ToothDoc

What do you guys think of my 3.5 pound IS-F battery? It runs great and weighs a LOT less than stock. I just took off the engine cover and some of the engine bay plastic (not the ones with the rubber seals). The plastic removal weighs more than the battery!

I got the batteries on EBAY for $138, some solder, some wiring, some post adapters, and some time. For about $175, I have a 13.2 volt (12.9 volt is standard SLA battery) that has 11.5 amp hour capacity with ZERO peukert effect and almost NO energy drain. I took it to the local battery shop and the CCA is around 400 amps. According to the A123, they're rated at 60 amps per pack and there is 5 packs so 300 amps continuous and up to 120 amps peak/pack so 600 amps peak for 10 seconds. I tested the car with a DC ammeter and it seems to peak out around 400-500 amps during a cold start for about 1 second and then about 150 amps or so during the next couple of seconds so I'm well under the peak limitations of the batteries. The batteries peak at 14.4 volts but the voltage regulator of the alternator is 13.75 volts so I'll never overcharge the batteries.

I'm hoping to shave off a tenth at the strip this fall... Maybe take Caymandive's 12.38 (of course he'll go with with the Joe Z and maybe hit 12.2s)

chrisburke

interesting. is the CCA going to be ok on those cold days? but it looks COOL..nice work..

ToothDoc

I'm actually just in the testing phase for now. These cells are rated for -20 degrees Celsius so they should work pretty well in the cold. I'm temporarily driving around with a 2 pound booster pack (3 packs of 4 cells) which ALONE can start up the car. Eventually, I might end up with a 10 pack of 4 cells which will more than surpass CCA of most aftermarket 12 volts batteries. 10 packs will also pack 23 amp hours which is much less than standard batteries but at 8 pounds, it'll have plenty of starting juice. One thing is that lead acids have constant drain on them so they lose charge all the time. Lithium Ions don't lose very much - 6 months later, you'll still have 90% charge (well, not in a car - the car constantly drains power) whereas in the lead acid, you'll have a dead battery. In addition, lead acids become less and less efficient the higher the amp draw while these lithiums give almost the full capacity even at high amp draws.

I'm actually thinking of draining out the acid and all the plates in the car battery and using the 12 volt CASE so I can use all stock mounting brackets and stuff.

Another advantage of lithium ion is that they have a much HIGHER cycle life - over 2000 full discharge/charge cycles vs. 200 of lead acid so this battery will outlive the car.

chrisburke

that is cleaver.. i would get a stock batter too and fit it in it. i like it.. keep us posted..

MicaISF

great job on your battery.

i have researched into lithium ion batt options over the past year. i was under the impression that lithium ions do not provide enough CCA, guess i was wrong.

which lithium ion batt do you have? i believe lithium iron phosphate is more suitable for automotive use because of better tolerance to heat and less tendency to overheat. another issue is you might want to install a charging controller to avoid overcharging which can kill the batteries.

check out this link for some batts.

http://www.batteryspace.com/lifepo42...oxwithpcb.aspx

http://www.batteryspace.com/lifepo4b...ongerlife.aspx

stick

I laughed thinking this was a joke! Can you run these in your E-MAXX?

If everything works out, you should build these and sell them. Seems like a good track battery.

ToothDoc

Generally Lithium Ions have too much internal resistance, but A123 had developed some super small particle stuff "nanotechnology" a couple of years ago that allow their lithium to discharge at over 30C (30 x their capacity in amperage) which is an order of magnitude greater in discharge rate than standard lithium iron phosphate cells AKA LiFePO4 cells. I have considered using lithium polymer for years - but the problem of possible fire, over discharge, over charge, made me give that up - if I did use Lithium Polymer, I'd have a 2 1/2 pound pack instead of a 4 pound pack.

By the way, they use the A123 LiFePO4 cells in the Killacycle drag electric motorcycle which does 7's and 170 mph in the 1/4. These are also the cells in the Tesla and also the plug-in hybrid Prius conversion kits.

ToothDoc

Yes, you could use it in your E-Maxx, but the cells are 50% longer than standard sub C so if you made a pack, it wouldn't fit.


Also, I heard just recently that you can buy a Porsche GT3 RS with a track use Lithium Ion battery! LOL - I wonder how much they charge?

In addition, they already sell Lithium Ion track batteries - I forget the link, but they are asking 1300$ for it! They used to use a bunch of even smaller cells - but they might have switched over the A123 just recently.

caymandive

iTrader: (2)

Very cool Tooth! I had been watching your updates on facebook and was waiting to see your official post and picture.

IS-Fly168

iTrader: (1)

Man!!! all that work,, can I say Honda Fit battery? maybe not as light but its still a car battery that should work ok in our F.....

n0th1ng

iTrader: (9)

this is kinda cool... are you thinkin of using this for the tracks only?

CircuitMS

iTrader: (51)

Interesting....

ToothDoc

I haven't turned the car on since 30 hours ago. The voltage is now at 13.1 volts. I won't drive it tomorrow either. I think I'll turn it on about Thursday or Friday and see what happens. I have a video of me starting it up, but it's uneventful - just sounds like a normal startup.

ToothDoc

I also did some research and just found out that the Optima Red top starting batteries have a capacity of 40-50 amp hours (c/20 rate). The LiFePO4 pack I have right now is 12 amp hour so it's got about 1/4 the capacity.

ToothDoc

It definitely could be used for tracks, but I'm hoping to make it into a permanent part of my IS-F.