How to recharge Apple lithium

How to recharge Apple lithium-ion (Li-ion) batteries of macOS devices? Three questions:

1. When is it recommended to recharge Apple lithium-ion (Li-ion) batteries of macOS devices? When they are at 50% charge?

2. Is it bad for battery life to leave such devices connected to mains (charging) when fully charged (for instance, overnight)?

3. Which is the best charge level to store such devices shutdown for long periods of time (months or years) without being used? 100% charge?

Thanks.

最後更新：2017-08-24 15:06:32