12V source

[Grippy]

Originally Posted by Hayesio

What's wrong with just using a voltage sensitive relay (aka VSR aka dual battery isolator) like 98% of all other dual battery systems in the world? $70 bucks on ebay, no triggers, no extra wiring, simple and very reliable.

I could do that but silly me already bought the continuous duty solenoid . Haha, no more eBay after a few scotches
If I can't work it out easily I'll get a VSR

[Hayesio]

You could put the solenoid you purchased in series with a VSR and wire a cabin switch to activate it. This will allow you to totally isolate the aux battery when you don't need it. This would significantly reduce the cycling of the aux battery giving it much better life.

[fester]

Originally Posted by Hayesio

You could put the solenoid you purchased in series with a VSR and wire a cabin switch to activate it. This will allow you to totally isolate the aux battery when you don't need it. This would significantly reduce the cycling of the aux battery giving it much better life.

Now we are going backwards even further. Why would you waste your money buying a VSR then adding a switch at more cost and more time with unnecessary wiring to have to "manage" the system manually. If you are going to throw any more money at this project just bite the bullet and put in a controller like the Redarc and let it do it's think totally automatically.

If you are going to use a switch then wire it to the existing solenoid and just turn it on and off manually BUT do not forget to do it correctly all the time or you'll wake up one morning with a flat starter battery or worse hot beer.

[Hayesio]

The reason you would put them in series like this is to reduce cycling on the aux battery. Cycling is what kills the battery, the deeper the cycling, the shorter the battery life. If you only go camping 3 times a year, the constant on and off of the car 2, 3, 4 times a day during the rest of the year will shorten the life of the aux battery. If you did not have the VSR, and left the switch on when camping, you would run the risk of flattening the starter battery. With my suggestion, the worst that can happen is you forget to switch the aux battery on to bring up to full charge. If this happens, just switch the car on for half an hour to bring it back to charged. You should aim to keep the "non used" battery at full charge anyway.

I have this arrangement on my JK, it also helps to protect the aux battery from the ridiculously high charge current. Most deep cycle batteries don't like 15.2V constantly...