It’s true that Keeping Your Laptop Plugged in All the Time Will Kill Its Battery Faster. However, there is a catch with the following assertion:
Cadex Electronics CEO Isidor Buchmann told WIRED that ideally everyone would charge their batteries to 80 percent then let them drain to about 40 percent. This will prolong the life of your battery — in some cases by as much as four times.
This is wrong. There is no need to charge the battery to 80% just to discharge it! Some smart manufacturers keep laptop batteries charged at 40% — so ideally they should be kept at this level as much as possible!
The compromise made by Lenovo’s Energy Management tool for the “Best battery health” mode is this one:
- it never allows the battery to be charged more than 50%
- when the battery goes under 45%, it starts charging it (to no more than 50%)
A number of people commenting to the linked article — even some Lenovo users — keep talking about charging to 60% or 80%. It’s all bullshit. To maximize its life, keep it between 40% and 50% — except for when you really need the longest possible runtime, so you have no choice but to fully charge it.
LATE EDIT: Samsung has a Battery Life Extender that caps the charging to 80%. They are fans of the 80% thing — I prefer the 50% one.