How is the battery managed in a mac/laptop/iOS device?

[rodion15]

Anyone can help me find resources explaining how the battery is managed in a laptop/ smartphone?. I mean, when does the battery charge?, when the motherboard/logic board is being powered by the battery or the power adapter.
I guess the workings are similar in all portable computers and smartphones. It's hard finding resources explaining this and I'd like a lot to know how this works.