Battery Combiner 600
The Combiner600 is a voltage-sensing relay which connects two batteries together when either is receiving a charge. When the charging ceases, the relay opens so that each battery operates independently. Supplemental battery banks can be added by using an additional combiner for each bank. You never have to worry about switching to "BOTH" when your engine is running and forgetting to switch back to save your starting battery from discharge when you stop.
Please note: This product is only recommended if you will have a dedicated house battery that will be charged automatically with a Combiner or Trollbridge.