Starting Battery wiring

[TooBusy]

I recently purchased a new boat and have got things rigged up about the way I like, but I have a question in regards to starting batteries. I have two locaters, and the radio running off of the starting batteries as well as the bilge pump, livewell etc., as originally wired by the manufacturer. I tend to fish fairly lengthy periods without running the main motor (150 hp Yamaha 4-stroke) and I am concerned about running the battery down and get myself in a pickle. I would like to add a second starting battery, wired in parallel to increase my reserve capacity, but I don't know how my charging system from the motor will react. Have you seen this done? Do I have to separate the batteries? Suggestions would be appreciated.

[Surface Tension]

I'd keep them separate and buy a Deep Cycle battery for the livewell, radio, and electronics.

If you wanted two batteries and some type of management over them then a switch like Quest that allows you the options of: Off- battery 1- battery 2- or Both. In your case I really don't see a need for the switch though and would keep the starting battery dedicated to the outboard.

[BobT]

If you're concerned about running the starting battery down I agree with SurfaceTension. To run the electronics you're talking about would not require a very big battery so you can save cost and weight by using a smaller one. If you have an electric trolling motor, run that on its own battery too (the largest you can afford) otherwise it may interfere with your electronics.

[jeffreyd]

buy a battery isolator, put it between the two batteries, all electronics on second or isolated battery starter on first battery or however you choose. this way when your electronics one is low it wont rob the power from the start one but will charge both when engine or charger is hooked up to starter battery. used them in fire trucks for many years.

[TooBusy]

Thanks for the information. After doing a bit more research based upon your replies, I am going to go with the battery isolator. Thanks again!

[BobT]

One thing. Don't rely on your outboard to maintain your battery charge. Not that it can't but typically we don't run our outboards long enough to recharge batteries properly. Just something to keep in mind.