Victron Argofet 100-3 100A FET battery isolator for 3 batteries

Victron Argofet 100-3 Three batteries 100A

Similar to isolation diodes, FET isolators allow two or more batteries to be charged simultaneously by an alternator or charger connection without connecting the batteries to each other. Discharging the onboard electrical system battery does not cause the starter battery to discharge at the same time.

Unlike isolation diodes, FET isolators cause virtually no voltage drop. The voltage drop is less than 0.02 volts at low currents and only 0.1 volts at higher currents.

With ARGO FET battery isolation, no voltage increase is required. However, short cable lengths and sufficient cross-sections should be ensured.

For example:
A 100 A current causes a voltage drop of 0.26 volts with a 10 m cable length and a 50 mm² cable cross-section. With a 5 m cable and 10 mm², a 50 A current causes a voltage drop of 0.35 volts!

Alternator starting excitation
Some alternator types require DC voltage at the B+ terminal for starting excitation. On the one hand, there is a direct cable connection between the battery and the alternator. On the other hand, however, the isolation diode prevents reverse current flow, so the alternator does not start. The new Argofet battery isolator has a special current-limited connection for starting excitation when the alternator is started.