I don't drive my truck often due to high Diesel prices in CA.

I would like to float charge the batteries to maintain them and was wondering if one float charger hooked up to one battery (nothing disconnected) will maintain both batteries. or should I add one float charger to each battery?

 

They are in parallel, so hooking a charger on one will charge the other one.

 

the alternator charges them in parallel, I actually charged them seperatly for a while till I thought about it a little.