Battery Isolators

Hey guys I'm new here. Building an 85 M1009. I'm hoping that this is the right place to post this. I have a phantom leak. I want to keep the 24/12 set up and add a third battery to run the accessories. My question is, what is the best way to hook up a 3rd battery and isolate my 2x12v batteries for starting. I'd like to be able to shut it all off from the cab and use the 3rd battery to boost my primary batteries if they go flat. I hope this makes sense.

Sounds like an issue because I'm assuming you would be tying your 3rd batt in parallel with batt #1 on the cucv. In this scenario you would be able to charge batt #3 no problem then isolate it to run accessories. Issue will come up if you have dead starting batts, batt #3 will not provide you any assistance in the 24v circuit.

Look at the Blue Sea Systems add a battery kit. I use solar to charge my camper battery, but have it wired so that I can tie it into the front two if need be (like really cold starts). It also allows the truck charging system to charge the camper battery as well. Really happy with it, but be sure to wire it with the proper gauge.

http://www.bluesea.com/products/7650/Add-A-Battery_Kit_-_120A