Yes, ElbyJ, you need to disconnect it between trips or arrange for some type of trickle charger, maintainer charge to be placed in the battery.
Most RV's have enough "parasitic" draws that it will kill a battery in a few days to a week from a full charge. Radio, circuit boards on the appliances, gas/smoke detectors, etc. To prevent their batteries from being dead all the time, many people install a
BATTERY CUTOFF SWITCH like one of the ones pictured.
Other options are leaving the trailer plugged into shore power or adding solar to keep it charged or hooking it up to a battery smart charger (3 stage). If using one of these, check the batteries water level once in a while (60-90 days) to make sure it don't boil dry.
Use this opportunity to decide if you want to get a bigger capacity battery that might extend the amount of time you can camp with power when not using shore power. If that's something you do, now's the opportunity to buy bigger or multiple batteries as you want to replace batteries as a system, together, not add a new one to old ones.
Hope all this helps. Good Luck!