# Lithium vs Lead Acid - cost for same capabilities



## lowcrawler (Jun 27, 2011)

As you can see in the other thread I started comparing Lead and Lithium and my planning thread I'm looking between Lead Acid and Lithium options.

Unfortunately, in a lot of reading, I haven't found someone compare costs of the two options for something of the same capacity/capabilities. Also, costs for Lithium seem to be all over the place -- from some guy doing a full pack of AA's for like 2.5k to others like me trying to power a small light car and spending 14k+.

So, what is the upfront costs differential between lead and lithium for a system with roughly the same capabilities (for numbers, I'm looking at 10-12 12v (~120aH ?) lead acid batteries ). Costing the LA system is easy (pick battery, multiply, add charger), but costing a LiFePO4 system requires understanding how the system works...which, if it's really 5 digits just for the pack, isn't something I care to spend my time on right now...

(BMS, chargers, etc)


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## tomofreno (Mar 3, 2009)

Just click on the sponsor logos to the right of your screen to see their costs for LiFePO4 cells such as Thundersky or CALB. Then check prices at dealers for Trojan and US Battery flooded lead acid batteries, and Optimus and Odessey for seal lead acid.


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## lowcrawler (Jun 27, 2011)

But it's my understanding that there is quite a bit more that goes 'into' a lithium system than 'just' the batteries. BMS, fancy chargers, compression boxes?, capacitors?, pack heating/cooling, etc, etc...


That said, I did what you said and it seems I've come to the following prices:

NiMh -> $3 per Ah
LiFePO4 -> $2 per Ah
Lead Acid -> $1.5 per Ah

is that about right? (roughly)


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## gojo (Feb 1, 2011)

lowcrawler said:


> But it's my understanding that there is quite a bit more that goes 'into' a lithium system than 'just' the batteries. BMS, fancy chargers, compression boxes?, capacitors?, pack heating/cooling, etc, etc...
> 
> 
> That said, I did what you said and it seems I've come to the following prices:
> ...


Does this take into account the number of expected charges?


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## lowcrawler (Jun 27, 2011)

No, just purchasing the raw batteries. (ie: doesn't include all the 'extra bits' required for Lithium)

I just went to a battery sales place and looked at some of the cheaper varieties on a $/Ah for each chemistry.


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## Jan (Oct 5, 2009)

lowcrawler said:


> But it's my understanding that there is quite a bit more that goes 'into' a lithium system than 'just' the batteries. BMS, fancy chargers, compression boxes?, capacitors?, pack heating/cooling, etc, etc...


BMS is really more needed for lead, than lithium. Lithium has no self discharge, and does not really drift like lead batteries. If you do not abuse them beyond there rates.

Fancy chargers are only needed for higher voltages. Which is not really a Lithium issue, but a result of your motor and controller choice. 

Compression is also not a must, only if you want to get the full 100%, or more, from your lithium batteries. And besides the straps are usually included.

Capacitors are also not needed. Don't know why you think that.

Heating and cooling is also less needed for lithium than for lead. Lead produces more heat, and suffers more from low temperatures.

From lithium you can really get the rated Ahrs. Lead will give you maybe half, if you want to let them last their rated life span.

Voltage sag is a real problem with lead, and not really an issue with Lithium. Which means, you do not only get half the rated Ahrs from lead, but also at a lot lower voltage. kWh wise lead delivers a lot less than you might have hoped for. And that besides the fact lithium gives you initially 4 times the energy per kg. In reallity this can come close to 8 times.

The only reason to go with lead is the initial investment. For instans if you are unsure if your project will be a succes, it might be a good idea to go with lead first. If all turns out well, you know what you might expect from going to lithium.


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## tomofreno (Mar 3, 2009)

Hmmm...I looked at currenttechev and saw 160Ah Thundersky cells, probably the widest used size in ev's, for $200.00, or $1.25 per Ah, so not sure where you got > $2.00. If you search here you find long debates on whether you need to use a bms with LiFePO4 cells or not. Suffice to say if you are unfailing in your attention to your cells during charge and discharge you can do fine without one. If you think you may fail to pay close enough attention occasionally, the bms can prevent overcharge of a cell, and warn you that you are overdischarging one. If you do either to a serious extent, the cell will be ruined. This will add about $400 to $2000 to the pack, depending on pack size and how complex a bms you purchase. As Jan said, lead acid battery performance suffers much more from cold than LiFePO4 does and give you less of their stored energy to do useful work since they have a larger Peukert value. They dissipate more heat internally during discharge, so will heat up more than LiFePO4 cells. There is no need for capacitors for either. You can use supercapacitors to supply higher current during acceleration and then get by using smaller capacity cells, but it is easier, and just as cost effective, to just buy larger capacity cells. The LiFePO4 cells will swell and be ruined if you seriously overcharge them and they are not clamped together (usually done with end plates and strapping, not a box). But if you use a good quality bms, or give unfailing attention during charging, or set your charger to only charge them to 90% capacity or less, that won't happen. No "special" charger is required. It just needs to be programmed to a maximum voltage that won't overcharge your cells, same as it does for lead acid batteries - and if you use a bms it needs an input for the bms to be able to shut it off, or you can use the bms output to power a relay which cuts AC power to the charger. This is all very brief and oversimplified. You will have to spend time searching and reading, and asking additional specific questions to get a better understanding.


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## Yabert (Feb 7, 2010)

Take equivalent comparison....

You thinking about use 120v 120Ah lead cells.....

LifePo4 equivalent can be 38 70Ah calb cells (70Ah x 80% = 120Ah x 50%).
Cost: 38 x 98 = 3700$
Weight: 210 lbs
Cycle: 2000 recharge. 
Power: 69 Kw after voltage sag.

Can you (or someone) compare directly the lead cells with real number?....
Something like:
Cost: 10 x 200 = 2000$
Weight: 750 lbs
Cycle: 500
Power: 55 Kw


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## lowcrawler (Jun 27, 2011)

Looks like the best I can find a 120Ah SLA battery for is 188. (well, given 3 minutes of searching)

So that puts the 'pack cost' of the lead at 1900. ... or roughly half for the same equivalent of LiFePO4. ... and 3 times the weight.

That's a great rule-of-thumb I'll consider as I debate between the two technologies.


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## gsmith191145 (May 1, 2011)

lowcrawler said:


> Looks like the best I can find a 120Ah SLA battery for is 188. (well, given 3 minutes of searching)
> 
> So that puts the 'pack cost' of the lead at 1900. ... or roughly half for the same equivalent of LiFePO4. ... and 3 times the weight.
> 
> That's a great rule-of-thumb I'll consider as I debate between the two technologies.


I have 20 interstate 6v 232ah deep cycle batteries that I purchased from a dealer for 92.00 dollars each. Cost 2005.60 tax included. Lead acid batteries are cheaper than lithium hands down. 

I would require 38 lithium 100ah cells or something close and they are around 5500 plus shipping not including bms and other special stuff. 

I got 3 years out of one set of batteries. about 780 cycles. I paid 1011.42 for my first set of batteries. I will spend less in lead acid batteries than one set of lithiums.


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## GizmoEV (Nov 28, 2009)

gsmith191145 said:


> I have 20 interstate 6v 232ah deep cycle batteries that I purchased from a dealer for 92.00 dollars each. Cost 2005.60 tax included. Lead acid batteries are cheaper than lithium hands down.
> 
> I would require 38 lithium 100ah cells or something close and they are around 5500 plus shipping not including bms and other special stuff.
> 
> I got 3 years out of one set of batteries. about 780 cycles. I paid 1011.42 for my first set of batteries. I will spend less in lead acid batteries than one set of lithiums.


I don't see how you got that you will send less on lead acid batteries. My 40 100Ah cells cost me $5000 so your $5500 figure is in the ball park for the whole thing. $5500/$2005=2.7. If we use your 780 cycles and multiply by 2.7 you get 2106 which is fewer cycles than my TS cells are rated at. I should get 3000 cycles minimum since I don't discharge below 70%DOD very often and I don't over charge (I end charging below 3.5vpc). LiFePO4 cells would take you about a third farther for the same cost.


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## gojo (Feb 1, 2011)

Jan said:


> BMS is really more needed for lead, than lithium. Lithium has no self discharge, and does not really drift like lead batteries. If you do not abuse them beyond there rates.
> 
> Fancy chargers are only needed for higher voltages. Which is not really a Lithium issue, but a result of your motor and controller choice.
> 
> ...


I have a couple of concerns about lithium.

1. I have used lithium battery packs in bikes for several years. My last two packs lasted less then 3years, and I took good care of them. The pack I used the most lasted no longer then the pack I hardly used, so I am skeptical of the 8 or 10 year shelf life they are claiming.

2. It gets really cold here in Minnesota. I can have cold snaps that hit 
-20F to -35F degrees below zero. All I do is store the car in the barn for the winter, A fully charged LA will be good down to -98F below zero, but I don't know what happens inside a lithium stored in sub zero temps. 

Otherwise if you figure the over all miles and performance it would now be foolish to go with normal LA’s. The LA carbon batteries have my interest. I think I could use my present LA charger with the LA carbons, they are 30% lighter, and hold more charge. The LA carbons could end up costing
less then the regular LA’s batteries because carbon is cheaper then lead.


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## lowcrawler (Jun 27, 2011)

Gojo - Can you buy the PbC's anywhere yet that actually exhibit the claims some places are making? I see carbon agm batteries, but they are about 2x as expensive as normal LA and only weigh about 20% less.


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## GizmoEV (Nov 28, 2009)

gojo said:


> I have a couple of concerns about lithium.
> 
> 1. I have used lithium battery packs in bikes for several years. My last two packs lasted less then 3years, and I took good care of them. The pack I used the most lasted no longer then the pack I hardly used, so I am skeptical of the 8 or 10 year shelf life they are claiming.


Were they LiFePO4 or some other chemistry? If they were LiFePO4 what voltage did they get charged to? What C-rate current were they subjected to? How far were they discharged regularly and what was the max discharge? All of these will have an effect on life.



gojo said:


> 2. It gets really cold here in Minnesota. I can have cold snaps that hit
> -20F to -35F degrees below zero. All I do is store the car in the barn for the winter, A fully charged LA will be good down to -98F below zero, but I don't know what happens inside a lithium stored in sub zero temps.


jukka järvinen posted on the EVDL that the cold temperature doesn't hurt them and in fact prolongs their life. He said that he found that heating them shortened their life noticeably. I know with my cells when they are close to 0°C that a >1CA current can cause the terminal voltage drop below 3V with a fully charged pack. I haven't had them colder than that.



gojo said:


> Otherwise if you figure the over all miles and performance it would now be foolish to go with normal LA’s. The LA carbon batteries have my interest. I think I could use my present LA charger with the LA carbons, they are 30% lighter, and hold more charge. The LA carbons could end up costing
> less then the regular LA’s batteries because carbon is cheaper then lead.


Are these available now? I've not seen them for sale any where but then again, since I went with LiFePO4 cells I haven't had any desire to look.


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## lowcrawler (Jun 27, 2011)

So I've done some more looking -- 

I've decided that a ~30 mile range will meet all my consistent needs and that going significantly beyond that simply isn't economical. 30 miles will meet the needs of 95% of my trips (though probably only about 30% of my raw 'mileage'... but I digress)

So, given that, I need about 90Ah @ 120V of lithium or 155Ah @ 120V of lead.

The cheapest I could find that brought in my LA budget to $1700 and 900lbs. The lithium cost is $4275 and weighs 266lbs. Again, for a 30-mile range in a bug.

I don't have cycle numbers for that stuff, but the 'rule of thumb' I've been hearing is that lithiums will last roughly 2.5x as long. So $1700x2.5=$4250. Gee, no wonder there isn't a clear-cut answer here. It's equal almost to the dollar! (market forces at work, perhaps?)

So - basically even up over the life of the pack. But I don't generally hear about BMS and all the other auxillary stuff for lead, whereas those items seem to be mainstays in the lithium world. What up with that?



Given, for me, this will be my first forray into EV's, and the per-day long-term costs (unless someone answers my question above) are more-or-less the same, I think I'll go with lead as that won't lock me into the same setup for 7+ years -- I'll be forced to rejigger things after 3 years or so once I have some experience with the matter. At that point, I can make range decisions based on true use and go from there...


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## GizmoEV (Nov 28, 2009)

lowcrawler said:


> So, given that, I need about 90Ah @ 120V of lithium or 155Ah @ 120V of lead.


Is that 155Ah at the 20 hour rate? I would also look through the evalbum and at other bug conversions to see what their true range is. Also, remember that after the first 50-100 cycles or so the capacity of the lead acid batteries will peak and start to drop again. If you size your pack so it just meets your needs when new you won't be able to use them as long as if you get them a little larger than you need. If 155Ah works for a 80%DOD what are you going to do when the pack capacity diminishes by 90-80% and you can no longer go the 30 miles at 80%DOD of the smaller capacity?

Finally, the old timers say to break in your lead acid pack gently with several shallow low current cycles. This opens up the pores in the paste on the plates and allows them to form properly. High currents with a new battery can literally blow the paste of the plates.

FWIW, here is a bug that is LiFePO4 but it lists energy consumption http://www.evalbum.com/3665. Here is another one with a 96V 170Ah pack at the 20hr rate http://www.evalbum.com/3186.


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## gojo (Feb 1, 2011)

lowcrawler said:


> Gojo - Can you buy the PbC's anywhere yet that actually exhibit the claims some places are making? I see carbon agm batteries, but they are about 2x as expensive as normal LA and only weigh about 20% less.


I haven't seen any for sale. Axion Battery seems to be doing the most to develop them.


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## mizlplix (May 1, 2011)

I am definitely going FLA golf cart 6VDC batteries for my first set. After my car is all dialed in and happy, the second pack will be something better. AND hopefully battery science and manufacturing will have made progress by then.

Also, the more I read about "My battery type is best", the more it gives me a headache. 

This is my third EV. I know how to take care of FLA's (and what to expect). On Lithiums.....There seems to be a club, half swear by them, the other half swear at them. What to believe? 

I agree with gsmith191145. His figures are plain. 

I figured out a 200AH pack for my car, plus cell straps, plus a moderate price BMS, plus a lithium programed charger. $8800.00

Now, do I gamble that they really do last like some people claim? 

I need more development time to be certain. Miz


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## DIYguy (Sep 18, 2008)

There is just no comparison. Sorry to pop your bubbles, but lead is like driving a car with handcuffs on it. Lithium is like driving a regular car. It's better in every conceivable way. Lead EV is almost a waste of time IMHO. Save your money, buy Li.


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## gojo (Feb 1, 2011)

GizmoEV said:


> Were they LiFePO4 or some other chemistry? If they were LiFePO4 what voltage did they get charged to? What C-rate current were they subjected to? How far were they discharged regularly and what was the max discharge? All of these will have an effect on life.
> 
> 
> 
> ...


1.Like I said. I took good care of the batteries. They were LiFEP04's. I charged them with either a 2 or 4 amp charger made for them. I used 15 ah packs, with a 350 amp motor. My normal trips were about 11 miles between charges, and I never ran the batteries down all the way. One pack I seldom used, but kept charged. Both packs went bad in about 3 years. 
　
2.There is a difference between 0C and -35F. A lot of weird stuff starts to happen when it gets real cold. Trees blow up and sound like guns going off, lake ice cracks and it sounds like cannons shooting off. It's a whole other world.
　
3.Not that I am aware, but there was a post in this thread about some AGM's with carbon. I already am driving LA's, and I hope there are some good choices when I replace them. I still use LiFePO4 for my bikes because I need something light, but the car will do what I want it to do with lead, and when there is a clear choice, I will switch, but for now, in my opinion, and based on my experience, with lithium, you just got to believe


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## mizlplix (May 1, 2011)

*sorry right back at you*

It is a question of drive with handcuffs on or walk....I will drive. Not everyone is wealthy or has an EV business to finance their cars. Most adamant lithium answerers work somewhere in the industry and can afford them. 

BTW...in.none.of.my.above posts do I declare fla batterys to be best. Only what I could afford.

Sorry if i offended anyone. Miz


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## DIYguy (Sep 18, 2008)

No offence taken or meant. Just stating the facts as I see it. If I had saved the money spent on lead...the lithium would have come a lot sooner. 

From my perspective, the title of this thread is not even accurate. There is no "same capabilities", although, I know what was intended so, it's all good.


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## Guest (Jul 1, 2011)

*Re: sorry right back at you*



mizlplix said:


> It is a question of drive with handcuffs on or walk....I will drive. Not everyone is wealthy or has an EV business to finance their cars. Most adamant lithium answerers work somewhere in the industry and can afford them.
> 
> BTW...in.none.of.my.above posts do I declare fla batterys to be best. Only what I could afford.
> 
> Sorry if i offended anyone. Miz


Actually many are not in the auto business and many just have ordinary jobs. I have worked my way to where I am but I have to say it took a very very long time to be able to afford anything. My feeling is if you can't afford it don't buy it. If all you can afford is lead and you want to drive your car as an all electric then by all means do so. I don't consider my self wealthy at all but I can afford a decent car. I also buy and sell parts off ebay and CL and then clean and resell for a small profit. That is what I use to fund my hobby. Not my pay check money. Well, maybe some. But very little comes from my paycheck. So I have one hobby to fund the other. You should try it. Be sure you can at least resell for what you put into it. 

Pete


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## gsmith191145 (May 1, 2011)

On another note. I found a lead acid battery that promises over 1000 cycles. 

Lifeline GPL-4C 6Volt Deep Cycle AGM Battery.


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## coryrc (Aug 5, 2008)

*Re: sorry right back at you*



mizlplix said:


> It is a question of drive with handcuffs on or walk....I will drive. Not everyone is wealthy or has an EV business to finance their cars. Most adamant lithium answerers work somewhere in the industry and can afford them.
> 
> BTW...in.none.of.my.above posts do I declare fla batterys to be best. Only what I could afford.
> 
> Sorry if i offended anyone. Miz


Part of the problem is lead is/can be false economy. It wears out the car a lot faster (costs money). You can usually use a smaller car if you use Lithium, which allows you to use even fewer batteries (saves money). You can sometimes get away with a weaker motor and controller because the car weighs so much less (saves money).

For example, say you want 30 miles in a Subaru Justy using a real life comparison:
960 pounds of UB121100 (assuming the extra weight doesn't increase draw)
140 pounds of lithium TK

(It originally had only 480 pounds of lead for under 15 miles)

With the alltrax controller and 6.7" motor, the car wouldn't drive the freeway or very fast without overheating; with the Thundersky batteries its marginal on the freeway but it can, and it handles anything less without issue. You'd save $1000 over buying a 144V Curtis and $1100 over buying a 9" motor. (Not to mention the car wouldn't be safe or have any room in it with 960 pounds of lead in it.) The body of the car would certainly break under the lead load.

So:
$4200 for batteries and BMS
or
$2000 for lead ($170/ea when they were bought), +$1000 for bigger controller, +$1100 for bigger motor, total cost $4100... for batteries with cycle life measured in a few hundred (if you are lucky).

Cory


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## dtbaker (Jan 5, 2008)

gsmith191145 said:


> On another note. I found a lead acid battery that promises over 1000 cycles.
> 
> Lifeline GPL-4C 6Volt Deep Cycle AGM Battery.


retaining what level of original capacity? with what level of average DOD, and at how many amps?

quite frankly, I think it is pretty plain that the large format prismatics (Thundersky/Winston/CALB) will have significantly lower cost per mile over their useful lifetimes if the Manufacturers cycle life estimates are anywhere near true.

yes, they have higher initial cost... like 2.5x more. but when you combine better performance and 4x the life it seems like a slam dunk to me.


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## gsmith191145 (May 1, 2011)

*Re: sorry right back at you*

$4200 for batteries and BMS
or
$2000 for lead ($170/ea when they were bought), +$1000 for bigger controller, +$1100 for bigger motor, total cost $4100... for batteries with cycle life measured in a few hundred (if you are lucky).

Cory[/QUOTE]

Mizplix has an AC motor and controller. Also he has a lester charger that he got for free, 1000.00 dollar savings right there. He has a build blog online. The cost of 2000.00 for lead batteries or 4200.00 dollars for lithium, not a hard guess which one is quicker and cheaper.


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## gsmith191145 (May 1, 2011)

dtbaker said:


> retaining what level of original capacity? with what level of average DOD, and at how many amps?
> 
> quite frankly, I think it is pretty plain that the large format prismatics (Thundersky/Winston/CALB) will have significantly lower cost per mile over their useful lifetimes if the Manufacturers cycle life estimates are anywhere near true.
> 
> yes, they have higher initial cost... like 2.5x more. but when you combine better performance and 4x the life it seems like a slam dunk to me.


What is the warranty on lithiums anyway? 

I have 3 years on my lead acids. 

Also has anyone owned a functioning set of lithiums for ten years.


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## dtbaker (Jan 5, 2008)

gsmith191145 said:


> What is the warranty on lithiums anyway?
> I have 3 years on my lead acids.
> Also has anyone owned a functioning set of lithiums for ten years.


calendar life is largely irrelevant for Lithium... not so for lead which WILL sulfate and suffer reduction of capacity in 2-ish years in most cases. But sticking strictly to useful life (in miles), my point is that if manufacturers claim of 3000 cycles at 70% DOD is true, then Lithium will be far less expensive than lead for same miles under same conditions.

no, nobody has 'worn out' a set of current chemistry Lithium yet that I am aware of.... but that is at least telling us they are running strong after 4 years with normal use... and the vehicle brakes, suspension, and motor perform far better along the way with lower weight.


...but hey, if you don't want to look at facts with an open mind, build your car however you want. It might take an extra $2k or $3k to get that first build rolling with lithium, but the point is that it *should* pay for itself down the road.


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## Guest (Jul 1, 2011)

Well there are some with a good solid daily driving at 3 years and no sign of weakness. Rumor was they would crap out after 3 years. My cells are from 08 and are still going strong. So shelf life is good and even abused they keep on ticking. Better than my lead acid cells.


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## gsmith191145 (May 1, 2011)

What is the warranty on the lithiums?

Who is the best supplier?

What is the conversion calculation from going from lead to lithium. Amp hour rating equivalent.


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## dtbaker (Jan 5, 2008)

gsmith191145 said:


> What is the warranty on the lithiums?
> 
> Who is the best supplier?
> 
> What is the conversion calculation from going from lead to lithium. Amp hour rating equivalent.


warranty is highly dependant on treatment (average DOD as well as average C load and/or extended high C load). manufacturers are waffling a bit, and started low on the conservative side. I think they are gravitating toward a 'qualified' number of cycles around 3000 at 70%DOD, and not over 3C extended pulls. I think 'average' urban/suburban use of 60% DOD and infrequent pulls over 2C are going to yield far BETTER life, but who knows.

'best supplier' is a little tricky. We have had some vendors start out good and then get little questionable due to supply from Thundersky, and at least one who started out fine, and went completely downhill and failed to fill pre-paid orders (like EVC under management of James Morrison). At present I would suggest keeping my eyes open at http://currentevtech.com for some 'sale price' cells that will be hitting the market in the next couple weeks as part of a Settlement liquidation from the EVC fiasco , or consider CALBs from http://www.calibpower.com who has the advantage of direct wholesaler pricing.

lead to lithium equiv is a little harder to quantify because of variables like lead performance under heavy load voltage sag, higher consumption of vehicle on starts due to higher weight, and less efficient charge cycle of floodies with a gassing stage. My personal experience in upgrading from 96v of 8v floodies (185ah-20hr rate) to 120v of 100ah Thunderskies in slightly LESS physical space gives about 20% more range, 30% more available power under load at same wimpy amp limit thru a curtis 1221 controller, and is 500# lighter. My 'average consumption at the plug' including all charge and system losses dropped from right around 500 whr per mile to right around 300Whr per mile over a thousand miles of normal daily driving urban/suburban.


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## GizmoEV (Nov 28, 2009)

gojo said:


> 1.Like I said. I took good care of the batteries. They were LiFEP04's. I charged them with either a 2 or 4 amp charger made for them. I used 15 ah packs, with a 350 amp motor. My normal trips were about 11 miles between charges, and I never ran the batteries down all the way. One pack I seldom used, but kept charged. Both packs went bad in about 3 years.


But you didn't define what taking good care of them means. What voltage did you charge to? With a 15Ah pack if you pulled 350A that is a discharge rate of over 23C! That will be hard on any battery, even ones which are designed for it, compared to 3C or less. The pack you seldom used and kept charged would have lasted longer if you were to keep it at 50% SOC until you needed it. I've also heard different experiences depending on brand. You did what you thought was taking good care of them but maybe that really wasn't what they needed.
　


> 2.There is a difference between 0C and -35F. A lot of weird stuff starts to happen when it gets real cold. Trees blow up and sound like guns going off, lake ice cracks and it sounds like cannons shooting off. It's a whole other world.


Apparently you don't know where jukka järvinen lives and what he has been doing for the past several years. Below is an email he posted on the EVDL about temperature and cell use.

```
Jukka Järvinen [email protected]   Jun 25, 2011 
electrolyte does not freeze in 0 Celsius. I've charged the cells even
below -20 Celsius. Cell outer temperature might be much lower than the
electrolyte. Where the heat need to be. Heating the cells from outside
is slow and you'll end up heating enclosures. Heating elements are
slow and inefficient.

calendar life is related to the temperature and to time how long at
what temp. 5 minutes in 75 Celsius is comparable to one year in 20
Celsius. Then again 5 minutes in 20 celsius is one year in -35
Celsius. Curves are individual for each cell.

-akkuJukka

http://www.google.com/profiles/jarviju#about
```
He also said in another email that he has figured out how to properly care for LiFePO4 packs so that he now gives a 5 year warranty on his conversions.

My comment about my cells at near 0°C was to give people some info to go by. I'm fully aware of what extreme cold can do and that you live in a much colder climate than I do.


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## gojo (Feb 1, 2011)

GizmoEV said:


> But you didn't define what taking good care of them means. What voltage did you charge to? With a 15Ah pack if you pulled 350A that is a discharge rate of over 23C! That will be hard on any battery, even ones which are designed for it, compared to 3C or less. The pack you seldom used and kept charged would have lasted longer if you were to keep it at 50% SOC until you needed it. I've also heard different experiences depending on brand. You did what you thought was taking good care of them but maybe that really wasn't what they needed.
> 
> Apparently you don't know where jukka järvinen lives and what he has been doing for the past several years. Below is an email he posted on the EVDL about temperature and cell use.
> 
> ...


Sorry Giz, I posted a bad word. I meant a 350watt motor. I appreciate you working with me on this, because I would really like to have something figured out when my leads wimp out. Without knowing how to equate the number of C's, other then for a 36 volt pack, and a 350 watt motor, a 15 ah pack was supposed to be adequate. Another thing with electric bikes is the ability to help the motor up hills and into head winds by pedaling , and also being able to slow down and not upset traffic. I have been riding electric bikes for 8 years, and I really try to respect my battery packs. 

I would charge the little used lithium pack about once a month. I kept it in a cool place, and I would simply put the charger on it until the pack was fully charged. I don't know how good the BMS system on the packs is, but they do have them. I have bought my packs from Ping, as most bike people do. I don't know how others have made out with their packs, so any of you E bikers who have been using LiFePO4 for the past few years put out a post, and let us know. Maybe it is just me. 

I was expecting a lot more cycles out of my LiFeP04's, and my experience has just made me skeptical of the 8 to 10 year shelf life they are claiming, and only time will tell. 

I am off to work now but, I will check out Jukka Järvinen later on, and see what he is doing. Again thanks for responding to my post. I am very interested in Lithium in extreme cold. I just keep my bike pack inside in a cool place in the winter, but the car pack needs to stay out in the unheated barn.


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## dtbaker (Jan 5, 2008)

I think there is a big difference between shelf life at low temps and USING the battery at low temps. The manufacturers all say not to charge in very cold temps.... I gotta believe there is a reason.

second.... although the PING batteries are LiFePO4, they look to be very different construction than the large format prismatics we use in EVs. Little packs of cylindricals are going to behave differently regarding heating/cooling.... and max charging at a couple amps and draw of 30amps or so is a different story than charging at 10 to 20 amps and typical draw of 200-300 amps in use in terms of causing internal heat.

best info I have seen indicates it is not a good idea to charge when below freezing, and goal is to maintain around 70 deg F in use.


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## gojo (Feb 1, 2011)

dtbaker said:


> I think there is a big difference between shelf life at low temps and USING the battery at low temps. The manufacturers all say not to charge in very cold temps.... I gotta believe there is a reason.
> 
> second.... although the PING batteries are LiFePO4, they look to be very different construction than the large format prismatics we use in EVs. Little packs of cylindricals are going to behave differently regarding heating/cooling.... and max charging at a couple amps and draw of 30amps or so is a different story than charging at 10 to 20 amps and typical draw of 200-300 amps in use in terms of causing internal heat.
> 
> best info I have seen indicates it is not a good idea to charge when below freezing, and goal is to maintain around 70 deg F in use.


1.This makes me wonder about the Leaf. They are not being offered for sale in Minnesota at this time. Maybe for good reasons. 

2.I also think the EV LiFePO4's are made better then the little bike LiFe's, and I think the EV batteries would last longer then 3 years, but for a guy like me that only drives his EV one or two K a year; even at ten years I would only get 10 to 20 K miles at a cost of $10 K for the batteries, BMS and charger. This would come to somewhere between 50 cents to a dollar a mile for the batteries, and this would be best case scenario. 

To really get the value out of a 10 year shelf life pack of lithium batteries, one would have to drive my EV more then I do. I can get about 6 K miles out of a $450 lithium bike pack, or about 7.5 cents per mile. This is about 600 charges at about 10 miles per charge in 3 years. If the batteries lasted another 2 years, I could possibly get the full 1000 cycles they are possibly capable of doing, or if I rode my bike more, I could possibly get the extra cycles. I am merely pointing out the importance of shelf life and the number of miles driven with EV's.

I know someone who used the same LA pack for 8 years here in Minnesota. The batteries were not taken real good care of, and they may have lasted longer. The batteries were stored outside in the winter, and I believe the cold added to the shelf life. If I do the numbers with LA; my 120 volt 150ah pack costs $2 K, if the pack lasted 8 years, and I drove 1 or 2 K a year; I would end up paying between 12.5 and 25 cents a mile, or about 1/4 of what lithium would cost me. Maybe with better care the LA's could last a couple of more years and I could get it down to 10 cents a mile, or maybe my LA's will only last 4 years, and I will be paying 25 to 50 cents per mile; time will tell. 

Any low mileage EV owners care to comment on the shelf life of their Lead Acids? I would assume there would be more low mileage EV drivers in the colder climates, so cold weather storage would be an important factor.


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## dtbaker (Jan 5, 2008)

gojo said:


> Any low mileage EV owners care to comment on the shelf life of their Lead Acids? I would assume there would be more low mileage EV drivers in the colder climates, so cold weather storage would be an important factor.



you don't want 'shelf life'... you want a pack with thermal management so that you can drive it under all conditions all year...


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## GizmoEV (Nov 28, 2009)

dtbaker said:


> I think there is a big difference between shelf life at low temps and USING the battery at low temps. The manufacturers all say not to charge in very cold temps.... I gotta believe there is a reason.


But no one seems to know the reason or at least isn't willing to share it. The couple of times it was cold enough to get my pack down that cold I was glad to see that after pulling only 10Ah out of my 200Ah pack, part of it at 250A, that the case temperature was above 0°C so I would immediately charge when I got home so it was charged before the pack temp dropped again.



> best info I have seen indicates it is not a good idea to charge when below freezing, and goal is to maintain around 70 deg F in use.


That is what I was thinking until jukka järvinen said that heating the packs shortened their life. I wish his website was still up with his data. Something about someone admin passworded everything? When I looked at his site a year or so ago he had pictures of some cell testing he was doing which included cycling cells while in a deep freeze. He was working on an eCorolla design which would be easy to implement for anyone. I don't know where things stand on it at the moment. I figured he must know something about what he is doing since he is giving a 5yr warranty on TS batteries for cars in a cold climate.


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## GizmoEV (Nov 28, 2009)

gojo said:


> 1.This makes me wonder about the Leaf. They are not being offered for sale in Minnesota at this time. Maybe for good reasons.


The Leaf uses LiMn batteries which changes their properties. I heard that the next model will include battery heaters to warm them up just enough to satisfy the electronics.



> I am merely pointing out the importance of shelf life and the number of miles driven with EV's.


This is a point easily missed. In looking at that, however, don't miss the many other benefits of a LiFePO4 pack.



> Any low mileage EV owners care to comment on the shelf life of their Lead Acids?


I got 5000 miles out of my Trojan T-875 lead acid pack. I do not know how many miles the previous owner put on them but they looked quite new when I got my Gizmo so I doubt there were very many miles on them. I have a hill to climb to get home and I have to pull over 250A for a couple of minutes. Members of the OEVA cringed when I told them the currents I was pulling from 8V flooded batteries. I'm sure this didn't help the life any.

This rig started out as a 20mile rig and the range had dropped to a little over 10 miles. This represents 2 years of driving if I subtract the 1 year of down time plus what ever the previous owner did.

Now, install the LiFePO4 pack. I went with a 20 cell 200Ah pack so my nominal voltage went up but my useable mileage went from 20 miles to 70 miles. If I had kept the same nominal voltage I would have had a 52 mile pack. What this did was drastically increase the useability of my car. This pack was installed January 18, 2010 and as of July 1, 2011 I have put 7994 miles on it. This huge increase in use is mostly due to the increase in range and only partly due to the increase in top speed. It was 40mph and now it is 50mph. Besides the fact that I no longer have to clean acid off the battery tops and water the batteries monthly I don't have to keep the batteries topped up. I can go several days between charges if my range needs are modest and if the unexpected comes up I can still go the distance. For example, Friday morning I had 16 miles on the pack since last charge. I expected only to need 10 miles of range so I didn't bother charging the night before. Two other items came up and I ended up driving 34 miles. A day I could not have done with the lead acid pack because there was no option to opportunity charge. Useability is worth something and until you drive an EV with a LiFePO4 pack and not the lead it used to have you really don't know what you are missing. Just like I don't expect my 22" wide screen computer monitor to pay for it self but I can guarantee
that I won't be going back to my 14" CRT.


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## tomofreno (Mar 3, 2009)

> That is what I was thinking until jukka järvinen said that heating the packs shortened their life.


 I think he meant OVERheating them shortens their life, not just keeping the warm. Or he may mean heating them up at too high a rate which could result in high solvent temperature. I wouldn't worry about LiFePO4 in cold, but I would insulate the battery boxes well and use battery heaters to keep them 50 to 60F. Heat is the greater problem I think. Yesterday was a record 118F in Phoenix, 48C! Probably 135F, 57C, or more in a parked car in the sun.


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## EVfun (Mar 14, 2010)

lowcrawler said:


> But it's my understanding that there is quite a bit more that goes 'into' a lithium system than 'just' the batteries. BMS, fancy chargers, compression boxes?, capacitors?, pack heating/cooling, etc, etc...
> 
> That said, I did what you said and it seems I've come to the following prices:
> 
> ...


I keep being drawn back to the thread title and some initial assumptions. A Lithium battery pack will need a better charging system than a flooded lead acid pack, but likely simpler charging system than a sealed lead acid battery pack. Unless you are going with golf cart batteries (where charging can be cheaper and rather crude) I would consider this a wash at best and favoring Lithium in some cases.

The need to keep the cells from swelling (generally for Winston and CALB cells) is debated. Positive pressure isn't required. However, clamping is cheap and easy to accomplish. A few sections of aluminum plate and some banding strap material will cover it. 

Pack heating/cooling doesn't favor either lead of Lithium. Both sag more when cold. Thermal management is a good idea in extreme climates for either chemistry.

The price for different batteries should be compared in price per watt hour, not amp hour. Watt hours is stored power. Lead acid cells are about 2 volts each, LiFePO4 cells are about 3.2 volts each. Nimh cells are nearly unavailable in EV sizes. 

Lead acid (Optima) $0.40 watt hour [1]
LiFePO4 (CALB) $0.41 per watt hour [2]

[1] based on a price of $160 for each for Optima group 34 yellow tops. This price is often available if buying 10 or more batteries. AGM type lead acid batteries have only about 60% of their capacity available at EV discharge rates. The price per amp hour would $0.24 if all 55 amp hours where available. 

[2] based on a price of $1.30 per amp hour for CALB cells. The nominal cell voltage is 3.2 volts resulting in a price of $0.41 per watt hour. The expected cycle life is much greater than Optima batteries. 

I am in no position to give pricing information for golf cart batteries. I quit using them years ago because they do not give me performance I find acceptable. I suspect the price would be around $0.15 to $0.25 per watt hour. They have greater cycle life than most sealed lead batteries but not nearly as long is the rated cycle life of CALB or Winston Lithium cells. 

One part of the cost being left out is what must be done to the rest of the vehicle to handle the battery pack. Lead acid packs that provide a range greater than 20 miles almost always require beefing up the suspension. The cost of this varies greatly between vehicles, but needs to be taken into account when figuring the actual cost of a chosen battery type. Lithium packs often require little to no suspension work because they make much smaller changes to the vehicle weight. With Lead acid batteries you have around 10 watt hours per pound available, while Lithium cells will provide about 40 watt hours per pound of pack weight.


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## GizmoEV (Nov 28, 2009)

tomofreno said:


> I think he meant OVERheating them shortens their life, not just keeping the warm. Or he may mean heating them up at too high a rate which could result in high solvent temperature. I wouldn't worry about LiFePO4 in cold, but I would insulate the battery boxes well and use battery heaters to keep them 50 to 60F. Heat is the greater problem I think. Yesterday was a record 118F in Phoenix, 48C! Probably 135F, 57C, or more in a parked car in the sun.


It may be that he didn't heat them slowly enough. He said that by trying to heat them some parts of the battery were heated more than other parts which led to localized damage. I don't know but if he can warranty a battery pack for 5 years and doesn't heat them he must be doing something right.

I was thinking of adding some sort of heating pad for my batteries and only heat them to 15°C since they do just fine at that temp for my needs. With a 200Ah pack I pull at most 2CA momentarily and am usually pulling less than 1C.

I've wondered about these cells in your kind of heat. It will be interesting to see over time if cells in some climates die sooner than in other climates. There are so many variables that it may be hard to tell what is climate related from other factors.


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## MN Driver (Sep 29, 2009)

The only issue with battery heating to a standard room temperature or a little under is if the heating pad, wired, or strips that are being used are not setup in a way that will spread the heat out evenly. There have been a few pictures I've run into with both lead-acid and ThunderSky cells where the cases have had burn marks on them. The thermostat of the heaters were mounted on the top and a very thin sheet of aluminum didn't spread the heat and pretty much went right directly above where the strip was and made some bad smells. I'm not sure where the picture is at but there is a picture somewhere that was on this forum showing yellow Thundersky cells with thick 1"(2.5cm) wide black marks on the bottom. ...that sort of heating is what you want to avoid because at the bottom of that cell is going to be overheated and likely the top still cold.

My plan is to use a heating method that contains very small flexible wires that I can lay in a uniform pattern and put a thermal sensor or better yet a thermal fuse somewhere directly between the wire itself and the battery so that it will fail to off at 120 degrees(50c) or higher and a thermostat on the top or otherwise opposite end of the cell to shut them off at a temperature where they are warm enough which I'll think 50 degrees(10c) is plenty of warmth if the pack isn't sized small for the application if I was on the bare edge of performance and couldn't give any up in the winter I might heat to 70 degrees(20c) but I really don't think that even then it would be necessary unless it was a matter of heating the pack and then driving somewhere to park for 12 hours, but then I'd be interested in getting a good layer of thick rigid foam insulation and a method of air barrier in there, which is my plan as well.


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## gsmith191145 (May 1, 2011)

GizmoEV said:


> Now, install the LiFePO4 pack. I went with a 20 cell 200Ah pack so my nominal voltage went up but my useable mileage went from 20 miles to 70 miles.




Gizmo I thought you said that you had 40 100ah Cell's not 20 200ah cells? Just trying to get correct data. Which is it?


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## tomofreno (Mar 3, 2009)

> I've wondered about these cells in your kind of heat.


 I don't live in Phoenix, just saw the temp on the net news. It is about 99F in Reno today. I drive the ev in those temps but wonder if I am sacrificing life cycle time of my cells doing it. Highs are usually in the 95 to 105F range from mid-July through mid-Aug. I drove 24 miles yesterday, mostly at 50-55 mph when it was 98F and the car had been sitting in the sun for about 5 1/2 hours. Motor was at 61C, controller at 54C when I arrived home. The controller remained at 47 - 48C for most of the trip until I hit a several mile stretch of highway on which they had recently applied black tar. The controller temperature rose about 6C after a couple miles of being on that road. The air felt much hotter too. I didn't check the cell temps, but last summer they were up at 105-115F or so in such temperatures. I don't see how they could handle Phoenix without some form of cooling.


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## GizmoEV (Nov 28, 2009)

gsmith191145 said:


> Gizmo I thought you said that you had 40 100ah Cell's not 20 200ah cells? Just trying to get correct data. Which is it?


I have a 2p20s pack so yes, 40 100Ah cells. I said 20 cell 200Ah pack because saying it otherwise confuses some.


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## bruceme (Dec 10, 2008)

I replaced roughly 8kwh useful of PbA with 14kwh of LiFePO4 TS about 18mo ago. I commute 30mi ~150 days a year in my EV (My wife and I car pool in the summers). I can't emphasize the improvement lithium makes in all regards. Maintenance, weight, cost, performance, longevity. It's just better everywhere. Let me put it plainly:

Do you want to led sled?
Do you want to spend the time and money replacing your batteries every 2 years? 
Do you want to fill with water every few weeks?
Do you want to check every cell every few weeks to make sure they're still ballanced?
Do you enjoy knowing your batteries still have half of their potential electrons stuck in them when you're stuck on the side of the road?
Do you want to worry about heating the batteries when it drops below 50 at night? 
Do you want to worry about using too much throttle because you get so much less energy back?

A low maintenance Lithium system needs a BMS (or you'll be risking expensive batteries). Lithium has a low peukert exponent, they perform better under heavy load. They age well and can take 4-8 times more charge cycles before becoming solar energy storage. If you look at the total cost of ownership Lithium is cheaper, hands down. Just do the math.

Lithium doesn't fix everything... It's less sensitive to temperature, but bellow about 30 degrees, it's really not happy. So if you want to drive in those temperatures, you will need an insulated battery box with a heater, but that's not hard to make. Mine took about 50hrs.

-Bruce


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## Guest (Jul 6, 2011)

> A low maintenance Lithium system needs a BMS (or you'll be risking expensive batteries).


I disagree. If you want to spend the money for a BS system that is alright but for me I'd rather spend that on a few extra cells and have a bit more range. I let my controller and charger do the work of keeping the charge/discharge where it needs to be. No need for an extra complex system. They are quite robust and if set up correctly can live happily keeping them off the top and bottom. You still have your useful range and power available. No need to squeeze out every last tid bit of power. There really is not much useful on the top or bottom anyway. So leave it be.


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## gojo (Feb 1, 2011)

bruceme said:


> I replaced roughly 8kwh useful of PbA with 14kwh of LiFePO4 TS about 18mo ago. I commute 30mi ~150 days a year in my EV (My wife and I car pool in the summers). I can't emphasize the improvement lithium makes in all regards. Maintenance, weight, cost, performance, longevity. It's just better everywhere. Let me put it plainly:
> 
> Do you want to led sled?
> Do you want to spend the time and money replacing your batteries every 2 years?
> ...


It will depend a lot on how long my present LA’s hold up. If they last a couple of more years, the LA carbons may be available. I saw some for sale in Europe now. A 160 ah 12 volt weighed 49 pounds, and was expected to offer 1500 plus charges. This would be pretty tempting if I could use my existing charger. 
On the other hand lithium may have more to offer in a couple of years. For now, there is just a lot we don’t know about them. My experience, as I posted earlier, with electric bike lithium packs makes me a little skeptical of some of the claims being made, and only time, and experimentation will tell.
I am in no way minimizing your post. I really like my LiFeP04 bike pack. But for now, my EV does what I want it to do with the LA's. My 100 ah 120 volt pack gets me to work and back (23 miles), gets me to the grocery store (7 miles), gets me to the girl friends and back (18 miles), and if I need to go further, the park and ride is 7 miles.


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## bruceme (Dec 10, 2008)

gottdi said:


> I disagree. If you want to spend the money for a BS system that is alright but for me I'd rather spend that on a few extra cells and have a bit more range.


Please do... and I never said you had to have one period... but if you don't want to worry about your batteries all the time, you do. And they aren't that expensive, the miniBMS system for a 144v is $500. That's 5 of 44 cells or 12% of the cost. I paid more in taxes, heck I paid more in one year's insurance.



gottdi said:


> There really is not much useful on the top or bottom anyway. So leave it be.


Not about using all the charge (I use about 60% on my round trip)... it's really about the cumulative effect of slight variations in the cells. Sure, I can balance them manually once a month or I can pay $500 for technology to do it for me and not worry about it.

-Bruce


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## dtbaker (Jan 5, 2008)

bruceme said:


> it's really about the cumulative effect of slight variations in the cells. Sure, I can balance them manually once a month or I can pay $500 for technology to do it for me and not worry about it.
> -Bruce


*so far* I haven't seen the cells drift enough to require any intervention. I checked after 1000 miles and they were pretty much right where they started. Coming up on 2000 miles so I'll check again soon and report. If needed I'll tweak manually, but so far am feeling fine about not introducing the exta complexity and possible points of failure of a BMS.

I figure if I only need to check every 6 months, it will correspond to when I button up the lids and insulate for winter, and remove in spring....


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