A marine battery isolator is a device that helps to ensure that your boat’s batteries are properly charged and ready to use when you need them. It does this by allowing the Alternator to charge two or more batteries independently while preventing any discharge between them.
This is especially important in boats because it means that you can have a dedicated starting battery for the engine, and a separate deep cycle battery for accessories, like lights and the stereo.
Without an isolator, if your main battery were to run low, you might accidentally draw power from the starter battery and cause it to fail – leaving you stranded!
Most marine battery isolators are automatic, meaning they’ll sense when one of the batteries needs charging and will engage accordingly. Some also have manual controls so that you can override the system if needed.