Victron ARG100201020 Argofet 100 Amp Battery Isolator for two batteries

Like diode battery isolators, FET isolators allow simultaneous charging of two or more batteries from one alternator without connecting the batteries together. So discharging the accessory battery will not result in also discharging the starter battery. This isolator allows simultaneous charging of three battery banks. 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. When using ARGO FET Battery Isolators, there is no need to also increase the output voltage of the alternator.Some alternators require a B+ voltage at a terminal in order to start charging and this isolator has a special dedicated connection for that purpose. Battery isolators may not be the best way to go if you are designing a new system, but if you want to upgrade an existing system and don't wish to do a total rewiring job then using this Argofet low loss isolator is a practical and economical way to go.