Which power source Surface 3 use while charging?

[Windows Central Question]

Someone on the internet says that we shouldn't using device while charging it because charge and discharge at sametime will harm the battery.
So I want to know which type of power source, battery or AC directly from charger, does Surface 3 use while I charge it? If it use AC directly from charger, I think it will not affect the battery life.

 

[noersetiawan]

Not sure but I think, unlike laptops, most phone and tablet draws power from battery as the AC supply isn't enough to supply the power, notice most are using USB adapter, but this (charge and discharge) will not hurt the battery. It's the heat that is damaging the battery. So spreadsheets and YouTube is fine, 3D gaming, or any task that your CPU can't handle without generating too much heat, is not so.. If it's too hot for your hand, it's too hot for the battery. Anyway, do not worry about it.