Relays, Combiners & Disconnects
These are the parts of a marine electrical system that switch themselves. A relay opens or closes a circuit on a signal rather than a hand on a knob, a combiner ties two banks together while the alternator is charging and separates them when it stops, and a low voltage disconnect drops the load before a battery discharges far enough to damage it. All three do the job continuously, without anyone watching. For the manual equivalents see Battery Switches.
What to Look for in a Relay or Combiner
Match the continuous amp rating to the load, not the peak, since a relay that runs near its limit gets hot and shortens its own life. Check the voltage range too: a unit rated 6 to 35 VDC covers 12V and 24V systems, while 48V banks need hardware built for them. Decide how much control you want. Bluetooth models let you set cutoff and reconnect voltages from a phone, programmable modules hold several functions in one housing, and a fixed ACR simply does one thing reliably. Connector type matters at install time, with NMEA 2000 and DT plugs going in faster than loose wiring but committing you to that system.
What This Category Covers
Victron BatteryProtect low voltage disconnects in standard and Smart Bluetooth versions from 100A to 220A, Cyrix intelligent combiners and load relays, the Egis XD Series in single, dual and triple configurations with relay, ACR and mechanical switch combinations, Egis time delay relays, and Newmar emergency backup relay chargers. Ratings run from 80A to 230A across 12V, 24V and 48V systems.
Complete Your Electrical System
Diode and FET isolators that split alternator output across banks are in Battery Isolators & Charging Relays. Manual selector and disconnect switches are in Battery Switches, and panel-mounted toggles and rockers in Marine Electrical Switches. Protect each circuit with a breaker from Marine Circuit Breakers, land the heavy cable on a bar from Bus Bars & Power Distribution, and watch what the bank is actually doing with a monitor from Battery Monitoring.
Browse our complete selection of marine relays, combiners and disconnects at CritPro.