On the need to periodically discharge LiIon batteries

[Fallingwater]

The general advice on how to treat LiIon cells is "charge them whenever they need it, but run 'em flat once every 20-30 discharges to reset the battery meter".

As far as I understand, LiIon battery meters work by measuring the voltage. A LiIon cell's voltage goes from 4.2 when it's fully charged to about 3 when it's completely discharged (the cutout is likely to engage before it gets that low though). Measure the voltage and hey presto, you have the charge level.

So why should they be reset? Do they not always measure the same charge level at the same voltage?

 

[SilverFox]

Hello Fallingwater,

The "general advice" refers to the Li-Ion cells put together into a battery pack for a computer (or other device) that utilizes a battery meter. The battery meter is what needs to be reset, not the batteries themselves.

This confusion of the battery meter is caused by voltage fluctuations caused by temperature differences during use. Also, the cell voltage changes with age.

Tom