National Luna Battery Management System
This battery management system is designed to be installed in the vehicle to manage twin battery setups.
It has an intelligent solenoid that works by sensing the increased charge voltage on the main battery.
The solenoid will not allow a connection if the auxiliary battery has reverse polarity, is short circuited or there is no aux battery.
There is a twin digital display to show what both batteries are doing and you can manually link the two batteries when extra power is needed for a winch.
There is also a built in alarm for when either battery drops below 11.4v and will flash the bottom light.