oldtrlrnr

Psychoazn posted in reply to my inquiry about Li-Ion batteries, that he has ordered a Lithium-Iron-Phosphate (LiFePO4) battery from Shorai, for his S2K. I followed his lead and did quite a bit of research, and I'm considering ordering the Shorai model LFX36A3-BS12, a big brother to the one that he ordered, that only weighs about 5 lb. Turns out that BatteryStuff.com carries them, and their rep assured me that it will crank a normal internal combustion engine just fine, and be compatible with the charging systems of normal cars. I am still checking questions like (1) can a LiFePO4 battery be safely jumped from a standard lead-acid battery, and (2) do they have terminal adapters. (On the latter, I could of course fab some adapters & solder them to my cables, but would rather not get into that.)

These LiFePO4 batteries cost > $300, about double the cost of a good AGM lead-acid battery, triple cost of a cheapie, but they claim longer life span.

Wondering if anyone else has tried this or other LiFePO4 batteries on their S2K.

20-lb weight savings = free hp ))

Bob

spunkysandoval

Do you have any pictures of the Life battery?

I use a lot of LIPO batteries for my RC cars, but these require constant balancing and special chargers. The life batteries also require balancing, but I'm assuming the battery this company sells has an internal balancing device.

What are the specs on the battery? CCA? WA?

jbird0007

I first heard about LiFe batteries when they were introduced to the RC market about a year ago. From what I understand, they are more stable than Lipo, dont require balancing, and provide a longer cycle life. I havent checked the prices of these batteries for automotive tho.

if you're looking for lightweight, performance automotive batteries, check out this company Braille batteries. when I was on the Formula SAE hybrid team at Umass Lowell, we were planning on using 8 of these batteries to supplement our gas/electric drivetrain.

braille makes plenty of batteries, theyre about a third the size of a normal car battery, and boast the same, if not better amperage and voltage of lead acid batteries. the prices are a bit high (around $400 i think), and come in carbon fiber casing etc and weigh about 2.5 lbs. they even have a 12v lithium battery that weighs 1 lb!

heres the website

http://www.braillebattery.com/index.php/batteries/ml7s/

Sobe_Death

This. If it doesn't have an internal balancing circuit then the life of the pack will be reduced significantly.

oldtrlrnr

The Shorai model LFX36A3-BS12 LiFePO4 battery is rated 36 AH, same as our oem battery; and 540 CCA, vs 410 of our oem battery. It weighs ~ 5 lb vs 25 lb for our oem battery. Click here for link to specs & photos of this battery.

I have been told by a rep at BatteryStuff.com the following:
- These batteries are designed for starting duty in vehicles with internal combustion engines (though mostly jet skis, snowmobiles, etc).
- These batteries can be jumped safely from a standard, lead-acid battery.
- These batteries do have a basic BMS (battery mgmt system), but it acts more like a protection system than a cell balancer. Shorai does make a charger that charges individual cells via a port on the battery. Apparently this gives at least charge-mode cell balancing.
- There are terminal adapters to connect standard cables to these batteries.

I'm about sstisfied and ready to take the plunge.

Bob

oldtrlrnr

jbird0007, I browsed the Braille site; found they make lots of batteries. Most of them are AGM lead-acid, and the lightest of those have low AH ratings, a direct function of their small size & relatively light weight. Lead-acid technology has a rather fixed energy:weight ratio, with only small variations in efficiency due to the level of lead purity they use, eg AGM vs wet cell. I found that Braille also make a "lithium" battery, but I couldn't find whether it is Li-Ion or LiFePO4 or some other variant. I ran across a thread the other day where someone mentioned that some of the Braille batteries are made by some other manufacturer (Deka?), and rebadged with higher price. I didn't check prices of any of the Braille batteries, but $400 sounds high - the Shorai model LFX36A3-BS12 LiFePO4 battery is listed at $315 on BatteryStuff.com.

- Bob

IntegraR0064

Thanks for posting, if you get the battery I definitely want to hear how it works out.

oldtrlrnr

I'm ordering the battery, and a terminal adapter kit ($7.00) today. The tech rep at BatteryStuff.com told me that a battery minder/conditioner is not really necessary for these LiFePO4 batteries, apparently b/c they don't sulfate like lead-acid batteries. I appreciated him not over-selling me - enhances credibility of all his advice.

BTW I found out that the 2010 Porsche 911's use a lithium-ion battery.

I will post a report on this battery after I've installed it and gotten a week or two of experience with it.

- Bob

psychoazn

psychoazn checking in here. First off, an apology for not following up on the other thread. The new s2ki doesn't have a "mys2ki" so its hard to keep track of where I've posted.

Simply put, knowing the specs, and holding it in person are two completely different things. When doing my initial research, I read several posts saying that when they got their box, they thought they had been jacked. Knowing that, I was expecting a light box, but when I got my box, I was like.... WTF empty box?!?

I purchased the 27AH battery, and it starts the car like a champ. We won't know long term results, but if I get 5 years out of this thing, I'll be more than happy.

Quick clarification for everyone, this is a Lithium-Iron-Phosphate battery, not a Lithium-Ion. The technology is less than 15 years old, and consumer batteries have barely been on the market for a few years now. Oldtrlrnr and I are getting the 2nd batch of batteries produced by Shorai.




This battery does have its own properties that defy those of "typical" batteries. The internal discharge rate is SUPER low, and as a result, this battery has a superbly long shelf life.

In cold weather, the battery has less CCA. However, turning on your headlights will put enough of a drain on the battery to warm it up internally, and it will be able to start the car after a brief period (Motorcycles are reporting less than 30 seconds). Alternatively you COULD just crank; cold weather users have reported that each successive crank gets stronger as the battery warms up.

The battery should not be trickle charged unless you purchase the shorai specific charger. However, at normal charge levels, it is perfectly usable with our regular charging system.

A lead-acid battery needs roughly 75% of its charge to maintain its relative CCA rating. The Shorai on the other hand will retain its CCA rating at even a ~25% charge level.



As you can tell, so far, I love this thing.

-Mike

oldtrlrnr

I received my Shorai LiFePO4 battery yesterday, and installed it & took the car out for a drive, running a few errands, with several stops. The battery starts my engine fine, stronger than the original lead-acid battery. I got the 36AH model, LFX36A3-BS12. It weighs ~ 5 lb! 20 lb weight savings = free HP

Installation was very easy. The battery comes with L brackets that bolt to the terminals. I forgot to order the post terminal adapter kit, but found I didn't need it. I just squished the round terminal ends on my cables flattening them out, and bolted them to the L brackets with a couple of 6mm bolts (slightly longer than the ones that came with the battery). Should I need to go back to a lead-acid battery with post terminals, I'll be able to reshape my cable terminals easily. The battery comes in a box padded by several sections of adhesive-backed foam. These are specifically intended to be used to shim the battery to fit the standard battery tray. I used one sheet of the foam on the bottom of the battery, and one piece trimmed to line the retaining bracket. This way I was able to use the stock retainer rods & bracket, for a secure, insulated tie-down. Very easy. You can see the battery & installation in the attached photos.

I'll report again when I've had a few months' use with this lightweight battery.

Bob



[attachment=4467:Shorai & oem batteries.JPG][attachment=4468:Shorai battery installed 2.JPG][attachment=4469:Shorai battery installed overhead view.JPG][attachment=4466:Shorai battery.JPG]