[Egdhifh]

It does, if the battery is 100% no more charging current goes in, so charging stops.

But the key point is that the battery will drop to 99% very quickly and on it's own because no battery can keep the energy in perfectly. So it's recharged for the missing 1% over and over again which causes the damage.

Unless some smart charging logic prevents that, see other comments here.

Edit: typo

[brandall10]

It's not just this, it's literally bad to keep a lithium ion battery in a high voltage state, period. Simply taking a battery out and leaving it on the shelf in a high voltage state, otherwise unused, harms it.

[Egdhifh]

Agree, not sure why though. Because the isolation degrades because of electrons breaking through it?

However, keeping "a lot" of energy in the battery is kind of the purpose, no one is using 50% max to increase battery life. But I guess most damage increases exponentially with energy stored, so charging it from 95% to 100% will damage it a lot more to than charging it from 90% to 95%.