RV A/C Unit On Truck

Its a heat pump, just like your ac, theres an indoor and an outdoor unit, phase changing gas to liquid refrigerant runs through som pipes

 

Charging a lithium bank on a vehicle is done by a DC to DC charger which regulates current. Mine is adjustable and I charge at about 40a which usually only takes a few hours of driving time during the day. I have this same setup in 3 vehicles. All alternators are fine and 2 of them are the OEM 165 amps, including my rig. You don't just hook up lithium batteries off your chassis batteries and call it good.

I do recommend a stronger alternator when/if it needs replacing. I'm going for a 220a sooner or later probably which is a common one for my truck, if I'm remembering the size right.