Mine stays plugged in so that the fridge stays cold and I have 120v there when I need it, except that I turn OFF the breaker on the 120v to 12v charger to the battery, and the battery is maintained through my solar panels, which do a much better job of topping-off and "floating", as necessary.
Be Safe, and Everyone Goes a Home,
2014 RAM Laramie 2500 w/6.7L Cummins Diesel and Automated Safety Hitch
2016 377RLBH Jayco North Point
300W of Suntech Solar w/Rogue MPPT Controller & Xantrex 2000W PSW Inverter