Looking in other forums, I found info on compatible batteries.
Toshiba PDR-BT1, Fuji NP-80, and a Ricoh battery are identical in spec, and all work with the built in charger on the DC4800.
The Toshiba PDR-BT2 is a higher capacity battery (1300mah versus the 1100mah) than the battery supplied, and will provide longer battery life while shooting pictures.
Unfortunately, most places are out of stock on many of these batteries.
I heard there is an AC Delco equivalent that also works, but I don't know the model numbers.
I lucked out and found 2 PDR-BT2's on clearance last week at IGO.com for $20.00 each... They're sold out now..