(learn me) what do we think about Lithium batteries for racecars, street cars, etc?

alfadriver said:

WillG80 said:

Slippery said:

In reply to irish44j (Forum Supporter) :

Lithium is fine. Just make sure you disconnect from the car as they do not like to be discharged all the way. 

Being a racecar disconnecting is not. Big deal, otherwise look for one of the ones that have a safety turn off built in. It will shut itself off before completely discharging and you can override it once you are ready to use it. 

I thought one of the benefits of using Litium batteries vs Lead Acid is the ability to be discharged completely? At least that's what the camper crowds are preaching these days. They claim lead acid is only good for 50% max discharge before damage occurs. Is that not the case?

In a car, you rarely need to completely discharge a battery- so that's one thing. (for cars, CCA is more important than capacity for a car).

Until you lose an alternator on stage and you have two more stages and 30 miles of transit to do at night, anyway 

Oddly enough enthusiast cars are the worst for reserve capacity requirements.  RC is the how long in minutes the battery can supply 25 amps before it is too discharged, and I forget the exact figure for voltage, but figure that at about 2/3rd of the RC used up, the engine may not crank.  If a car has a 40ma parasitic draw when parked, then it generally works out to roughly being parked for two weeks before it may not start.  Batteries are USUALLY better than the RC, which has a fudge factor involved, but rarely driven cars are the worst for cycling the battery state of charge up and down.

In reply to Pete. (l33t FS) :

If you have a rarely-driven car, you need a solar panel on top of the car cover recharging it when it sits!

I've recently switched from a poweroad 440cca Lithium Iron Phosphate battery back to AGM. I had a reasonable run from the lithium, but after 3 years it just died over the course of a week. Just went to start the car and it was dead. I thought Id left the master switch on, but nope... so there was zero parasitic drain involved. Even fully charged to 14.4v on the trickle charger it won't crank the car now. Battery tester reports about 50cca. All cells are at 3.6v each so the BMS is working. It has never been drained and the car charges at 14.0v

I've gone back to an AGM one, its 20AH. Battery tester reports about 450cca (the manufacturer doesnt report a cca for this battery). I did that, and accepted the weight penalty of about 5kg, because the lithium battery is over 3x the price of the AGM, and at only 3 years life I find that a bit unacceptable on the cost to benefit ratio. I hear many stories of AGM lasting a long time, around ten years. 

The other aspect for us to consider, is all these lithium batteries report being able to deliver good cranking amps... but is it good for them? I've not heard any/many success stories about people running these long term in cars. In bikes and quads expect they would last better but in a car we are running them to the extent of their abilities every time we start, maybe that has been a contributing factor into mine, and others only lasting 3 years. 

In reply to Morrisman1 :

No. Huge discharges out of lithiums without pre-heating or conditioning before hand hurts them more. It's why Teslas say, that to get the longest life out of the battery only supercharge when you absolutely have to.

This COULD be done for a car battery to start it, but it would require some kind of timer and heater circuit ($) and will require more cells to deal with that drain ($) as well as for you to turn a key and wait as if it's a diesel glow plug- albiet one that takes much longer to warm up to fire. 

So I went round and round on this as well.

For the Datsun I use a Grp 51 battery; going to a lithium battery would save 22lbs. Realistically even in a car as light as mine (1802 w/driver) you are not going to notice 22lbs.........it represents a 1.2% weight savings. 

Given the extra care and feeding I didn't think it was enough of a gain.

In reply to Tom1200 :

Yeah, something that crossed my mind is that sometimes I take passengers for rides, and seldom ever are those times any slower than when the car is empty.