# 200AH LiFePo4 Battery testing thread



## david85 (Nov 12, 2007)

My testing has started, and as promised, I will post the results as they come in.

I started by conducting the same test 3 times.

The tests consisted of running a Minn Kota 50 electric trolling motor at setting 3/5 (drawing 25 amps) in a barrel of water for 1 hour.

Heres how it stacked up for test 1:

Voltage measured with no load at full charge: 13.43V

Voltage under load after 

15 min: 13.16V

30 min: 13.14V

45 min: 13.13V

60 min 13.12V

Voltage after test:

5 min: 13.26V

10 min: 13.26V

15 min: 13.28V

Ambient temperature: 10 celsius

--------------Test 2:

15 min: 13.12V

30 min: 13.09V

45 min: 13.08V

60 min: 13.08V

Voltage after test:

5 min: 13.25V

10 min: 13.26V

15 min: 13.26V

Ambient temperature: 7-10 celsius (test started and 7 and ended at 10)

--------------Test 3:

15 min: 13.16V

30 min: 13.14V

45 min: 13.13V

60 min: 13.13V

Voltage after test:

5 min: 13.27V

10 min: 13.28V

15 min: 13.29V

Ambient temperature: 15 celsius (in direct sunlight, so battery was closter to 19)

I also turned the motor on and measured the voltage sag at each of the 5 settings:

no load: 13.43V

Setting 1 (10A): 13.38V

Setting 2 (15A): 13.36V

Setting 3 (25A): 13.3V

Setting 4 (30A): 13.27V

Setting 5 (62A): 13.07V (this setting is fun)

OK, pictures:

Shown are: Amp meter, Motor running at 25 Amps, Complete setup (battery, barrel, motor), Volt Meter, and charger.

The 4 lights on one end of the panel are showing voltage equilizing of the indivitual cells. The other two lights are RUN and CHARGE.
Run is green when ever the charger is working,
Charge starts off as red, then changes to yellow at 80% charge and finally to green when charge is complete (run light turns off when charge shows green).

I want to mention that these were VERY mild tests and don't really prove anything. Next tests will be with longer and longer run times until I can observe the rated energy storage of the battery. High draw tests will have to wait until I have a HD amp meter (in theory the battery can pump out 2000 amps.

Stay tuned........


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## rfengineers (Jun 2, 2008)

David,

Thanks for keeping us informed. I will be monitoring your progress.

Joe


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## david85 (Nov 12, 2007)

rfengineers said:


> David,
> 
> Thanks for keeping us informed. I will be monitoring your progress.
> 
> Joe


No problem. I just hope they live up to the claims because I want to be able to rip it up for longer drives with my EV I just don't see that as being reasonable in a lead sled.

OK, some unofficial updates.

Took our 18' boat to the lake today and for the first time ever, never started the engine. After having to repeatedly tighten down the clamps on the trolling motor (like I said, it is peppy), we were off for a lazy run around the lake. Ran the motor at full power for about 50 min till we got bored and decided to pack it in. Speed was actually pretty good considering the small size of the motor. (guessing 5 MPH)

I had the voltmeter and amp meter hooked up for the run.
Amps were right at 60 the whole time. Volts dropped to 12.78V initially when I first turned the motor on, but only fell to 12.77 by the end of the run. No noticeable loss in power at all, but relatively speaking, the test was very mild.

I consider this unofficial because I didn't take any notes during the test (going from memory), so take it with a grain of salt.

By the way, In case anyone is wondering how well the min kota motors work, I will give them a passing grade. They do make some noise at full power (more in reverse), but its still whisper quiet and is perfect for trolling. Can't beat the reliability or simplicity. Just hook up the two wires and turn it on.


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## david85 (Nov 12, 2007)

More official results.

Conditions before start of test:

outside temperature: 11.5 Celsius
Battery open circuit voltage: 13.82 volts

Test begins.........

Amp draw reads 28 Amps on setting 4, but could be 30, I need to verify the specs of the motor and see what others are seeing with this motor.

Closed circuit voltage:

1:00 = 13.33 volts <<< I measured a voltage after 1 min to show initial voltage drop
15.00 = 13.04 V
30:00 = 13.03 V
45:00 = 13.02 V
60:00 = 13.02 V <<< I took measurements every 15 minutes only for the first hour to act as a control for previous tests, then every 30 minutes for the remaining 4 hours because I've got other things to do!
1:30:00 = 13.01 V
2:00:00 = 12.99 V
2:30:00 = 12.97 V
3:00:00 = 12.93 V
3:45:00 = 12.92 V <<< sorry, I was late checking the voltage.....(other things....)
4:00:00 = 12.91 V <<< ambient temperature 12.2
4:30:00 = 12.90 V
5:00:00 = 12.88 V

SHUTDOWN.......

Open circuit voltage after load:
5:05:00 = 13.08 V
5:10:00 = 13.10 V
5:15:00 = 13.10 V <<< ambient temperature 11.3

End of test.....

The battery did well and is on charge right now for the next test. Next step will be to repeat the test to verify the results.

If my amp readings are in fact 30 amps, then it means I have reached 75% of the battery capacity with this test. 30 amps x 5 hours = 150 AH.

The battery is rated at 200 AH. So far so good, but I'm just getting started............................................stay tuned


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## mark1030 (Jul 28, 2008)

david85 said:


> More official results.
> 
> Conditions before start of test:
> 
> ...


The open circuit voltage before the test is less than it is at 1 minute operating. Is that right?


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## david85 (Nov 12, 2007)

mark1030 said:


> The open circuit voltage before the test is less than it is at 1 minute operating. Is that right?


No its not, thanks for catching that. I looked at my notes again and it was in fact *13*.82 not* 12*.82.

I've made the correction to the post.


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## TX_Dj (Jul 25, 2008)

David,

What is the "resting voltage" of the battery 24 hours after shut down, with no charging? How much does it recover? This may be a better measure of the SOC for the cells after the tests are concluded.


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## david85 (Nov 12, 2007)

TX_Dj said:


> David,
> 
> What is the "resting voltage" of the battery 24 hours after shut down, with no charging? How much does it recover? This may be a better measure of the SOC for the cells after the tests are concluded.


Not a bad idea. I'll do that after I repeat the last recent test.


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## dimitri (May 16, 2008)

Dave,

do you have any plans to test this batt at 1c to 3c load? That would be most beneficial for EV application. I would love to know how many Ah it can deliver at 1c continuous and bursts of 2c or 3c. Its nice to know that it holds up well at 0.3c, but it doesn't tell us how it will hold up in real EV load conditions due to Puekert's law. Are these rated for 1c continuous or more?

Also, I apologize if I missed it somewhere, but can you publish weight and dimensions of the individual battery? My understanding is that prismatic LiFePo batteries have relatively low energy density, which makes complete pack quite bulky and heavy, although still better than lead-acid.

Thanks for publishing your test results, looks great! I keep a close eye on these since it will be my next pack once my current pack dies...


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## david85 (Nov 12, 2007)

I'll be working up to that, dimitri. For now I am equipped to test long low C discharge to verify the (claimed) rated energy storage of the battery, so thats what I'm working on. The energy density is on average around 100wh/kg for most Lifepo batteries that are made in china like the one I am testing. Having said that, I do not know the exact weight of these ones yet. But they feel comparable to a 600 CCA starting battery.

Keep the comments comming guys! If you have any suggestions to make the tests better, I'll do what I can to incorporate your ideas. I'm not exactly a 'man of science', after all.


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## david85 (Nov 12, 2007)

More results:

outside temperature: 9 Celsius
Battery open circuit voltage: 13.33 volts

Test begins....

1:00 = 13.11 V
15:00 = 13.05 V
30:00 = 13.04 V
45:00 = 13.03 V
60:00 = 13.03 V
1:30:00 = 13.02 V
2:00:00 = 13.00 V
2:30:00 = 12.96 V
3:00:00 = 12.94 V
3:30:00 = 12.92 V
4:00:00 = 12.91 V <<< outside temperature 11.5
4:30:00 = 12.89 V
5:00:00 = 12.88 V

Shut down....

5:05:00 = 13.10 V
5:10:00 = 13.11 V
5:15:00 = 13.12 V <<< outside temperature 13

The battery is not on charge and I'll take another reading tomorrow evening to see what the voltage is. Before comming in, it had crept up to 13.14 V, so looks like you had a good idea, TX_Dj.

I really should apologize for the quality of these pictures as they are all taken off my cell phone so far. Better something than nothing, I figured. Note that I have moved to an indoor location since this will be an ongoing thing for the next little while. I used the larger tank hoping to be able to do a full power test, but it still has a dendancy to splash out, hence the plywood on top of the tank.


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## RKM (Jun 9, 2008)

David,

Have you been monitoring each of the four individual cells wrt to max charge and discharge voltage? Do you have any means to keep them in balance once you put greater load on the battery?

Your initial testing is good to see, but as dimitri points out, the really interesting data will be testing under higher C loads.

I'm really, really interested in these batteries. Are they available in a 160 Ah size? I'd like the 200 Ah but may have to compromise with a smaller pack. You had said these are rated 1 C continuous with a max up to 5 C?

If your tests go well for these cells, I'm definitely interested in joining you on a purchase. Do you suppose the "global economic slowdown" will pressure prices lower?

Thanks again for doing the testing! Much appreciated!

Rob


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## david85 (Nov 12, 2007)

RKM said:


> David,
> 
> Have you been monitoring each of the four individual cells wrt to max charge and discharge voltage? Do you have any means to keep them in balance once you put greater load on the battery?
> 
> ...


Hi Rob

The charger has a cell ballancer built into it and I describe some of that in the first post. What it does is charge at max current up to a point, then at near the end of the charge cycle backs off and starts to equilize the individual cells. There is no means of ballancing during the discharge cycle. I haven't checked recently, but there seems to be roughly a 0.11V difference between the highest and lowest module.

Tony (sales rep) said they tried using a BMS module right on the individual cells but they kept burning up, so they opted for a ballancer feature on the charger instead. Considering the claimed 1000amp peak rating of these cells, I can understand the reasoning.

I believe that do make a 160 AH cell as well, I can ask to make sure. So far, they have been very helpful. Since these are only rated for 1C continuous rating, I opted for the 200 AH. I think thundersky claims 2C constant, and very similar cycle life performance.

The major internal difference between these cells and TS is that they are made up of several internal soft packs instead of a single large prismatic cell. The advantage is a built in redundancy because of the parallel connection. I single cell that fails in these cells will not disable the car.

Global slowdown might help keep prices in check, but if the canadian dollar falls any more, that won't do us much good as it would kill our buying power. I'm not sure how the US dollar and the chinese currency are doing at the moment. Oil can't stay cheap forever though.

For the 5C test, I think I have a way of testing that. The 1C test I still have to figure out, because I don't have anything thats 12V that only draws 200 amps.


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## RKM (Jun 9, 2008)

David,

I'd missed the bit about the BMS in the charger.

I just checked on the exchange rate. The CAD has softened about 13% against both the CNY and USD since August 1, 2008. You're right, as oil and minerals go, so goes our dollar. Oil won't stay low for long!

A 144 V X 160 Ah pack should push a 2600 pound car down the road at 100 kph (at a 1 C rate)? On this assumption, I can get away with a 1 C continuous discharge.

Has Tony given any indication of a discount rate for a larger order? 

Rob


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## david85 (Nov 12, 2007)

No, he's a tough sales rep, LOL. He would not even confirm that the price I paid was possible for any potential order later on. But he did give a 25% discount after much haggling, so it would seem that there is no fixed pricing rate. I suspect I was not given the best possible price, but it was fairly close.

As a general rule, the going rate seems to be ~$0.50/ watt hour of capacity (for the cells only, as in no charger, or BMS). Mine came to $0.47 / watt hour. He gave me that price after I mentioned that I was quoted $0.45 earlier from a different supplier (still have records of that price quote). In other words, don't pay more than $0.50 /wh unless its retail.

Its really hard to say how the latest slowdown will affect the price of batteries, but generally the demand drops with the price of oil, so at the very least, prices are not likely to go up in the near term. Add to that the fact that it seems that this is very competitive and production is on the rise in china, and lets just say theres no need to rush with a group buy.

144V and 160 amps works out to roughly 30 Hp assuming no loss. I really don't have any official specs on what it takes to move a 2-3000 lb car down the road, but I think 30 Hp is enough once you are cruising. Most cheaper DC brushed motors are not rated for more than 30Hp constant, so I would guess that it is enough since these motors are being used in cars of that size range.

And for the update for the battery SOC after resting for a day......

*Measured voltage after 24 hours was 13.09V and outside temp was 9 degrees.*

It seemed to be more affected by ambient temperature than resting time. Voltage peaked at 13.14V about 2 hours of resting. Yesterday's high was 13 degrees, so I think thats why the voltage has since come back down a little.

Again, since there is no 'paper trail' with these observations take it for what its worth (estimates).


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## bblocher (Jul 30, 2008)

Pretty cool. Thanks for taking the time to do this. I was debating doing something like this but for cycle life. After realizing the time it would take to prove or disprove their claims I realized I didn't have that much time spare and we'll just have to see how well they hold up over time. 

Keep us posted.


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## dimitri (May 16, 2008)

David,

I'm trying to understand how charger is balancing each cell. Does it mean that charger has a separate circuit coming out of it for each cell, in addition to main power circuit that charges whole pack? Assuming your charger is for 12V pack of 4 cells that seems simple enough, but when we apply this to 144V pack of 45 cells, what will the charger connection be like? 45 wires coming out of it? Seems excessive and complicated... Are there any other options? I read online that some people adapt same Zivan NG3 chargers used for lead acid, by changing the program chip to lithium charging curves. I wonder how they manage balancing then? The whole BMS thing is still a mystery to me, seems there are many approaches to it, need to find the best for EV application, considering number of cells and high currents involved.


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## bblocher (Jul 30, 2008)

dimitri said:


> David,
> 
> I'm trying to understand how charger is balancing each cell. Does it mean that charger has a separate circuit coming out of it for each cell, in addition to main power circuit that charges whole pack? Assuming your charger is for 12V pack of 4 cells that seems simple enough, but when we apply this to 144V pack of 45 cells, what will the charger connection be like? 45 wires coming out of it? Seems excessive and complicated... Are there any other options?


You are correct. Either the charger must be capable of charging each cell seperately or you need cell balancers on the cells. I seriously doubt you'll find a charger that supports the number of cells we'll need.

I know Elite Power Solutions has BMS systems for up to 100 cell packs. If the cell balancers are burning up, they were designed wrong. Perhaps they were trying to balance too quickly instead of doing it over longer periods of time.


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## Zemmo (Sep 13, 2007)

Just to give you a working example of amp draws. My traction pack is 120 v (lead acid) and to drive 45 MPH typically is about a 60 to 70 amp draw. At 60 mph I typically draw 115 to 130 amps. My acceleration is typically at 150 amps say over 30 seconds until at speeds. If I get into heavier traffic, I don't want to slow people down too much while accelerating, I will pull around 200 amps. If I just absolutely have to git up and go, I can pull 250 amps but would drop it down to 200 amps shortly. The absolute max I have ever pulled from my pack is 420 amps (for a very short time). All of these reading are from my shunt on the battery side, not the motor side. My car isn't light either, about 3400 lbs (the pack is about 1320 lbs of it).


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## david85 (Nov 12, 2007)

Zemmo said:


> Just to give you a working example of amp draws. My traction pack is 120 v (lead acid) and to drive 45 MPH typically is about a 60 to 70 amp draw. At 60 mph I typically draw 115 to 130 amps. My acceleration is typically at 150 amps say over 30 seconds until at speeds. If I get into heavier traffic, I don't want to slow people down too much while accelerating, I will pull around 200 amps. If I just absolutely have to git up and go, I can pull 250 amps but would drop it down to 200 amps shortly. The absolute max I have ever pulled from my pack is 420 amps (for a very short time). All of these reading are from my shunt on the battery side, not the motor side. My car isn't light either, about 3400 lbs (the pack is about 1320 lbs of it).


Great post, Zemmo (nice car too) that gives us a good baseline to compare against. I'm supprised it takes so little amps to keep your car going. 70 amps and 120 Volts is a little more than 10 Hp. I think I will be able to perform a 60 amp test with this setup, so that could be the basis for some early projections for vehicle range. Couldn't before because the water kept splashing out of the tank heehee (hence the plywood on top).

About the charger, yes there is a seperate connection to each cell that goes to the charger. The number of wires is number of cells + 1, so in this case, 4 cells means 5 wires. There is a seperate quick connector. I'll take a picture of it next chance I get. I can also ask now many cells the charging system can support for a fullsize traction pack. The ballance period does take a long time with this charger. Haven't taken any measurements of the time yet, but it seems to take at least an hour to ballance at the end.

I just got a reply to a question I sent them about the safe low voltage of this battery. She tells me that 9.2 V is the lower safe limit for this battery. That works out to 2.3 V per cell. I've only been to 12.88 (or 3.22 V per cell) so far (under load). This will take a while I think.....


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## Zemmo (Sep 13, 2007)

Thanks for the comments about my car. I do really like it. I got videos of a ride long on my YouTube site. You can see what the amps and volts do when driving along.

I think balancing the batteries in an hour isn't that long at all. A typical EV sits plugged in over night, so there is plenty of time to balance out the pack.

Also this charger seems ideal for charging Lithium batteries. For a 144 volt pack, instead of one large charger, you can have 12 smaller one. So each 4 cells has its own which does't seem too bad to wire up (when you look at them as 12 separate chargers). There is quite a few builds out there that do this because it is typically cheaper to buy 12 smaller chargers than 1 large one.


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## david85 (Nov 12, 2007)

I think this charger can handle up to 16 cells. If you look at the photo in the 1st post of this thread, you can see that only 4 out of 16 LED slots are lit up (besides the two on the other end). You can't see it in the photo, but there are slots in the internal PC board for more LEDs to be fitted when the charger is assembled. That could cut down on the number of chargers needed considerably, but there still may be a charger that can handle the number of cells needed for a highway EV. The charger itself was $130 USD for my sample order.

5 star rating? when did that happen?


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## david85 (Nov 12, 2007)

Was in the shop for a minute so I took one last reading before putting it on charge again.

13.11 V

outsite temperature 8.5

I'll be a little busy with work over the next few days, but i'll try and carry on with the testing and keep you all up to date.


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## bfloyd4445 (Oct 16, 2008)

r u thinking of using these batteries for a boat?


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## david85 (Nov 12, 2007)

Hi bfloyd, glad to have you over here. In case anyone is wondering, I know this guy from another forum. He had a chance to drive the EV1 (and other OEM EVs) for a while, so feel free to fill up his PM inbox with questions heehee

I already used it in our little 18 footer for about a 1 hour run and full power and it was going fine but we got bored so came back home, have to bring some snacks next time. There was no noticeable loss in power when I finally shut it off. They should work well for a boat or any other EV for that matter. It also looks like it will be a nice emergency backup power for the ol' evenrude V4 engine. 1 Hour run time is not bad at all, but I expect at least 3 times that if the ratings are accurate(must test to confirm).

The issue I am trying to address with this testing is to see if the chinese made battery can be trusted. Earlier examples of lithium batteries from china didn't do so well.

I have a feeling that things have changed since then, but considering the cost of such an investment, you can't be too careful. Since others are interested in the new technology as well, I figured I'd share the info as it comes in. I take my hat off to these chinese companies anyway for offering products like this when domestic suppliers often do not even return our inquiries. Quite frustrating.


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## bfloyd4445 (Oct 16, 2008)

david85 said:


> Hi bfloyd, glad to have you over here. In case anyone is wondering, I know this guy from another forum. He had a chance to drive the EV1 (and other OEM EVs) for a while, so feel free to fill up his PM inbox with questions heehee
> 
> I already used it in our little 18 footer for about a 1 hour run and full power and it was going fine but we got bored so came back home, have to bring some snacks next time. There was no noticeable loss in power when I finally shut it off. They should work well for a boat or any other EV for that matter. It also looks like it will be a nice emergency backup power for the ol' evenrude V4 engine. 1 Hour run time is not bad at all, but I expect at least 3 times that if the ratings are accurate(must test to confirm).
> 
> ...


one of my colleges is a phd from China. She recently had a baby then because of family presure sent her baby to China for six months with her parents to meet them. When i heard about the melamine in chinese baby food i became concerned for the safety of her child and mentioned it to her. She said Oh no, I don't buy anything, especially food, of chinese origin unless I has to and my baby went with enough US baby food to last untill his return. 
So there you have it, even intellegent Chinese don't buy Chinese. Do you buy Chinese, cept for suspect batteries? I don't, havent for years if i can avoid it.


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## david85 (Nov 12, 2007)

As a general rule I try and buy local product (especially food), but in the case of more advanced batteries, domestic companies like a123 systems, electrovaya, altair and ovonics (who are all world pioneers, by the way) either will not or are not allowed to deal with private customers. We have been left with no choice other than using lead acid. Not all chinese product is junk, but as far as food safety in china goes, there are some problems there and the world knows it. I hope they can sort it out.

What sparked my interest in chinese batteries was a video of "impact testing" of a lithium polymer cell which was basically being mashed, mangled and cut into pieces in a sheet metal sheering machine. Not even any smoke was visible and it continued to produce voltage (with some fluctuation) until the end of the test.

This in itself is not proof enough of course, but I did start looking more and more into potential suppliers in china and other countries overseas since local companies were not an option. China is now the worlds largest supplier of lithium batteries followed by japan. South Korea is also a major player. I'm still not completely convinced, but I am doing what I can to verify the performance claims and I know others are as well.


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## bfloyd4445 (Oct 16, 2008)

For me China and japan, some other countries have been on my, do not but products from, list, for many many years for reasons other than poor product. I support countries that have acceptable human rights and environmental standards and china has been a big time human rights violator forever. If our goverment would make a law that said any product sold in the USA must be manufacturered to the same environmental and human rights standards as if it were made in the USA it would level the playing field for American companies and also encourage other countries to clean up there act if they wish to tap the US market.

Good luck with your experiment


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## david85 (Nov 12, 2007)

I see your point bfloyd4445, but I feel things are getting better and china is opening up partially from international pressure, but also because of the economic development that has happened in the last 20 years thanks to closer economic ties with the west. I don't want to challenge you on your opintion though, its your right to have that opinion and I respect you for it. Our views are not nearly as far apart as some others on the forum and we all still get along just fine. I'm still glad you are here and I hope you stick around

OK more results:

Voltage before test: 13.60V
outside temperature: 9.5 celsius
Powersetting: 5 (62+amps)

Test starts:

1:00 - 12.79V
5:00 - 12.69V
10:00 - 12.69V
15:00 - 12.69V
30:00 - 12.68V <<< amp reading now shows 61 amps

Problem found......

There was a loose connection between two of the cells, instead of scrubbing the test I tightened the terminal bolt and carried on. You can see the voltage increace after I tightened the bolt.

36:00 - 12.76V
45:00 - 12.72V
60:00 - 12.70V
1:15:00 - 12.68V
1:30:00 - 12.68V
2:00:00 - 12.63V
2:30:00 - 12.55V
3:00:00 - 12.38V <<< outside temperature 10.5 celsuis
3:15:00 - 12.20V
3:20:00 - 12.07V <<< amp gauge now shows 60 amps
3:25:00 - 11.92V
3:30:00 - 11.72V
3:35:00 - 11.44V <<< I've been told by my contact that the lowest safe voltage is 9.2V

Shut down:

1:00 - 12.20V
5:00 - 12.48V
10:00 - 12.59V
15:00 - 12.63V

Measured the the battery temperature to be 14.5. I'll let it sit overnight and measure the voltage again.

I was hoping to see 3 hours run time, but over 3.5 hours was a nice supprise, even more so considering fairly cool outside temperatures.
60amps x 3.5 hours = 210 amp hours, the cells are rated for 200 AH.
210 x 12 volts = 2.52 kwh of energy
Don't start celebrating just yet, I still need to figure out a way to increase the amps with the test, ideally to 200 amps. There is also the high C test to conduct but I don't have the gadgets needed for that yet. I also need to repeat this test to verify the results. But at least we now have SOME numbers for a 60 amp test.

I could also tell that this was pushing the motor to it's limit. Much of the amperage drop seems to be from the wires for the motor heating up. The speed controler was also pretty warm too (50 degrees actually). Once the wires heated up as far as they were going to go, the amperage drop stopped, so thats why I draw that conclusion (hotter wires create more resistance). The battery didn't blink, the only change was an increace in temperature above ambient by about 5 degrees.

I have some pictures from this test, but my phone is bull****ing me at the moment (again). I'll post them later on if I can. I hate this thing.....


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## david85 (Nov 12, 2007)

OK time for pictures:

First you see the trolling motor at full power in the big plastic tub. The pluwood is there to keep the water from slpashing out as it sloshes around in there. Next you see two pictures of the amp meter showing the difference between the cold start and the drop that happened later on after the wires warmed up a little. Then there is the voltage reading that I took when I noticed that one of the battery connectors was warm to the tourch.

Oh, and there was a thunder shower right around the 3.5 hour mark and it hailed briefly. As you can see, its fall up here.


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## david85 (Nov 12, 2007)

dimitri said:


> David,
> 
> I'm trying to understand how charger is balancing each cell. Does it mean that charger has a separate circuit coming out of it for each cell, in addition to main power circuit that charges whole pack? Assuming your charger is for 12V pack of 4 cells that seems simple enough, but when we apply this to 144V pack of 45 cells, what will the charger connection be like? 45 wires coming out of it? Seems excessive and complicated... Are there any other options? I read online that some people adapt same Zivan NG3 chargers used for lead acid, by changing the program chip to lithium charging curves. I wonder how they manage balancing then? The whole BMS thing is still a mystery to me, seems there are many approaches to it, need to find the best for EV application, considering number of cells and high currents involved.


I can ask what the limit for the charger is, but it can definitely handle more than just 4 cells if set up for more at the factory. Heres how the ballancer connector looks/works:

Its got N + 1 wires in it, so for this battery N = 4, so 4 + 1 = 5 wires in total.
The connector appears to be a cast metal pot metal of some sort and has keyways in it to prevent being connected improperly. Once lined up and pressed in, there is a thread on sleeve that holds it securely connected. Then the charger does everything else automatically. The 4 red lights are the ballancing circuits active, and come on only near the end of the recharge cycle.


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## bfloyd4445 (Oct 16, 2008)

david85 said:


> I see your point bfloyd4445, but I feel things are getting better and china is opening up partially from international pressure, but also because of the economic development that has happened in the last 20 years thanks to closer economic ties with the west. I don't want to challenge you on your opintion though, its your right to have that opinion and I respect you for it. Our views are not nearly as far apart as some others on the forum and we all still get along just fine. I'm still glad you are here and I hope you stick around
> 
> Hey, discussion is a learning tool and that is what we do. We voice opinion then with the new information can adjust our operateing agenda if necessary.
> You see i often work with people, mostly engineers, scientists, from around the world so are exposed to facts direct from the horses mouth, so to speak. I hear exactly how things are in those countries not filtered by the media or goverment censorship. And if what my colleges from China and others that visit China often say is true the situation has not improved for the worker but gotten worse. Were at one time the worker led a simple life based upon agriculture living close to the land he/she now lives in crowded polluted urban city environments in slave shops very similiar to what we had here during the industrial revolution and before the labor movement. No David, little has improved in china for the worker only for the Chinese rich. Sad, the Chinese people are a great people and it hurts me to see chinese items for sale in stores that i know were produced by children that labor all day in chinese factories. Maybe if there were less demand for these products fewer of these children would have to endure this torture? And the reason i would like to see a law that would require any product sold in the USA be manufacturered to the same human rights and environmental standards as if it were manufactured in the USA. This would put presure upon foreign goverments to change their practices cleaning up their act making a better world for workers every where. Wouldn't that be nice?


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## Zemmo (Sep 13, 2007)

Thats some great pictures of the charger. I like the idea of the charger balancing out the cells. Have you ever checked the cells when the charger is in its balancing stage? So see what it is getting each cell up to? Also at resting after charging.

You by chance wouldn't happen to have a 2nd trolling motor handy do you? You could then double the amps really easily that way. Maybe you could borrow one for the tests? Just trying to think how you can get a higher amp load easily.

Thanks for all of the work and time you have put into testing, keep it up!


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## david85 (Nov 12, 2007)

Zemmo said:


> Thats some great pictures of the charger. I like the idea of the charger balancing out the cells. Have you ever checked the cells when the charger is in its balancing stage? So see what it is getting each cell up to? Also at resting after charging.
> 
> You by chance wouldn't happen to have a 2nd trolling motor handy do you? You could then double the amps really easily that way. Maybe you could borrow one for the tests? Just trying to think how you can get a higher amp load easily.
> 
> Thanks for all of the work and time you have put into testing, keep it up!


I don't know anyone that has another one and this is already the biggest 12V one I could find. A second motor would probably also cause cavatation in the water, even this one was pulling a wirlpool down to the prop once in a while. I'll have to think of something though.

I haven't taken much measurements of the ballancer at work, but did notice a variation of the voltage from once cell to another of up to ~0.15V Haven't checked it recently.

Took a reading off the pack a few minutes ago, the voltage was 12.8V, outside temperature was 4 drgrees this morning.....


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## ragee (May 25, 2008)

David,

This is excellent information. In reading this post I am learning a lot about LiFePo4. I too am running LA batts and hope for my next set to be these batteries. Keep up the good work it is greatly appreciated.

R Agee


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## bfloyd4445 (Oct 16, 2008)

david85 said:


> I don't know anyone that has another one and this is already the biggest 12V one I could find. A second motor would probably also cause cavatation in the water, even this one was pulling a wirlpool down to the prop once in a while. I'll have to think of something though.
> 
> I haven't taken much measurements of the ballancer at work, but did notice a variation of the voltage from once cell to another of up to ~0.15V Haven't checked it recently.
> 
> Took a reading off the pack a few minutes ago, the voltage was 12.8V, outside temperature was 4 drgrees this morning.....


The battery pack will drain twice as fast if you double the electrical load. However, there are lots of varibles when useing a trolling motor because of fluctuating load conditions and the ability of the propellers to transfer energy to the water.
Another way is to measure the actual amp draw under full load timed for say 15 seconds then use that and the battery voltage to calculate the resistance of the motor. With this information and the storage capacity of the battery it is simple to calculate how long the battery will last at twice the draw as long as you don't exceed the battery packs design limitations. But, that isn't a problem because once you know the resistance of the motor you can simply make up a dummy load with a resistor equal to twice the motors resistance and then bench test your battery pack for an exact time.


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## david85 (Nov 12, 2007)

Not sure how to make a dummy resistor (safely), I'm open to any ideas though.

More results:

Voltage before test: 13.37V
Outside temperature: 9.5
Setting : 60 amps

1:00 - 12.82 V <<<62 Amps
5:00 - 12.78 V <<<61 Amps
10:00 - 12.77 V
15:00 - 12.75 V
30:00 - 12.73 V
45:00 - 12.68 V
60:00 - 12.66 V
1:30:00 - 12.62 V
2:00:00 - 12.50 V
2:30:00 - 11.95 V <<<60 Amps
2:45:00 - 11.08 V <<< 59 Amps
2:50:00 - 10.59 V <<<58 Amps
2:53:00 - 10.30 V <<< 50 Amps....test terminated (outside temp 10.5)

As you can see, I didn't even make it to the 3 hour mark. I'm at a loss to explain this result. All I can do is repeat the test again and see what happens.

The battery has been stored outside and overnight temperatures have been getting lower. Every test so far has been with the battery being stored for a minimum of 24 hours before running the test, this most recent test was stored for longer. Is that the cause for a different result? I can't say for sure, but I hope to find out. Work is also keeping me busy at the moment as a few last minute customers decided that they all need work done yesterday even though winter is supposed to be the slow part of the year......Tomorrow I'll be out of town and the weekend looks like its pretty much booked.

As for the charger limitation, there doesn't seem to be one. Emily tells me that all they need to know is the desired voltage of the pack and they will do the rest. She asked me if we are interested in making a trial order.......I still feel its a little too soon for that, but unless something drastic happens, I'm leaning toward going with these batteries. I wish this testing wasn't taking so long.


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## gmijackso (Sep 30, 2008)

david85 said:


> Not sure how to make a dummy resistor (safely), I'm open to any ideas though.


There are a couple of easy ways, one is to use the heating elements from an old electric stove/oven. The other is to parallel a bunch of light bulbs. In either case I would try to blow a fan across them to ensure they don't get too hot and to try to keep everything at as constant a resistance as possible. 

I would probably try to use an old oven element personally. I've only ever done this with high power things with a fairly high voltage. Not sure how it would work for low voltage, but an oven element is basically just a resistor, the trick is getting it with a low enough resistance to draw enough current at a low voltage.

However, a Carbon Pile load tester is probably your best option. One can be had from harbor freight for $50, not sure of the duty cycle, but I would figure the 500A load tester can probably run at 100A for a reasonable amount of time, especially if you cool it with a fan to be safe.

My .02


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## genawin (Oct 1, 2008)

i ordered a 24 cell 100ah pack direct from this factory back in june and they are currently being shipped ,so i have been reading this thread with great interest and fingers crossed, Could i suggest as a test load using an inverter then you could put all this power to good use or charge some other batteries and then use them to recharge the test batteries. i just can't bear to see energy going to waste !


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## Bottomfeeder (Jun 13, 2008)

I just found this thread, and am duly impressed. I am already day-dreaming about upgrading my lead acids while my car isn't done yet. Great work with the simple tests. I'll probably upgrade to these batteries or similar when my pack fails. And it's heartening to see people testing them systematically. It seems like you need to draw a few more amps to really simulate EV usage. But, when you get to that point it won't take 5 hours to drain the pack!

Great work!


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## jorhyne (Aug 20, 2008)

Sorry if I missed it guys but david85 where did you buys these batteries? I am working on a motorcycle conversion and would be interested in a smaller pack perhaps...


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## david85 (Nov 12, 2007)

genawin said:


> i ordered a 24 cell 100ah pack direct from this factory back in june and they are currently being shipped ,so i have been reading this thread with great interest and fingers crossed, Could i suggest as a test load using an inverter then you could put all this power to good use or charge some other batteries and then use them to recharge the test batteries. i just can't bear to see energy going to waste !


LOL, welcome to the forum genawin!

Please keep us posted on whatever you find out with your batteries. As it stands right now, you are the one who is furthest ahead on this forum with these batteries. You ordered a full size battery pack, I only ordered a sample as did at least one other member.

Might get a carbon pile tester eventually. I think I have a farily close supplier if it comes to that.

I still want to urge some caution here though. These tests have only scraped the surface of what these batteries are supposed to be capable of. Higher C discharge tests are comming....

This is the company website:
http://www.chinabatterycenter.com/


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## bfloyd4445 (Oct 16, 2008)

gmijackso said:


> There are a couple of easy ways, one is to use the heating elements from an old electric stove/oven. The other is to parallel a bunch of light bulbs. In either case I would try to blow a fan across them to ensure they don't get too hot and to try to keep everything at as constant a resistance as possible.
> 
> I would probably try to use an old oven element personally. I've only ever done this with high power things with a fairly high voltage. Not sure how it would work for low voltage, but an oven element is basically just a resistor, the trick is getting it with a low enough resistance to draw enough current at a low voltage.
> 
> ...


you must calculate the resistance needed to have the amp draw you wish first then add enough elements in series to equal the total resistance needed. If you don't you could over draw from the batteries which can cause certain types of batteries to explode. Since we are useing DC you can use ohms law for calculations. E=IxR. E is voltage, I is current in amps, R is resistance in Ohm's. to solve for R you transpose the formula so R= E/I. Got it? With heating elements you don't have to worry about wattage but if you use a resistor it must have a high enough wattage to handle the curent without buring up. here is a handy calculator http://ourworld.compuserve.com/homepages/Bill_Bowden/ohmslaw.htm

opps, I believe the calculator above is for Ac circuits and usesP= I squared R, for Dc P=IxE. P= watts, I = current in amps and E is voltage DC


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## gmijackso (Sep 30, 2008)

My only concern for difficulty was the resistance of the heating elements. Since he is working with 12V and looking for hundreds of amps in the end, he needs something with very small fractional resistance (as in fractions of an ohm). I've only ever used the heating elements to simulate a 50 ohm load, which isn't very difficult. Getting them to simulate a motor drawing 200 amps means 0.06 ohms, not sure that's even possible with heating elements.


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## Wirecutter (Jul 26, 2007)

David -
I'd like to add another "thanks" to the pile. Thanks for doing this testing and posting results.

Early in my career, collecting battery test data was part of my job. I was running tests on alkaline, lithium thionyl chloride, lithium sulphur dioxide, and even mercury cells. Some tests ran two years, most ran a year. I was young then, and while I found it boring, I dutifully collected and reported my data. At the end, getting results was always a big boost.

It may not be sexy, but getting data is very useful, and I think we all appreciate your sharing it.

-Mark


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## bfloyd4445 (Oct 16, 2008)

gmijackso said:


> My only concern for difficulty was the resistance of the heating elements. Since he is working with 12V and looking for hundreds of amps in the end, he needs something with very small fractional resistance (as in fractions of an ohm). I've only ever used the heating elements to simulate a 50 ohm load, which isn't very difficult. Getting them to simulate a motor drawing 200 amps means 0.06 ohms, not sure that's even possible with heating elements.


Sure is. for resistors in parrelle in a dc circuit the sum of the total resistance is 1/ 1/r1 +1/r2+ 1/r3+ etc. So you can see that the resistance quickly goes down. But if that is the resistance you need you can use aluminum wire of the correct lenght to give that resistance. Even copper wire will work. But why do you need to go that high on amps anyway? Would be kind of an interesting experiment and its always neat to watch your wire load turn red, yellow, white and melt!


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## david85 (Nov 12, 2007)

bfloyd4445 said:


> But why do you need to go that high on amps anyway? Would be kind of an interesting experiment and its always neat to watch your wire load turn red, yellow, white and melt!


That does sound like fun!
The point of the tests are to see if these batteries can discharge enough current (as claimed) to properly power an electric car up to speed and over hills.

There was an earlier group purchace that saw lots of EV enthusiests put their money down for thundersy batteries that turned out to have too much internal resistance to properly even allow a car to hold speed let alone have acceptable acceleration. The reserve capacity was better than lead acid, but the the current rating was just not good enough. This piece of history is why I'm going through so much trouble now to see what these batteries can _really_ do before spending on a whole pack.

So far I've tested as far as 60 amps. Thats enough for a lighter car to hold speed at below highway speeds. Acceleration would not be satisfactory though. Most controllers for highway capable vehicles are rated for 400 amps or more for instant rating.

I'm planning around a 144V battery and 200 amps peak would give satisfactory performance for cruising. 28.8 kw (assuming 100% efficiency) or 144kw at 1000 amps for acceleration (if I can ever get a motor controller big enough now that the zilla has been discontinued). The saturn that I have is rated at 100Hp stock....

These batteries are supposed to be good for 200 amps constant or 1000 peak. So far I have only been able to verify the reserve capacity but not the current rating.

*Now for a few few more general updates.......*

I scored a donor car on sunday. I'll start a thread tomorrow on that.

More info on the different results for the 60 amps tests. I had the battery sitting overnight again for a few days and put it on charge again without placing any load while it was sitting. The charger gave it a full 25 amps for over an our before starting to back off and eventually go into ballance mode. Again, there are no recorded results for this, because rework in the shop that I had to finish and was out the door before I could see the charge finish, but this is enough for me to plan the next test.

I will make sure the battery has a fresh charge this time instead of letting it sit overnight. I'll give it some 5 minutes of 60 amp draw, recharge and then start another long run 60 amps test. I hope this is the reason why I could not make it to 3.5 hours the second time (would rather have 3.5 instead of 2.75 hours as the official result)

I also noticed the cells are ballancing better at the end of the charge. There is a much smaller difference between them now. Well under 0.1 V.

Please bear with me guys, I'm going as fast as I can


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## bfloyd4445 (Oct 16, 2008)

david85 said:


> That does sound like fun!
> The point of the tests are to see if these batteries can discharge enough current (as claimed) to properly power an electric car up to speed and over hills.
> 
> There was an earlier group purchace that saw lots of EV enthusiests put their money down for thundersy batteries that turned out to have too much internal resistance to properly even allow a car to hold speed let alone have acceptable acceleration. The reserve capacity was better than lead acid, but the the current rating was just not good enough. This piece of history is why I'm going through so much trouble now to see what these batteries can _really_ do before spending on a whole pack.
> ...


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## david85 (Nov 12, 2007)

bfloyd4445 said:


> Thanks for the back ground. I am understanding some of the reasoning behind the madness<smile> If you have a set voltage that must be maintained of say 144 then what you need to do is determine how many amps the battery pack can put out before the voltage drops below 144, or 110, 72,36. Of course this depends upon the characteristic curve of the motor and load your design specifies. My question then is at 1000, 200, 60, amps what voltage do you expect to see?


Voltage sag is part of the reason for the tests. Supposedly, lead acid batteries will have voltage sag of 50% or more in extreme cases. This is why some will run 192V systems even on motors that are intended for only 144V. Because once you "get on it" the car will not have 192 volts at the motor and it will be much lower. Voltage sag is of 50% well known for electric drag racing. It is less for real world driving, but still enough to reduce performance.

Lithium on the other hand is supposed to sag by only about 5-10% within its rated limits. This would not only make for more power, but also better efficiency and that means longer range *for the same amount of amp hour rating compared to lead*. At least thats what I've heard from other observations. Now is my chance to see if this is actually the case in reality.

This is the catch 22 with using a huge lead acid battery pack to get more range out of a conversion (20 6 volt batteries instead of 10 12V, for example). The net efficiency of the car will be reduced, and the heavier it gets, the lower the return in performance because as weight goes up, so too does the amps needed to get it up to speed and over hills. This in turn causes voltage sag that causes lost efficiency. Lead is actually a terrible battery for EVs but its all thats available up until recently. The only reason its even being used is because its cheap to buy.

I'm still not sure how I'll test for 1000 amps because I've been told that my truck only pulls 600 for cold cranking even with the glow plugs on. I'll also need an amp meter that reads that high


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## gmijackso (Sep 30, 2008)

david85 said:


> I'm still not sure how I'll test for 1000 amps because I've been told that my truck only pulls 600 for cold cranking even with the glow plugs on. I'll also need an amp meter that reads that high


The meter part is fairly simple... get two 600A shunts (or four 300A, or whatever), and place them in parallel, then you're capable of 1200A. The metering changes a bit then. Let's say you use two 600A 50mV shunts, place them in parallel and use a single Volt meter to measure them then. This now means that at 1200A, you'll create 50mV. So you take whatever 50mV meter you have and scale it up. So if its a 300A meter you'd have to multiply x4 to get the correct reading.


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## bfloyd4445 (Oct 16, 2008)

david85 said:


> Voltage sag is part of the reason for the tests. Supposedly, lead acid batteries will have voltage sag of 50% or more in extreme cases. This is why some will run 192V systems even on motors that are intended for only 144V. Because once you "get on it" the car will not have 192 volts at the motor and it will be much lower. Voltage sag is of 50% well known for electric drag racing. It is less for real world driving, but still enough to reduce performance.
> 
> Lithium on the other hand is supposed to sag by only about 5-10% within its rated limits. This would not only make for more power, but also better efficiency and that means longer range *for the same amount of amp hour rating compared to lead*. At least thats what I've heard from other observations. Now is my chance to see if this is actually the case in reality.
> 
> ...


so what you need is a load bank, an ameter, a voltmeter, thermometer to measure battery temp under load, and of course your test battery pack. Then you would increase the load on your battery pack while watching the ameter and volt meter untill you have determined the sag voltage at each amperage.
I would think 600 amps is a tough enough test. I've never done anything like this myself but there are companies that have done extensive electric motor testing that may be willing to stir you in the right direction.


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## david85 (Nov 12, 2007)

Yeah, thats the idea. For today I managed to squeeze in another 60 amp test.

Voltage before test: 14.4V
Outside temperature: 10 celsius
Power setting: 5 (60 amps)

Run test........

1:00 - 12.94V <<< 65 Amps
5:00 - 12.80V <<< 62 Amps
10:00 - 12.80V
15:00 - 12.80V
30:00 - 12.78V
45:00 - 12.75V
60:00 - 12.73V
1:30:00 - 12.69V
2:00:00 - 12.68V
2:30:00 - 12.62V
2:45:00 - 12.53V
3:00:00 - 12.42V <<< outside temperature 10 celsius
3:15:00 - 12.17V <<< 61 Amps (the plunge has started....)
3:30:00 - 11.60V <<< 60 Amps
3:35:00 - 11.28V <<< 59 Amps
3:40:00 - 10.85V <<< 58 Amps
3:43:15 - 10.50V <<< 57 Amps (end of load test)

Time/voltage after shut down.........

1:00 - 11.35V
5:00 - 11.86V
10:00 - 12.05V
15:00 - 12.15V

End of test......

What I did differently this time is start the test less than an hour after completing the recharge. This seems to explain the dissapointing result for the last 60 Amp load test, so that mystery is solved. Will start each test from now on with a fresh charge instead of waiting 24+ hours, just adds one more variable that we don't need to worry about. At least not for now. I can now say with confidence that the 3.5 hour run time at 60 amps is the real result and not 2 hours 52 minutes, so I'm done with 60 amp testing. Time to move on......


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## vgslimo (Oct 21, 2008)

question? how are the amps rated? 200 ah for each cell ?


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## david85 (Nov 12, 2007)

vgslimo said:


> question? how are the amps rated? 200 ah for each cell ?


If the cells are wired in series, like these are, then the AH rating is multiplied by 1 and the voltage is multiplied by the number of cells (3.2 x 4 = 12.8V).
If the cells are wired in parallel than the ah rating is multiplied by the number of cells (200 x 4 = 800 ah) and the voltage is a multiple of 1.


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## vgslimo (Oct 21, 2008)

thanks for info.


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## david85 (Nov 12, 2007)

I have an unofficial update. My truck is in the shop for some minor body work, and I took the chance to pull one of the two batteries so I could fit the test sample under the hood.

The vehicle is a 1986 Ford F250 with a 6.9L diesel engine (beat up, but anvil tough). The recommended cranking capacity for the engine is 2000 amps, and I have 2 recent batteries in it that are each rated at 1000CA. I have been told that this engine draws about 400 amps for the starter and 200 for the glow plugs.

What I did was disconnect the alternator, since Tony warned me not to use this battery with lead acid charging systems, and removed the battery on the passenger side (thats where the starter is and thats where the main power is distributed through the truck). I left the other battery in, but disconnected it so that the Lithium battery is doing all the work. I also pulled the connector to the injector pump FSS (fuel shut-off solenoid) so as not to have the engine actually start.

For the first try, the glow plugs were disabled. It cranked off the test battery at least as good as with the 2 lead acid batteries connected, or at least it seemed that way. Tried again with the glow plugs one and I could not tell any difference in cranking performance at all. None of the connections were warm, no funny smells or swelling came from the battery. No data is recorded yet......

I recently got a laser tachometer, so I could use this to verify the cranking speed since the OEM tach isn't accurate enough at any speed, let alone cranking speed. I do not have any way to measure the amps yet however.....

What I take from this is that 1 lithium battery of similar weight to a lead acid starting (not deep cycle) battery can punch at least twice its weight worth of cranking power compared to lead. Quite impressive when you think of some of the first lithium ion batteries that were tried in EVs.

What I'll do next is prepare a 10 second cranking test, since the truck starter can only survive 20 seconds at a time, the battery only 15 seconds (info states 15 seconds or less at 5C, which in this case is 1000 amps) and the glow plugs only 10. Here's where measuring voltage sag becomes important, I'll need some help this time but at least the tests will be brief.


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## DC Braveheart (Oct 12, 2008)

david85 said:


> This is the company website:
> http://www.chinabatterycenter.com/


Hey David85 - thanks for all this useful info - you're doing a heck of a job with this testing. I tried following the link above to find out more info, but I can't find any info there on high capacity cells like the ones you are testing ... is that the correct link?


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## david85 (Nov 12, 2007)

DC Braveheart said:


> Hey David85 - thanks for all this useful info - you're doing a heck of a job with this testing. I tried following the link above to find out more info, but I can't find any info there on high capacity cells like the ones you are testing ... is that the correct link?


Yeah thats it. But it seems to be a little wonky more recently. My antivirus goes nuts when I try to open it. They also changed the website since I first started dealing with them. Before the batteries were more easy to find, now I can't find them either anymore. Needless to say their new website leaves a little to be desired. I suspect they do more of their marketing through other means and that may be why the website is so limited.


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## david85 (Nov 12, 2007)

Well friends, its nearly the end of the line on this testing thread, but here are some results from a 10 second cranking test:

Outsite temperature: 9.6 celsius

Voltage before test: 13.56V

Crank time: 10 seconds

Voltage at 10 second mark (the instant before power is cut): 10.5V

I have no means to measure the actual cranking amps, but I have been told that this engine will draw about 600 amps at the starter and glow plugs. There may be more on top of that for losses, but I can't measure or prove anything.

Heres the setup I used. You can see the battery under the hood and the close up of the crude connection I made into the truck's exsisting battery connector. You can also see that the wires supplied with the battery are not ideal, but seemed to carry the current fairly well anyway. The wires were a little warm after the test.


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## autorama (Nov 7, 2008)

That's pretty impressive. I have a question though. I saw a website called LionEV promising 76v lithium ion phosphate batteries with very impressive(?) stats. Has anyone ever heard of this company or does anyone believe this battery can deliver what it promises?


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## Technologic (Jul 20, 2008)

david85 said:


> Heres the setup I used. You can see the battery under the hood and the close up of the crude connection I made into the truck's exsisting battery connector. You can also see that the wires supplied with the battery are not ideal, but seemed to carry the current fairly well anyway. The wires were a little warm after the test.


Was the battery at 10.5v after the test? or was that what you measured during the cranking? if so, I'd be worried you might have damaged them


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## bblocher (Jul 30, 2008)

Technologic said:


> Was the battery at 10.5v after the test? or was that what you measured during the cranking? if so, I'd be worried you might have damaged them


The TS batteries are rated for 2.5v/cell at discharge. So if those are the same ratings he had a little charge left.


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## david85 (Nov 12, 2007)

autorama said:


> That's pretty impressive. I have a question though. I saw a website called LionEV promising 76v lithium ion phosphate batteries with very impressive(?) stats. Has anyone ever heard of this company or does anyone believe this battery can deliver what it promises?


Be careful with this company. The founder was convicted of fraud (twice). Maybe the problems will be sorted out but at the very least, I would not deal with them unless they were they were across the street. I've heard of more than a few getting burned by LionEV.


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## david85 (Nov 12, 2007)

Technologic said:


> Was the battery at 10.5v after the test? or was that what you measured during the cranking? if so, I'd be worried you might have damaged them


Oh good god no! The voltage drifted back up to about 13.25 a few seconds after the crank test. The 10.5V was the *maximum voltage sag while under load*. The low safe voltage is 9.2V, this means that this test still did not max out the battery according to the specs.

If I had in fact shown only 10.5V with no load on the battery after the test, then it would have been time to put a call into Houston!


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## Technologic (Jul 20, 2008)

david85 said:


> Oh good god no! The voltage drifted back up to about 13.25 a few seconds after the crank test. The 10.5V was the *maximum voltage sag while under load*. The low safe voltage is 9.2V, this means that this test still did not max out the battery according to the specs.
> 
> If I had in fact shown only 10.5V with no load on the battery after the test, then it would have been time to put a call into Houston!



lol that's what I was hoping.

sounds like a successful burst.


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## TexasCotton (Sep 18, 2008)

I think the China company (BYD) and Warren Buffet are going to bring a hybrid vehicle to North America which will use LifePo4. BYD will be selling this hybrid in China in the next six months if all goes well. BYD calls their battery FE6 or something. Anyway China seems to be serious about making LiFePo batterys. 

David how much did you spend on your LiFePo4 battery, what kind of charger do you use, and are you happy with the overal performance so far?


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## david85 (Nov 12, 2007)

TexasCotton said:


> I think the China company (BYD) and Warren Buffet are going to bring a hybrid vehicle to North America which will use LifePo4. BYD will be selling this hybrid in China in the next six months if all goes well. BYD calls their battery FE6 or something. Anyway China seems to be serious about making LiFePo batterys.
> 
> David how much did you spend on your LiFePo4 battery, what kind of charger do you use, and are you happy with the overal performance so far?


I paid about $0.50/ watt hour on the BMS and battery. Charger was supplied for an extra $130 (or just under). Shipping was a killer though, because it came by air mail, it was fast though. Better than if I ordered out of the states (I'm in canada). This is only pricing for the sample, pricing for other batteries has been all over the place so far but generally its $0.50/ watt hour or maybe a little less (before shipping or other costs).

China is dead serious about LiFePO4 though. I was chatting back and fourth with a guy who lives in china (works as a researcher in the field of lithium batteries) and he tells me that its getting a lot of government support. Remember, china will never have enough oil to meet its needs so EV systems are not an option for them.


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## Zemmo (Sep 13, 2007)

You don't want to go with LionEV, our local EV club had some serious problems with them. Their own is also having law problems at the moment with fraud. So I would stay clear of them.


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## OHM (Jun 30, 2008)

Any more updates David? It is very brave of you to go thru such testing and money.

The 200ah cell they sent you is of course of high quality. 
I wonder how good they are in a larger order? This is an issue as when I was asked to order some for testing they offered medium, better and high quality
depending on price


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## david85 (Nov 12, 2007)

To be brutally honest, I was looking for some solid evidence that the batteries were of poor quality and spent many long nights on the web looking for any info of others that are using these cells or cells that are comparable (like thundersky). I have not found any case of a failed LiFePO4 battery except from suppliers trying to put down a competitor, if some one here has heard of a failure than please post it because I want to know.

I've contacted a few guys world wide that are running thundersky batteries and they had nothing but good things to say about them. Granted, they are all running fresh packs.

So far the quality was acceptable. The real test will be when I deploy the full size battery to the car. I have no plans at the moment to continue testing with the 12.8V sample.


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## evcars (Mar 15, 2008)

David, thanks for all the work and posting you have done with the battery testing. Are you going to use the 12 volt sample as the accessory battery?


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## david85 (Nov 12, 2007)

xtreme cartz said:


> David, thanks for all the work and posting you have done with the battery testing. Are you going to use the 12 volt sample as the accessory battery?


Nope. Its too big and heavy for that and simply fitting it would be a challenge. Its powerful enough to replace to the batteries in my diesel truck with cranking amps to spare, so its definitely not needed for a compact car that won't have a starter anymore. The sample will be used for the trolling motor on the boat instead, since it has more that double the run time of the normal deep cycle battery for that application.

We'll either keep the lead acid battery that it came with or downsize to a motorcycle starting battery. The only reason cars normally need batteries that big is to crank the engine over, but this car will only have the headlights as the biggest load, so its not needed after the conversion. Might even try to make a small NIMH battery instead (lithium would need a separate BMS).


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## Boogie (Feb 8, 2009)

I could not help thinking you could need some better equipment for testing your blocks.
I use the CBA-II with an amplifier from West Montain Radio:

http://westmountainradio.com/CBA_ham.htm

This unit can be used at constant current or constant effect.
Drawing a 500W and testing one block at the time, you may have as much as 135A start/test current increasing to as much as 170A if you use constant effect. 
By adding one more amplifier, you can get as much as 270A start current and end up by as much as 340A!!!
That would give you a 1,7C with your 200Ah blocks which is what you would like, to stress test the blocks

You get curves on the screen, and counters tell you exactly how much you get from each block in Ah. You may even layer the curves on top of each other to compare.
When charging the blocks again, you may use it to monitor the charging curves.


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## speculawyer (Feb 10, 2009)

david85 said:


> This is the company website:
> http://www.chinabatterycenter.com/


Where are the automotive sized LiFePO4s on that site? I can't find them . . . or the BMS & charger you got.


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## ElectriCar (Jun 15, 2008)

speculawyer said:


> Where are the automotive sized LiFePO4s on that site? I can't find them . . . or the BMS & charger you got.


Are you thinking of replacing the 12V battery with a lithium? The prior question got me thinking...


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## david85 (Nov 12, 2007)

I was advised against replacing the starting battery with a lifepo because the type of charger could damage the lithium battery.

The company website is limited. Their alibaba account shows the actual products and better contact info:

http://sinoriching.en.alibaba.com/


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## speculawyer (Feb 10, 2009)

ElectriCar said:


> Are you thinking of replacing the 12V battery with a lithium? The prior question got me thinking...


It is a 72V system based on six 12V lead-acid batteries in series. The lead acid batteries are failing. (I think it is just 1 or 2 dead cells but the range has been cut way down.) I'm annoyed at lead-acid and want to move to the future. 

I think I've got a system now:
23 Thundersky LFPs (either 40ah or 60ah)
Those Astro Blinky balancing modules; and
http://www.astroflight.com/index.php?main_page=product_info&cPath=1&products_id=21
a 72V charger made for LifePO4s.
http://elitepowersolutions.com/products/product_info.php?cPath=9&products_id=80

If I put those in there, I think that will replace the six 12 Volt lead-acid dinosaurs. It will be much more expensive, but I think I'll get a better range, it will be lighter, and I won't ever have to worry about replacing the batteries again. (Lead-Acid seems to have a very limited life-span due to sulfation and/or cells that die.)


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## ElectriCar (Jun 15, 2008)

speculawyer said:


> ... I'm annoyed at lead-acid and want to move to the future...


I hear ya! I've got only 800 miles on my lead and I hate it. The truck is under a pretty extreme load in the back, voltage sag is awful to deal with after experiencing a full pack with it's surface charge as well. I love the way mine drives when fully charged. 

Every time I'm trying to maintain speed while climbing a hill and see the voltage drop 15% I say bad words! Knowing what the motor is capable of sickens me watching the voltage sag.

I expect to find an excuse to swap them out sometime next year or maybe this fall.


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## JRP3 (Mar 7, 2008)

That Astro blinky thing is made for A123 cells, are you planning to use A123?


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## ElectriCar (Jun 15, 2008)

Speaking of A123 cells, I've seen the DeWalt 36V battery dissected. Their 36V battery contains 10 3.2V 2.3ah cells. By our calculations they have a 32V battery. In July their cost was about $16 per cell or 160/battery. Now I'm finding them at $99 or $9.9 each. However I believe the battery comes with a built in BMS at this price, just not the charger.

A quick calculation yields a 144V pack requires 45 cells yielding only 73.6ah! To leave the driveway you'd need a few more I believe. For 2250 batteries (50 strings) you would have a 16.5kw pack at a cost of a mere $22,500! 

Weight wise I think it weighs 70grams each so this pack would weigh only 347 lbs plus the bus bars. That compared to my 19kw peukert corrected pack weighing 1500 lbs. That's a 77% weight savings I could live with.

Based on our company use of DeWalt equipment for over 10 years, I don't see the price dropping much in the next 5 years. But then again, I'm comparing it to the old batteries that use Ni Cd technology.


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## JRP3 (Mar 7, 2008)

ElectriCar said:


> A quick calculation yields a 144V pack requires 45 cells yielding only 73.6ah!


Your calculation was a little too quick  45 3.2V 2.3ah cells only gives you 2.3ah at 144V.


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## ElectriCar (Jun 15, 2008)

JRP3 said:


> Your calculation was a little too quick  45 3.2V 2.3ah cells only gives you 2.3ah at 144V.


 Yea, quick draw McElectricar. Just a little mis-labeling, should be .074kwh.


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## speculawyer (Feb 10, 2009)

JRP3 said:


> That Astro blinky thing is made for A123 cells, are you planning to use A123?


No. BBlocher pointed out that they are the right ones to use and it makes sense . . . A123 is just another brand of LiFePO4 chemistry batteries and those Astro Blinkies should work fine with the Thundersky LFPs too. 

Those things handle up to 6 batteries each, so with just 4 of them I could balance my batteries.

The only thing I'm not quite sure on is the number of cells I should use . . . 23 or 24? I'm not worried about the low end of the voltage, I'm more worried about the high end. With 24 batteries if all go to 4.2V that would be 100V going through the system designed for 72V. That is too high. OK, 23 seems better. Maybe 22?


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## Jimdear2 (Oct 12, 2008)

speculawyer said:


> The only thing I'm not quite sure on is the number of cells I should use . . . 23 or 24? I'm not worried about the low end of the voltage, I'm more worried about the high end. With 24 batteries if all go to 4.2V that would be 100V going through the system designed for 72V. That is too high. OK, 23 seems better. Maybe 22?


 
Something that was brought up to me when I first starting asking questions here is that the controller has an absolute "Do No Exceed" upper voltage limit. 

That means that if you exceed that limit, magic smoke is likley. Due to inexperiance, I didn't think about the fact that a 12 volt LA battery can charge up to 14.2 volts, so with that extra battery I was going to put in my fully charged pack voltage would have exceeded the controller maximum and goodby $600.00

I would err on the side of caution. If your pack is capible of being charged to exceed the controller maximum voltage limit then that means that sometime, somewhere it's going to happen.

One seconds inattention could cause thousands of dollars in damage (it does happen). Plus you have to deal with the fact that a lot of these controllers fail at FULL SPEED AHEAD.

IMHO adjust your pack size so the controller maximum voltage can't be xeceeded,

Hope this helps,


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## JRP3 (Mar 7, 2008)

You shouldn't be charging your TS cells to 4.2, I think 3.6-3.8 is what is recommended. They can go to 4.2 but it shortens their life. I'm not sure the same is true for A123, they are a different style of Lithium and may have different characteristics, such as safely charging to 4.2, but I don't really know.
You should be able to find out exactly what your controller will take, if it's rated for 72 nominal a freshly charged pack could come off the charger with an 80 volt or higher charge so it should have some headroom, but I think 24 cells will be too much no matter how you charge them.


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## speculawyer (Feb 10, 2009)

JRP3 said:


> You shouldn't be charging your TS cells to 4.2, I think 3.6-3.8 is what is recommended. They can go to 4.2 but it shortens their life. I'm not sure the same is true for A123, they are a different style of Lithium and may have different characteristics, such as safely charging to 4.2, but I don't really know.
> You should be able to find out exactly what your controller will take, if it's rated for 72 nominal a freshly charged pack could come off the charger with an 80 volt or higher charge so it should have some headroom, but I think 24 cells will be too much no matter how you charge them.


Thanks for the input guys . . . it is very helpful. It gets me thinking and makes me realize my errors.

Assuming the balancing circuits work properly, this charger would max out at 87V such that the balanced cells would only get to 3.625V even if I put 24 of them in there. So the number of cells isn't the important number, it is the charger. And I can limit determine the max charge amount in each cell by selecting the number of cells. (i.e. 3.625V if I use 24 cells, 3.78V if I use 23 cells.) So, 24 cells seems the way to go since this will reduce the operating range of the cells thus making them last longer. Again, this assumes the cell balancer works well and makes sure the cells charge to equal amounts.

http://elitepowersolutions.com/products/product_info.php?cPath=9&products_id=80



TSL72-15
[TSL72-15] Our Price: $336.00








Click to enlarge 
Click to enlarge • *Product Specifications:*

&nbsp- Input: 110VAC single phase 
&nbsp-	Output: 87V/15A DC 
&nbsp-	Suitable for 24 cell pack (connected in series) 
&nbsp-	Recommended Application: 24X 40Ah LFP battery pack with 2.67 hours of charging time


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## ravlegend (Feb 6, 2009)

David-

Thx for testing and posting the results.

Question: where do you get the amp rating for your Minn Kota?
I thought your MK 50 chirps out about 50amp at maximum power?, unless its 1 of the older model so maybe a lesser efficiency? 

I'm searching the power rating of my MK Riptide 55 at different settings. Any idea?


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## david85 (Nov 12, 2007)

I think I was over loading the trolling motor by running at full power in a big tank where its basically pushing against a wall the whole time. When it is pushing a moving boat in real conditions, the amps are indeed only around 50 because the water speed is higher and the motor isn't working as hard.

Motors draw amps relative to how much load they are up against (assuming power input is constant).


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## ScottBear (Sep 20, 2008)

I am new to the site and was wondering where you purchased this battery from. Good info on it.


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## IamIan (Mar 29, 2009)

Just bumped into this forum an hour or so ago ... nice stuff... 
Looking forward to reading up...

Although you probably already know this ... or something similar ... and the testing has had allot of work put into it already... and lots of great data has already come out...

It might be easier in the future to let something like the *CBAII* do the discharge and log the results ... it also would make it easier to latter analyze the test data as you can just export the data to excel and graphs are nice and easy to see the discharge curves with... If you want higher discharge rates than the base unit... you can always add on amplifiers latter ... although personally I've only just used the base unit, as the amplifiers are a bit expensive for my tastes.

Great stuff though..


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## david85 (Nov 12, 2007)

Yeah, thinking back what I did was pretty crude by post war standards lol. But hey, it worked pretty well. I was satisfed enough with the performance that I'm building a car right now that will use the exact same batteries in it. (see link in my signature for the build thread)

Welcome to the forum.


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## david85 (Nov 12, 2007)

I have a small update to report regarding the sample battery.

Since the 10 second cranking test, It has been stored indoors in the basement at about 15 Celsius for 4 months (temp measured with IR thermometer). Today I pulled it out and took readings of the voltage.

~13.4V was measured. Less than a minute after placing it on charge, the charger showed a yellow light, indicating that it detected 80% SOC or higher. Less than 10 minutes later, it went into balancing mode. After 80% SOC, charge current drops of significantly. Once it goes into balancing mode, there is no real charge current that passes from the charger to the battery anymore. Only a light current us used to get the cells balanced together.

What this means is that after sitting for 4 months, the battery had practically no self discharge. I was expecting to see more self discharge than this.

Can anyone tell me of an EV that was ever built that could be charged, then parked for 4 months and not have to be recharged before driving? I don't know of one. This is the lingering problem with NiMh batteries as good as they could have been. Even gasoline evaporates more than this battery did LOL.

There is more to this, of course, like ambient temperature and other variables, but still I think this is a pretty good result and makes me feel very good about using these batteries in my car.


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## speculawyer (Feb 10, 2009)

Maybe this is answered earlier in the thread . . . but where did you obtain this 200AH battery? And how much did it does?


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## david85 (Nov 12, 2007)

Yeah its been mentioned before, but here you go anyway:

http://sinoriching.en.alibaba.com/




Been a while since I looked at their alibaba "booth".........

I think this is my battery. all 48 200ah LiFePO4 cells
http://www.alibaba.com/product-gs/220363630/LiFePO4_batteries.html
Seriously, this is the exact same photo that I recieved before sending the second payment that allowed the goods to be shipped. Also recieved photos of the charger and BMS at the same time (not shown). This photo has been uploaded recently because I never saw it there before.
I wonder if it really is my battery.


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## IamIan (Mar 29, 2009)

david85 said:


> This is the lingering problem with NiMh batteries as good as they could have been.


Only if you chose not to use LSD NiMH ( Low Self Discharge ).
LSD NiMH from what I have seen make NiMH self discharge rates equal to those of the best Li batteries... usually only around ~14% Capacity that self discharged after 1 year... and the rate it stabalizes and slows more and more over time.... see picture bellow. 

My own tests of the self discharge rate of Insight and Civic NiMH batteries will not be done for several months yet... so we will know more about those latter on.


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## Jordysport (Mar 22, 2009)

david85 said:


> Yeah its been mentioned before, but here you go anyway:
> 
> http://sinoriching.en.alibaba.com/
> 
> ...


could you put up some pics of you pack, i have emailed them a week or so ago but had no response back.


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## david85 (Nov 12, 2007)

Jordysport said:


> could you put up some pics of you pack, i have emailed them a week or so ago but had no response back.


I started a thread specifically for updates on the main battery order as I recieved them. .

http://www.diyelectriccar.com/forums/showthread.php/david85s-lifepo4-battery-thread-26272.html

I have a warm contact in the company if you want me to ask some questions on your behalf. May try organizing a group by later if more guys get interested but the first attempt didn't go so well. I think most members are waiting on technologic's sky energy tests because that price is potentially so much lower.


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## david85 (Nov 12, 2007)

IamIan said:


> Only if you chose not to use LSD NiMH ( Low Self Discharge ).
> LSD NiMH from what I have seen make NiMH self discharge rates equal to those of the best Li batteries... usually only around ~14% Capacity that self discharged after 1 year... and the rate it stabalizes and slows more and more over time.... see picture bellow.
> 
> My own tests of the self discharge rate of Insight and Civic NiMH batteries will not be done for several months yet... so we will know more about those latter on.


Thats cool, keep us posted. Any drawbacks for low self discharge batteries? There has to be a reason why not all of them were that way....or was it simply an evolutionary thing?


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## IamIan (Mar 29, 2009)

david85 said:


> Thats cool, keep us posted. Any drawbacks for low self discharge batteries? There has to be a reason why not all of them were that way....or was it simply an evolutionary thing?


Mostly Evolutionary.

LSD NiMH are a newer type of NiMH ... only a few years old... and I've only seen them so far in AAA to D cell in sizes... the D cells are the newest ... I only saw them on the market to buy about ~2 years ago... read about them and saw some prototypes before that.

Becasue they are still the newer type ... they are still less mass prodcuded .. and are still more expensive ~0.89 wh/$1 ... vs ~1.82 Wh / $1 for conventional High Capacity NiMH... so they are still about twice the cost of conventional NiMH.

LSD hold a little less wh/kg than high capacity NiMH... ~75 Wh/kg instead of ~90 Wh/kg... LSD NiMH have a power density W/kg comparable to the high capacity NiMH ~130 W/kg ... but far less than that of the high power NiMH that is used in HEVs .... ~666 W/kg.

LSD NiMH are still young ... but have so far shown to last about twice as many charge cycles under the same conditions as non-LSD NiMH... given the longevity we have seen from original ~10 year old Rav4EV NiMH packs ... a LSD pack not only would self discharge less... and would have more Wh/kg than the ~10 year old NiMH tech would... but the wear rates we see today we would see after about ~20 years of a LSD NiMH battery pack usage... which starts to put NiMH as potentially being a battery that never needs to be replaced during the orerational life of a vehicle.

But... while it is a nice improvement for NiMH ... until they all are LSD and they get more mass produced to bring the prices down more ... it is a step in the right direction ... but it doesn't make them a hands down winner or anything like that ... Li cells still have more Wh/kg ... and that is a big plus for Li for all mobile / portable applications ... which is a big market.

While we know old school NiMH have proven long service life times ... and thus far the newer LSD NiMH are lasting twice as long.... there are some of the newer Li like the LiFePo4 that have shown some very nice progress for Li long term service life as well.

So it still depends on the specifics of the application... but right now I would say that Li is the market favorite ... but NiMH is not out of the game yet... but they are a bit behind in several factors that matter a great deal... Wh/kg being the biggest... NiMH has a good amount x2+ PbA ... but depending on the application good might just not be good enough.

I like reading about the advances in all the various battery options ... it's a hobby of mine 

I'll post about the Self Discharge rates of the Civic & Insight NiMH cells after the testing is done on the thread I started for that ... Don't want to hi-jack this thread... well not any more than I already have


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## david85 (Nov 12, 2007)

I like staying informed too (I do my best)

NiMH is out of the game mainly because of the legal problems. Its probably the reason why the focus shifted so quickly to lithium. If it wasn't for the legal problems, NiMH batteries would be a major player right now. I guess it still is for "light" hybrids, but for electric cars that need big batteries, we have to wait till 2015.

Maybe research will pick up where it left off, I don't know. I do prefer lithium even if I could have bought nickel, but I don't like other good ideas like NiMH getting smacked down like it did.


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## speculawyer (Feb 10, 2009)

david85 said:


> NiMH is out of the game mainly because of the legal problems. Its probably the reason why the focus shifted so quickly to lithium. If it wasn't for the legal problems, NiMH batteries would be a major player right now.


I really don't think legal problems are the issue. By what I understand, it is more the fact that Japanese companies have cornered a lot of the Nickel supply contracts such that it is hard for others to break in. 

And the price of Nickel is relatively expensive such that Li-Ions are a better price/performance.


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## david85 (Nov 12, 2007)

The chinese are baically trying to dump the market with lithium ion batteries, and LiFePO4 in perticular. The seem to be succeeding because lithium battery producers seem to be scaling back production.

There are indeed legal hurdles with NiMH. It would be possible for a private indivudual to assemble a larger battery out of D sized cells (or any other size for that matter), but if you tried to mass produce large size battieries, then there could be a problem. Now if later generations of NiMH batteries are different enough to get a seperate patent, then that might solve the problem.

I'm not sure about nickel supply but typically the metal is relatively valuble as a commodity so that does affect the price of the battery. What was interesting with lithium batteries is that even as the price of lithium went up, the cost of batteries went down because the actual lithium content in a lithium battery is relatively low.

I'm really not all that up to speed with nickel batteries anymore so you probably know more than I do on the points I mentioned.


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## Jordysport (Mar 22, 2009)

david85 said:


> The chinese are baically trying to dump the market with lithium ion batteries, and LiFePO4 in perticular. The seem to be succeeding because lithium battery producers seem to be scaling back production.


yup, cos bolivia won't let any foriegn country get their Lithium, bit of a *** as lithium prices will go up.


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## Mesuge (Mar 6, 2008)

From what I understand the plan in Bolivia is not to play suckers anymore, so lithium mining yes, but you have to also put some higher up foodchain factories and perhaps R&D facilities stateside as well.

Will this increase price dramatically, not really in case of massproduction and massadoption of EVs, which is another topic/question and should be targeted more on big auto/big oil/big gov..


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## genawin (Oct 1, 2008)

"Sinorich , Chinabatterycenter , Zhuhai sanchuan , Sieden". - call them what you like , before making any plans to purchase ask them about thier warranty proceedure, and please post thier response.


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## JRP3 (Mar 7, 2008)

genawin said:


> "Sinorich , Chinabatterycenter , Zhuhai sanchuan , Sieden". - call them what you like , before making any plans to purchase ask them about thier warranty proceedure, and please post thier response.


Did you not get a new charger from them when yours blew?


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## IamIan (Mar 29, 2009)

david85 said:


> Now if later generations of NiMH batteries are different enough to get a seperate patent, then that might solve the problem.


The Cobasys patents apply to but have not prevented NiMH M cells from being made... apparently they aren't big enough and being the last size above F cells that fit under the cut off ... currently NiMH M cells give out about ~26 Ah per cell... for about ~79 Wh/kg.... but less M cells are produced compared to the mass market need for AA NiMH batteries ... so they still cost about ~$27 per cell... or ~1.15 Wh / $1.

Also Large Format NiMH up to 100Ah and 200Ah cells have been availible but it is the minimum quanities that have always provided a barrier for individual use... organizing a larger scale group buys needed have always been plagued with issues no matter what type of product is being bought.

------------

Seperate from the Cobasys Patents for the last ~8 years Nilar Inc . and Electro Energy Inc... have been producing NiMH Batteries that are not effected by the Cobasys Patents... ie different battery design.

Of course Electro Energy Inc ... hasn't been taknig the current economic down turn very well at all... and it is rummoed that they are on deaths door... Of course when they do fall Expect Cobasys to buy their patents.

------------

I think people often forget that Oshinsky did not invent the NiMH Battery... it was arround before him ... he did make important contributions to the advancement of the NiMH battery technology ... and many of the conventional NiMH batteries today are still based on his work... Oshinsky sold it off made plenty of money ... and then moved on to other things... The companies he sold it to have just had large minimum order quantities ... too large for individuals and even some small companies to even consider... at least Patents are not forever ... the Patents in question expire in 2014 ... so by 2015 it won't be an issue anymore... but by then... Li will be even more advanced then it already is today... so it might be a moot point.


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## speculawyer (Feb 10, 2009)

david85 said:


> *The chinese are baically trying to dump the market with lithium ion batteries*, and LiFePO4 in perticular. The seem to be succeeding because lithium battery producers seem to be scaling back production.


This is something I've been wondering about (and should probably start a thread about). The Chinese have made it clear that they are very interested in Li-Ion battery technology and have put a lot of money behind it. So I wonder if the cheaper LiFePO4s we are seeing these days are subsidized or not. If they are, good for us . . . let's buy the cheap batteries . . . but long term it does not bode well for EVs since perhaps that means prices cannot go down much more or could possible go up.?


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## david85 (Nov 12, 2007)

JRP3 said:


> Did you not get a new charger from them when yours blew?


Actually, I'm also interested in knowing what happened.


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## genawin (Oct 1, 2008)

JRP3 said:


> Did you not get a new charger from them when yours blew?


No chance , they decided i must have connected it up incorrectly , i have received regular emails asking if i would like to order more batteries ! but i have given up trying to get a response to the charger problem .

I recently took the cover off the charger and found to my surprise that the BMS is completely seperate to the bulk charger so at least that should be ok.


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## david85 (Nov 12, 2007)

Sorry to be asking this, but the leads on the BMS should be numbered and have to be connected to specific points of the battery pack. Were they connected in that specific order? 

A diagram was supplied with my sample battery as well as the full scale battery. Sample worked fine for me but I haven't assembled the 144V battery yet.

I remember Emily asking me to assemble the battery connections and all and send them a photo first so they can make sure I put it together properly.


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## genawin (Oct 1, 2008)

Yes , i got the diagram and followed it closely , please note that the 25 BMS leads are completely seperate - when i took the cover off the charger recently i noticed that the only thing they have in common is they share the same box, so you could connect them up in any order you like ! - but that would only blow the BMS , in my case the charger blew the first time i turned it on (please don't ask if the polarity of the bulk charger leads were reversed) the factory wanted a picture - i sent them a picture - they said i had connected it up incorrectly - i asked them to explain - thier conclusion was that a lead i had used went off the edge of the photo ?, i sent a second photo showing the lead in full - but they no longer reply to my emails !


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## thetod (Oct 27, 2008)

Which company are you having these issues with?



genawin said:


> Yes , i got the diagram and followed it closely , please note that the 25 BMS leads are completely seperate - when i took the cover off the charger recently i noticed that the only thing they have in common is they share the same box, so you could connect them up in any order you like ! - but that would only blow the BMS , in my case the charger blew the first time i turned it on (please don't ask if the polarity of the bulk charger leads were reversed) the factory wanted a picture - i sent them a picture - they said i had connected it up incorrectly - i asked them to explain - thier conclusion was that a lead i had used went off the edge of the photo ?, i sent a second photo showing the lead in full - but they no longer reply to my emails !


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## JRP3 (Mar 7, 2008)

thetod said:


> Which company are you having these issues with?


The page before this one: http://www.diyelectriccar.com/forums/showpost.php?p=113794&postcount=105


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## thetod (Oct 27, 2008)

So the warranty for all of those are handled by the same people? I understood that they are the same manufacturers but didn't know the support was the same people. That is too bad. 



JRP3 said:


> The page before this one: http://www.diyelectriccar.com/forums/showpost.php?p=113794&postcount=105


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## JRP3 (Mar 7, 2008)

I assumed they are all one company so the warranty would be the same, but I could be mistaken.


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## david85 (Nov 12, 2007)

Its taken a little while for me to understand whats going on, but I think Sieden is a collection of electronic and battery companies including the one I delt with which is called *ZHUHAI SANCHUAN ELECTRONIC TECHNOLOGY CO.,LTD.* Yes, they are listed on Alibaba.

I think this larger group of companies is put together as in a strength in numbers principle for the purpose of competing with other chinese exporters like thundersky (they don't like thundersky LOL), so there may be other companies in there as well. This seems to be a common method of approach when it comes to how the chinese do business. They have a similar website for electric motors that was posted a little while ago on a different thread (WHAT A CANDY STORE THAT WAS!!!). 

If you look up their shop on alibaba you will see ZHUHAI has a VERY wide range of battery and related products likely possible because of multiple different factories feeding the same marketing machine. Emily Cao mentioned that one of the reasons for delay of my order was the charger and BMS were being shipped from another company by truck to their locaion. Only after that could everything be sent to me.

I hope that answers your question.


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## Powered By DC (Jan 3, 2009)

Genawin -check your Private messages 

Dave Kois
Powered By DC, LLC
www.poweredbydc.com


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## thetod (Oct 27, 2008)

So that would make me think that the actual warranty would be handled by the individual manufacturer, not the Sieden collection? If you had an issue with your pack would you go to Sieden or ZHUHAI SANCHUAN ELECTRONIC TECHNOLOGY CO?



david85 said:


> Its taken a little while for me to understand whats going on, but I think Sieden is a collection of electronic and battery companies including the one I delt with which is called *ZHUHAI SANCHUAN ELECTRONIC TECHNOLOGY CO.,LTD.* Yes, they are listed on Alibaba.
> 
> I think this larger group of companies is put together as in a strength in numbers principle for the purpose of competing with other chinese exporters like thundersky (they don't like thundersky LOL), so there may be other companies in there as well. This seems to be a common method of approach when it comes to how the chinese do business. They have a similar website for electric motors that was posted a little while ago on a different thread (WHAT A CANDY STORE THAT WAS!!!).
> 
> ...


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## david85 (Nov 12, 2007)

I would go back to the vendor that originally sold the battery to me (ZHUHAI SANCHUAN). But I've never had to have anything replaced yet, so I can't speak from first hand experience. I was told that warranty was 18 months. We did have another member have problems with his sample cells and last I heard they were replaced after some explaining and photographs.

You could also just fire off an Email and ask what exactly their proceedure is if a battery fails from a defect. 

http://sinoriching.en.alibaba.com/


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## OHM (Jun 30, 2008)

All Im worried about is the samples being better than the ordered pack of final batteries.
If this can be guaranteed it would be the icing on the cake in these hard times.


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## middlenamefrank (May 1, 2009)

speculawyer said:


> Thanks for the input guys . . . it is very helpful. It gets me thinking and makes me realize my errors.
> 
> Assuming the balancing circuits work properly, this charger would max out at 87V such that the balanced cells would only get to 3.625V even if I put 24 of them in there. So the number of cells isn't the important number, it is the charger. And I can limit determine the max charge amount in each cell by selecting the number of cells. (i.e. 3.625V if I use 24 cells, 3.78V if I use 23 cells.) So, 24 cells seems the way to go since this will reduce the operating range of the cells thus making them last longer. Again, this assumes the cell balancer works well and makes sure the cells charge to equal amounts.
> 
> ...


You should check how the balancing circuit in your battery pack works. I believe most of them charge all cells at full current, until they reach some threshold voltage, at which they shut off the main charging current and start charging the cells individually at a much lower equalizing current. So if you're charging a 24-cell pack with a 23-cell charger, it may never reach the threshold voltage and trip into equalizing mode, so the cells may not be identically charged. It all depends on the exact operation of the equalizing circuitry.


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