Maximum possible file size and fastest charging speed?

[SammysHP]

Does it even use 5 W? Anyway, you can plug it into a 2000 W (5 V) supply and it will charge the same as with the 5 W supply. Li-ion batteries are charged with a CC/CV method meaning that first the current is limited by the charging controller until the maximum voltage (usually 4.2 V) is reached. Then it keeps that voltage until the current is low enough.