We all know that devices can have their batteries weaken over time if you leave them charging for too long. Why does that happen and why can’t our devices just stop taking in power / cut off right when it’s full?

Question

On my own phone there’s a function where it can stop charging at 95% to protect the battery health. Why can’t it do this at 99.99% and present it as 100%? It would be unnoticeable to users and would prevent the overcharge issue, right?

In: Technology

Answer 1

It’s not because of charging, it’s because of sitting at full. For example, for Teslas you can schedule your departure, and it will start charging to full just when it expects it to be complete by departure time. So it doesn’t sit all night on 100%, but when you get into car it just reaches it, so it doesn’t sit on it for too long. If you limit your max charge to like 80% or the best 50%, then you can be plugged indefinitely and everything runs on power from charger. So battery is only getting wear through time (aging) and holding charge (the farther from 50%, the worse it gets). As a customer, if you want, for most devices you can put a limit and that’s as far as you should think about it.