the charger died and I'm due to replace the brushes anyway. I should have it back together in a week or two. I'm on the second transmission as hard starts in 3rd gear were too much for the stock tranny..... I'm contemplating *some* kind of upgrade, but not sure which way to go yet.


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## JRP3 (Mar 7, 2008)

ElectriCar said:


> You still rolling in the Fiero?


Yeah it's still going, range is down to about 25-30 miles now, hoping to move up to a Tesla Model 3 next year.


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## ElectriCar (Jun 15, 2008)

You still on LA or just a small LI pack? My LA pack of 24 232ah had a 30 mile range in warm temps.


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## ElectriCar (Jun 15, 2008)

dtbaker said:


> The batteries *probably* are still ok if you completely disconnected from all loads. I would highly advise a cell-by-cell top balance by charging each cell to 3.65v with a revolectrix or something similar so that the pack is fully charged and re-balanced.
> 
> The EVwest guys have a pretty slick looking way to eliminate the torque converter and use a little pump to engage a Powerglide, but I don't have any more details than that.
> 
> my eMiata has been down for the last 3 months as the charger died and I'm due to replace the brushes anyway. I should have it back together in a week or two. I'm on the second transmission as hard starts in 3rd gear were too much for the stock tranny..... I'm contemplating *some* kind of upgrade, but not sure which way to go yet.


yea I am going to smoke it over good maybe tomorrow. I have a 100 mile range or did but I dumped the Iota55 for an alternator and put the AC back in so with that on who knows how much range I’ll have. 

Idc so much about maximizing range anymore, just want to use it more for short trips and be comfortable!


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## JRP3 (Mar 7, 2008)

ElectriCar said:


> You still on LA or just a small LI pack? My LA pack of 24 232ah had a 30 mile range in warm temps.


Always been running Sky Energy, (CALB) 100's, 36 cells.


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## ElectriCar (Jun 15, 2008)

How many miles you have on them and how much capacity have you lost?


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## JRP3 (Mar 7, 2008)

About 25K miles, maybe 15-20% capacity loss. I've been hard on them, running the car till it stopped moving and cells below 2 volts under load at least 4 times, running at probably 2C average with peaks to 5.5C. I did have one cell die a few years ago, it was always an odd ball and initially I wasn't going to use it but decided to try it and see what would happen. I replaced it with a "new" old stock SE/CALB cell.


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## Frmf (7 mo ago)

ElectriCar said:


> Para quem não sabe, encomendei 51 células Calb SE200Ah em dezembro para o meu S10. Pago adiantado com um cheque direto para Calb para obter um preço com desconto. Esta atualização deve aumentar minha capacidade de viagem para cerca de 100 milhas dos atuais 30. Também economiza 719 libras, quase metade do peso do pacote de chumbo.
> 
> As baterias chegaram ontem. Hoje eu verifiquei as voltagens para ver o que eu tinha. Uma amostra de 12 células rendeu 9 a 3,265V, um par a 3,266V e um a 3,264V, todos dentro de 2/1000 de um volt. Muito incrível aí! Acho que está quase totalmente carregada para uma bateria Calb.
> 
> ...


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