Boat mechanics or parts dealers are able to provide you with an isolator, but equally important would be a diagram of where the alternator wire comes off the main motor. They are also more than willing to help, especially if you purchase your isolator from them. Here is a diagram of a typical installation. The following picture shows the actual unit installed in a boat. The single post in the middle secures the wire from the alternator. The other two wires run to the starter battery and the deep cycle battery positive post respectively.
We are an Amazon Affiliate. If you purchase a product we recommend or another product while on Amazon, we may receive a small commission. Our staff recommends items that we have personally owned, used/tested, researched or we have fished with trusted anglers who recommend them. These products will not cost you any more than what is posted.
As you add accessories, you may run the risk of drawing too much power from your starter battery, particularly if you are not running your main motor for extended periods, resulting in the alternator not keeping your starter battery charged. This is the time to begin to think about adding an additional deep cycle battery for your accessories. You could also add a second on board 2 bank battery charging system, or consider this isolator as a viable option.