3 picks with specs, filters and a calculator to find the right size.
A battery switch shuts off power when you leave the boat and lets you pick a battery. A charging relay lets the outboard charge two batteries without the electronics ever draining the starting battery.
A compact on/off switch that fits almost anywhere. Use one to shut off a trolling motor bank or house battery when the boat sits.
Best for: Disconnecting a trolling motor or accessory battery.
Check price on Amazon (paid link) Specs from bluesea.comThe classic Off/1/All/2 selector on many bass and fishing boats. Start on one battery, then switch to the other. Never turn it through Off with the engine running.
Best for: Replacing the selector on a two-battery boat.
Check price on Amazon (paid link) Specs from westmarine.comA switch plus an automatic charging relay. The outboard charges both batteries, the starting battery is kept separate from the electronics, and one knob shuts everything off.
Best for: Adding a house battery for electronics to a boat with one starting battery.
Check price on Amazon (paid link) Specs from defender.comNo products match those filters. Try clearing one.
Pictures are our own illustrations, not photos of the actual products. Specs come from the manufacturer or retailer listing linked on each card and were checked in October 2026. Models and prices change, so confirm details on the listing before you buy. As an Amazon Associate I earn from qualifying purchases.