Thread: Dual battery system not working

G'day 2 rocks,
I don't think there is a problem in your duel battery sytem.
The isolator allows the second battery to charge while the engine is runing(uses an ignition feed, so fuel/starter in laymans terms).
When the motor is turned of it "isolates" the 2nd battery to allow you to use it without affecting the starting battery.
This way you can run your air compresor/fridge/ lights off the 2nd batt till the cows come home with out fear of running the starting battery flat.

It apears to me your starter batt is not right, might have just got flat when you did the work(inside light on ect.).
Give it a charge and get it tested after checking all the terminals and lead mounting points.

Meantime you should be able to jump start your car by hooking up the aux battery to your main battery with cables, providing that your aux battery is a cranking battery (which is a wise move in itself).

Looks like a simple 100 amp soleniod could be wired like alien d2 says through your ignition sometimes people put switches in to close the soleniod so you can use it for starting do you have a switch somwhere? Also if you start bat is to flat it may not have enough power to operate the soleniod when trying to kick the car over try jumper leads from the second battery

PS: those soleniods are very loud when they close try having someone turn the key and you listen for it to close.

Hi 2 Rocks, it actually sounds like your set up is working exactly how it should.

Most people are unaware that dual battery isolators also work in reverse.

This is very useful in situations like yours, where the cranking battery has gone flat, and you isolator has protected your auxiliary battery.

What you need to do is workout how your set up actually works. You have a solenoid as the switching device but you need to find what controls the solenoid.

There are two large connections on your solenoid, these go from battery to battery. Then there are two smaller connections. The wires on these connections control the operation of the solenoid.

What you have to do is follow each of these two smaller wires and see where they go.

One might be looped onto the same terminal where the cable coming from your cranking battery connects to the solenoid.

The other could go to a number of places and some may seem quite strange, like to your oil sensor.

OR, one wire might go straight to earth and the other to a switch.

Follow the two wires and post up what you find.

Thanks to all for the always excellent advice!

So yes, it does sound like the system is working properly and using a jump cable I could have started the car (I've taken the main batt out and whacked it on charge instead), as the 2nd battery has been 'isolated'.

It'd be a bit of a bugger though if after a few days away, running a fridge etc, I found the main battery dead and not enough juice left in the 2nd for a jump...

DriveSafe:

I'll follow the wires as suggested, but I also note that there is a wire coming off the main solenoid terminal on the RHS (the one for the 2nd battery) that has a male connector on it. There is another wire coming off the adjacent, smaller solenoid terminal with a female connector on it.

They have been disconnected for as long as I can recall but I always thought the two should be connected, but wasn't sure...??

Cheers
Mike

by linking those two terminals that you are describing you would energise the solonoid from the aux battery. if you had joined those two terminals you would have been able to start the engine. you could put a switch in for this purpose.

Dylan

From your pic you seem to have more wires than is needed for a simple setup before joining any loose wires I would follow what is there and work out what they do wouldnt want to short anything out
The simplest wireing would be something like this

starter bat pos to soleniod
soleniod to pos on 2nd bat
2nd bat neg to earth
an ignition wire to small terminal on soleniod
other small terminal on the soleniod to earth