Sometimes you need to disconnect...
Towed Battery Disconnect switch is designed to cut-off power flowing to the battery to avoid unauthorized use of your vehicle or unwanted battery consumption when not used for long periods of time. It is ideal for towed vehicles where the manufacturer required battery disconnect for flat towing. Also ideal for cars, boats, trucks, RVs and more. For use with Top-Post Style lead-acid batteries (6, 12 or 24 VDC). Connects to negative battery terminal only. Rated at 500 ampere surge and 125 ampere continuous at 12 volts. Easy to use. Battery is disconnected by unscrewing the green knob and reconnected by tightening the knob. It is made from a high-conductivity zinc alloy and brass plated to prevent corrosion.
Battery Disconnect Installation Video