Victron ArgoFET Battery Isolator

Similarly to diode battery isolators, FET isolators allow simultaneous charging of two or more batteries from one alternator (or a single output battery charger), without connecting the batteries together. In contrast with diode battery isolators, FET isolators have virtually no voltage loss. Voltage drop is less than 0.02 volt at low current and averages 0.1 volt at higher currents.

Some alternators need DC voltage on the B+ output to start charging. Obviously, DC will be present when the alternator is directly connected to a battery. Inserting a Diode or FET splitter will however prevent any return voltage/current from the batteries to the B+, and the alternator will not start. The new Argofet isolators have a special current limited energize input that will power the B+ when the engine run/stop switch is closed.