Charging Modules give you the ability to charge your 24-volt trolling motor battery bank from your 12-volt engine charging system. Once the engine has started the unit allows the engine starting battery to be charged first. Once the engine starting battery has reached 13.7 volts the unit will engage and charge battery A in the trolling bank for one minute. In the 24-volt system, it will then disengage and charge battery B for one minute. It will then transfer back to battery A. The unit will continue to repeat this process while the engine is running. When the engine is stopped and the residual voltage drops below 12.7 volts the unit will disengage leaving the trolling bank isolated from the starting bank. The Trolling Bank Voltage Sensitive Charging Module will increase battery life and allow you to fish longer. Every time you use your outboard, you will be charging your batteries. 10-gauge wire recommended. Eliminate the heavy on-board charger from your boat and gain speed.