Battery Combiner 100
The Combiner 100 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.
This combiner is suitable for installations with alternators up to 100 amps with one battery in each bank. Larger installations should consider using the 200 Amp model.