In RV park. Now have car to drive. Disconnect RV battery?

I would think it would be better to trickle charge your truck start battery while sitting for long periods.

This would be a great application for one of those smaller wattage solar panels (AMAZON). Even on cloudy days and in the shade you should get an amp or so into the start battery during high Sun each day.

But since you will have shore power power available to you 24/7 the far best gaurenteed solution is to just plug-in a low output trickle charger... Something in the 12V-2AMP rating... Have to watch the 12V receptacles on most of the vhicles now that don't stay HOT with the ignition key OFF. Be sure to find one that stays ON all the the time if you get one of the trickle chargers that have the 12V plug on them.

My OFF-ROAD JEEP used to sit for weeks alot and one of those solar panels that lays just inside the windshield area on the dash was the perfect solution for me to keep the Jeep start battery going strong. I just plugged the solar panel into a always HOT 12V plug on the Jeep dash.

Batteries love to have a float charge going all the time... One caution I would think is not have more than 13.2VDC feeding the float mode to keep the possibility of boiling out fluids down to nothing...

Also disconnecting the NEGATIVE battery terminal on the truck start battery is something I am not in favor of doing on my trucks here while sitting. Too many electronic things are still running to keep the truck computers set correctly. They always say they will reset themselves after being disconnected but I would not chance that. This is just me - but having to go the dealership to have them reset your computers at a minimum of $90-$100 cost for a five minute job on their computer just seems out of line haha...

Just some tid-bits from me here...
Roy Ken

1. Are you camping with hookups, (electric) ?
If so, you don't have to do anything, the converter that charges your house batteries, should also be charging your chassis battery, (at least mine does).

Thank you.

Plug the battery tender into the 15 amp outlet on the pedestal or an external one on the coach. It will keep the coach battery(s) up without overcharging.

I'd take the negative battery cable off.

Bill