There is room in the cab or in back of the hood section to build in a battery charger. A standard 2 bank marine charge is required. The advantage is that you do not have to take the batteries out of the engine to recharge them.
An 8 amp 2 bank (4 amps/bank) charger starts at $100
A 12 amp 2 bank (6 amps/bank) charger starts at $150