# LiFe(Y)PO4 as starting battery for ICE car?



## EVfun (Mar 14, 2010)

I doubt they have a longer cycle life in this application. Starting batteries only have about a 10 cycle life if deep cycled but about a 5000 cycle life at 5% depth of discharge. That is why a starting battery can often last over 5 years in an ICE automobile. The DOD is very shallow starting a car, a few hundred amps for only a few seconds.


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## MN Driver (Sep 29, 2009)

The cost IMHO isn't worth it. The lifespan of a lead-acid battery is long enough where the two or so that you replace in a 10 year lifespan is going to cost less than 4 LiFePO4 cells.

Plus you will have a tough time if you live in a cold climate like I do because the lead-acid specified for your vehicle will likely outperform, say, a Headway LiFePO4 when temps drop below -20. I've thought of it too until I did some research on cold temperatures and LiFePO4 and I just wouldn't go for it unless you want to do a guess and check setting your freezer as cold as you can and tossing the cells in overnight and pulling them out and attaching them to your car to test, but then again the oil isn't as thick as it would be at winter temps either so you'd want a step up from even that. Not to mention you'd want to pull them to do a balance charge here and there too to keep them in check. More effort than its worth even if the cost were the same for the application. ...plus if you ever leave a dome light on or headlights on and you drain the cells they are done. Lead-acid is more forgiving to that sort of mistake. Just my opinion however, it seems to work for guys who off-season their motorcycles and other 6v and 12v vehicles that hate that they have to trickle these things every other month to keep them alive. ...for a daily driver in the winter, I think otherwise.


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## rwaudio (May 22, 2008)

I would say the only benifit would be reduced weight, or if your normal use discharges the starting battery more than usual. IE big stereo, winch, off road lights used when the vehicle isn't running.

If you are a "typical" user that just starts the car with it, and you aren't trying to remove every pound possible then just stick with lead. They actually do work well for that (but that's about it).


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## vpoppv (Jul 27, 2009)

Not that OEM's are the epitome of engineering, but the scant few hybrids and EV's out there have historically kept the accessory battery as lead/acid- so there must be a reason. As far as using in your car, how were you thinking of charging your lithium cells? An alternator AFAIK would not charge to a high enough voltage to make your cells happy. And I am asking this because I am considering doing the same thing, not because I want to deter you from doing so....


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## Automcdonough (Sep 1, 2010)

That part always bugged me, in that situation the 12v can be replaced with one or two of those multi-farad capacitors.


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## dtbaker (Jan 5, 2008)

vpoppv said:


> Not that OEM's are the epitome of engineering, but the scant few hybrids and EV's out there have historically kept the accessory battery as lead/acid- so there must be a reason.


purely cost... if a $100 lead battery does the same job as $400 worth of lithium, the OEMs stick with lead. Especially since buyers are the ones replacing the batteries when they die after 48 months.


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## rmay635703 (Oct 23, 2008)

If you drive for fuel economy and have removed your alternator this might be worthwhile, otherwise I would worry that you would overcharge the lithium battery into oblivion.


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## AJN (Nov 1, 2009)

I'm more worried about overdischarging than overcharging. If the alternator is ok it wont take your battery over 14.4 volts (3.6 V per cell), but if you forget the lights or something else on there is nothing to prevent the disaster

_Plus you will have a tough time if you live in a cold climate like I do because the lead-acid specified for your vehicle will likely outperform, say, a Headway LiFePO4 when temps drop below -20_

How about these LifeYPo4s? Would they survive in cold climate?


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## MN Driver (Sep 29, 2009)

AJN said:


> How about these LifeYPo4s? Would they survive in cold climate?


They will still have high internal resistance, a 40Ah cell likely won't handle it in the cold, in fact 4 Headway 8Ah power cells in series will probably do better than 4 of the 40Ah of Thunder Sky in series at frigid temperatures.


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## raikkonen (Apr 5, 2011)

I'm also interested in this topic...
I want to replace lead acid for space and weight reasons.
My question is, seems I don't need an overcharge, but I do need an undercharge protector.
Moreover, do I need a balancer circuit?
If so, if there something specific?


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## tweaker (Apr 7, 2011)

raikkonen said:


> I'm also interested in this topic...
> I want to replace lead acid for space and weight reasons.
> My question is, seems I don't need an overcharge, but I do need an undercharge protector.
> Moreover, do I need a balancer circuit?
> If so, if there something specific?


Check out these. I'm waiting for some expertise in another thread but they are very attractive price-wise. They will have overcharge protection and I hear are talking about undercharge protection later in the year. http://www.shoraipower.com/
Apparently they have very good American product support.


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## dtbaker (Jan 5, 2008)

if they are Li based, they will not 'self-discharge' like lead will, but that is only an issue if the car sits for long periods. Li does NOT like huge loads though, which creates internal heat, which shortens the life, which is probably why they are talking about a 2 year warranty where you can get 80 months out of a good lead starter battery.

unless the cell pack is designed such tha tthe max output 'charging' voltage from alternator is within safe max voltage of the cell chem... you may be asking for trouble. i.e. if it is just 4x3.2v cells, the max voltage from alternator had better be no more than 4x3.8 or you will be frying cells.

I would say using LiFePO4 as a started battery is 'probably not' a good idea.


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## raikkonen (Apr 5, 2011)

Alternator voltage is typically regulated to 14.4V, so 3.6V for a 4s pack.
I think it's something around 70%...


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## bruceme (Dec 10, 2008)

KirillSp said:


> Hello all,
> 
> I know, a little bit OT (because EV forum), but I know, here are many experienced people, thats why I ask here:
> 
> ...


The world has too many nay sayers. LiFePO4 will have a future in aviation batteries first (weight), but once they have proven themselves they will make their way into cars for all the same reasons. They do require more care and feeding and expense but just give it time. Besides... we're going all electric soon anyway, right 

-Bruce


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## WSJ (Sep 18, 2008)

Porsche's Weight-Saving Lithium-Ion Car Battery

Weight is the enemy of fuel economy on the highway and quick lap times on the track. Porsche has one solution in the form of a lithium-ion replacement starter (main) battery that weighs in at just 13 pounds vs. 35 pounds for the traditional lead acid battery. "Less weight naturally means greater agility and driving dynamics," Porsche notes in its release. This four-cell battery runs $1,700 which, Porschephiles will be quick to agree, isn't all that much for a Porsche option. It's available on the 2010 Porsche 911 GT3, 911 GT3 RS, and Boxster Spyder. You get the standard lead acid battery as well and the two can be quickly swapped for track days.

Porsche says the two batteries have the same fastening points, connections, and voltage range. Dimensions are the same except the lithium battery is 2.8" lower. It has a capacity of 18 amp-hours vs. 60 Ah for a standard lead-acid battery, but the lithium-ion battery delivers all its power, Porsche says, while a standard battery delivers about 30% of what's available. Porsche also says the lithium-ion battery has more charge-discharge cycles and is quicker to recharge. Porsche recommends against using the lithium battery below 32 degrees because of its characteristics. You can charge it and jump-start like a normal battery and the internal electronics protect against overcharge situations. 

http://www.gearlog.com/2009/11/porsches_weight-saving_lithium.php


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## AJN (Nov 1, 2009)

So, has anyone tested modern lithium chemistries as a lead acid replacement in ICE cars? A123 20Ahs in 2p4s-packs or something similar?


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## rochesterricer (Jan 5, 2011)

Plenty of people have tried it in cars:

http://honda-tech.com/showthread.php?p=44171160#post44171160

Even more have done it in motorcycles. You can actually buy commercial models now, as linked to a few posts above yours.


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## AJN (Nov 1, 2009)

rochesterricer said:


> Plenty of people have tried it in cars:
> 
> http://honda-tech.com/showthread.php?p=44171160#post44171160


I was interested about people's experiences, thank you for the link. Those are Headway 38120S cells right? The problem with these is the temperature range, manufacturer says they can be charged above -10 Celsius and discharged above -20. That works in warmer climate, but not in here where I live.

http://www.chinaheadway.com/en/productsh.asp?id=187

LiFeYPo4 can be charged and discharged to minus 45 Celsius (according to Winston Battery), but its cold performance is poor as MN Driver said.

http://en.winston-battery.com/index.php/products/power-battery/item/wb-lyp90aha?category_id=176


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## MN Driver (Sep 29, 2009)

It depends on what performance you need out of them and if you are willing to deal with a quirky start to warm them up if they don't perform as well in the cold as you need them to. Unfortunetly I haven't seen anyone cold test these cells and document much of anything yet. I nearly had my hands on some 100Ah TS cells to do this kind of testing but I haven't heard back from that person in awhile. It sucks because I have a 500 amp load sitting here doing nothing waiting for a cell or cells to test this with. For all I know they might start a car just fine, lead-acid batteries sag in the cold too and usually we look at LiFePO4 cells and see much smaller amounts of sag and consider them saggy. The only real test would be to buy them and see if they perform. Of course its a little risky on a $$ perspective if it doesn't work. I'd personally go with 38120P cells from Headway.


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## ElectriCar (Jun 15, 2008)

I tried a "factory" assembled unit in Shorai and Ballistic, they largest size they offered on my '09 Harley Ultra V twin. Both failed in comparison to a failing factory battery. It will start in about one second with a good battery. The Shorai took about 3 seconds IIRC and the Ballistic 16 cell took about 2 seconds. Not a terribly long time but in comparison to 1 second, it's very slow and it concerned me. I'm going back with lead for the time being.


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## AJN (Nov 1, 2009)

Hello Electricar

What was the capacity of the original lead acid and those replacements you tried?


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## ElectriCar (Jun 15, 2008)

Original was a 27 but the manual said 30. The Shorai was a 36 and the other a 28. The problem is they both allowed the voltage to drop too low and were unable to deliver the amperage they were rated at. 

My failing battery could deliver about 400A IIRC when I measured it. They both failed to deliver that much. Very disappointed to say the least. Spent all that time working to make them fit and was totally disappointed. May be that they are using cheap cells or just engineered poorly, IDK. 

The thing is they charge a lot for them and still wouldn't do what they advertised. Had they worked well I was considering getting a small one for my riding mower which I may have never had to replace.


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## JRP3 (Mar 7, 2008)

Bill Dube, (Killacycle), has reported using a 12V Lithium battery in his truck in Colorado for years, even in the cold. I assume they are A123's since that's his sponsor.


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## jeremyjs (Sep 22, 2010)

I really don't see what the problem would be other than the fact that you don't want to ever over discharge them and you want too use a quality cell to handle the short term high draw of starting a car in the cold. The charge voltage off your alternator is in the correct range and you could use a blinky cell balancer too keep them balanced. 

Seems like the biggest drawback would be that you can get a good lead acid that'll last 10 years under everyday use for less than half the cost. I had the same optima red top in my last car for 10 years and it was still going strong when I sold it.


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## JRP3 (Mar 7, 2008)

Actually the big issue may be charging in the cold, that may be when the worst plating occurs. The discharge current from cranking may be enough to locally heat the cells when the motor starts, or not. I'd at least do an insulated battery box, maybe with a heater for really cold nights.


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