Collection: Battery Isolators

Keeping your starting battery separate from your house or trolling bank is a basic requirement for reliable time on the water, and the right isolator handles that passively without a switch to forget. The selection here spans diode-based and solid-state designs from Mastervolt, ProMariner, Samlex America, Analytic Systems, Newmar Power, and Sea-Dog, covering two-bank and three-bank configurations at amperage ratings from 120 to 250 amps. Mastervolt's Battery Mate IG series incorporates an integrated generator input, while ProMariner's ProIsoCharge line and the Analytic Systems ideal isolator address the voltage drop that conventional diode designs produce.

Before buying, confirm your alternator's rated output and whether you need two or three banks charged independently. Voltage compatibility matters, since most units here target 12V systems, though the Samlex 160A covers both 12V and 24V and the Analytic Systems 200A is rated to 40V. Check mounting space and terminal wire capacity, as higher-amperage units are physically larger. If minimizing voltage drop matters for your setup, the ideal diode and solid-state options here are worth a closer look.