Originally Posted by
cyccommute
The 3800 is obviously the mAh capacity of the battery. The 47 W is probably watt-hour rating which is the number of watts the battery can put out in an hour but Wh aren't used that much.
Except that 3800mAh at 13.2V is 50Wh. Sounds like a max power draw, which you don't need to worry about, because any rechargeable battery can source 4A.
So any 13.2V battery should work fine. Higher capacity (mAh, Ah, Wh) just means longer runtime and probably a larger and heavier battery.