Thinkpads Forum

I have a spare battery for my T23 which hasn't been used much.

When I leave this spare out of the laptop, should I leave it charged or discharged?

For short term storage (a couple days) I'd say leave it charged. For long term storage, I've read that 40% or so is best.

Lol yeah one of those few times when the right answer is actually exactly in the middle

Common wisdom says 40%. My guess for the reasoning is that discharged is better, but since they lose charge constantly even without use, and lithium ions get trashed if they ever go to 0%, 40% is "safe."

You can never over charge your battery for storage. Your stored battery will however, if it louses all it's charge, be either damaged or ruined. There is a very good reason that all manufactures ship their batteries fully charged.

jmt wrote:You can never over charge your battery for storage. Your stored battery will however, if it louses all it's charge, be either damaged or ruined. There is a very good reason that all manufactures ship their batteries fully charged.

That's not true ...

Li-ion batteries storage table:

Temp ==== charged 40% ====== charged 100%
0° C ==== 98% after one year == 94% after one year
25° C ==== 96% after one year == 85% after one year
40° C ==== 85% after one year == 65% after one year
60° C ==== 75% after one year == 60% aftre three months

The recommended is 40% and temperature between 0-10 centigrades. But you can store your battery 40% charged and in the hall temperature 25C without any problem.

0% or 100% is the worst you can choose.

I charge mine to 40 percent and put it in fridge in a ziplock bag (prevent condensation when rewarming)