that everyone is talking about but still a combiner. It's a much better way to manage batteries then any other way I'm familiar with. I installed a push button switch that energizes the combiner and closes the contactor in an emergency to start the engine. If my start battery fails to have enough power to start the engine I can push and hold down a button that closes the combiner while I'm starting the engine to give the starter a better boost off of the house batteries. Just something you might want to think about.