Thread: Simple solenoid dual battery set up

Andrew, any chance of some details of your existing dual battery device?
Does it have any labels etc?

Fraser

Had one of those when our truck was new.
Be careful you don't parallel the batteries on starting, you can draw 1/2 the starting current from the second battery and fry the contacts in the relay.
I now have an electronic one that charges the second battery once the main battery is at full charge.
You can use that relay, but I would trigger it from a small Voltage Sensitive Relay from Redarc or similar.
cheers

I know it doesn't answer your question, but have you thought of using a large Marine switch. It's what I and a number of others use, mounted on the front of the seat box where it is easy to get at. Everything runs through the battery that's selected. Same with charging.

I have used this system for 22 years with never a problem.

Originally Posted by austastar

and fry the contacts in the relay.

yep.. that seems to be a common problem with the cheaper solenoids

the marine switch is fine if you have all normal cranking batteries or keep remembering to switch before you crank etc.

i use a traxide sc80 as it is set and forget :P

Go to the Traxide site and check out the SC40 and SC80. Much better battery management than a simple solenoid and not that expensive.

No need to connect to the aux/ign switch or anything either.

I've had an SC40 on two vehicles now and works a treat - install and forget.

There's others like Redarc, Pirahna but they are dearer.

Don't waste your time on electronic controllers, they are a waste of money.
Use the solonoid you have there and either make it activated by the Alternator or the Oil Pressure switch.
Mine is activated by the Alternator, so when the engine is running the battery's are in parrallel. It gets a little to tricky to wire it up to the Alternator sence output Terminal D+. You need to use a very small current relay or it kills the self excitation of the alternator. I used to have a drawing of this installation but Yahoo, fixed that. I will do it again and put it up here.

And place a fuse in the trigger wire for the solonoid. A friend in WA had a solonoid go short circuit ( must have been to earth) to the trigger wire and burnt out all his underbonnet wiring . Regard sPhilip A

i used this setup for years on my 2 door rangie and worked a treat........i can not see a problem having two differant batteries, well i didn't although i did join them with full size battery cable, there would be heaps of this setup out there

my defender came with a marine controler which works fine