EV vs Light's LiIon Use

[jayflash]

One manufacturer of an electric vehicle claims the LiIon cells in the car are best discharged to about 20 - 25% capacity and then recharged, for maximum useful capacity/life of the cells.

They claim the total number of charge cycles is the main determining factor in the LiIon's life. They claim a partial charge equals a full charge and that topping off the cells is no better for life than deeper recharging.

Perhaps I'm mixing up my facts and forgetting SilverFox's info, but I thought LiIon cells for our lights were better topped off rather than more deeply discharged.

Sorry for going over old ground, but could someone bring me up to speed?

Thanks!

 

[Fallingwater]

They are. 30% isn't a deep discharge, but LiIons should still be topped off whenever possible.

 

[SilverFox]

Hello Jayflash,

You may find the article referenced in this post informative.

Tom

 

[bob_ninja]

I believe Prius uses 30%-80% range for NiMH
The new Volt and other EVs will use a similar range, perhaps 40%-90%
I think most EV makers are being conservative and not going below 30% because of the high cost of battery packs.

30% is not a deep discharge.

 

[bob_ninja]

Just happened to be reading an article:

To maximize the chances that the standard Prius battery pack will survive 10 years under any conceivable operating conditions, Toyota rigorously keeps the pack's state of charge—expressed as a percentage of the full-capacity charge—between 50 and 80 percent. Toyota does not disclose exact details, but some engineers say the band is even narrower under most operating circumstances.

EV article

 

[jayflash]

Thanks for the links and info. Do I correctly understand that shallow discharges are better than deeper discharge/recharge cycles? Also, keep the charge level to 4.1 or less, volts per cell, rather than 4.2 volts for maximum life? That and don't trickle or deep discharge LiIon or most other types of cells?

I know this info has been presented numerous times, but the supposed advice to more deeply discharge LiIons in an EV is better for maximum life had me wondering whether it was correct.

 

[bob_ninja]

It is wrong.
According to the posted data, neither extreme is good.
BTW, the Prius packs under that regime seem to last a very long time.