It's worth pointing out that the B2B unit will not drain the starter battery, as it effectively relies on the surplus power of the alternator to charge the second battery, so you'll always have power to start your engine.

Having installed a B2B unit, then installing one of Sterling's Pro Budget battery chargers to the main starter battery, will give you dual battery charging capability. The mains battery charger will charge the starter batter, the the B2B unit will detect spare charging capacity, and use the spare capacity to charge the house/second battery. This set-up will also allow you to use 12 volt appliances whilst on hook-up.

The B2B is quite and advanced unit and although described in its simplist form above, its quite advanced. For a more in depth description of the B2B unit click here

Link to the Pro-Budget chargers