Large Tesla Battery

John & Angela wrote:

2oldman wrote:

road-runner wrote:
Can the Li battery be run all the way down without shortening its life? And I wonder how good its life is, in terms of discharge cycles, compared to a golf cart battery?

No. Mfr says 80%. 3-5k cycles.

And further to this you can google a survey on how many deep cycles the average EV driver cycles their battery although i don't recall if it mentions how deep they cycle. Anyway on average users charge about 125 times per year. For us it's about 80 and we tend to recharge at the 35 to 40 percent point. We usually charge to arround 90 percent but on longer trips we charge to 100 percent the night before. One down side of charging to 100 percent is the reduced Regen braking you get at 100 percent. This is because there is no where for the power to go until the percentage of charge drops a bit. A curiosity of electric vehicles.

The fact most people won't cycle the battery anywhere near 80 percent on a regular basis is what allows GM to bet that the battery they are putting in their Bolt will be able to maintain 60 percent capacity at the 8 year mark. Time will say whether or not this costs them. As for charging to 100 percent, all lithium variants I've seen age deteriorate quite a bit faster if stored in a fully charged state. If you're not going to start using it right away probably best to only charge to 95 percent or so.

Regarding the question on cycle depth and battery life, none of the batteries I've seen the independent data on have been able to meet the criteria of still being able to reach 80 percent of original capacity after 2000 cycles of 80percent. That is of course on a bench in a controlled temperature environment. Like a lead based battery, depth of discharge, temperature and current rates for charge and discharge can have negative effects, but for the most part they aren't as pronounced as what you see with lead acid. It's not unreasonable to expect twice the cycle life out of a lithium based battery cycling through 80 percent as what you would get from a quality lead acid being cycled 50 percent. Unfortunately, like with any new technology real data is hard to come by, and user perceptions tend to be terrible.