Li-ion battery charging is a big topic. Some dangers involved if you mix and match chargers. Usually there is a smart charger in the original purchase. If you substitute a dumb one, you'd better know your battery's voltage state, acceptable charge rate, charger's actual rate and voltage, and then time the charge or check the battery voltage as you progress.If you're using an non-original equipment smart charger, it may or may not be smart enough to handle this for you.Some people get lucky mixing and matching, don't seem to have problems, others destroy the battery, or worse.EDIT: I should add, a lot depends on the OEM wall wart type. If it's just a simple DC supply and all the necessary charge monitoring and filtering circuitry is in the slate, then you have greater flexibility in what you use for the "charger." It's really not a charger in that case, just a raw DC supply. Maybe that's what the apad uses... still waiting for mine.