Cole Hersee <span class="highlight">Wiring</span>

David,

I am assuming that the switch that you are talking about is really a solenoid about 30mm round and 50mm long and has 4 poles coming off the outside. If this is it then this is how it can be wired.

The two large poles have to be wired with at least 6mm wire and go to the positive terminal of either battery. One of small poles is to be wired to a good earth and the other can be wired in to the small black box on the drivers side of the engine bay.
In this black box with the lid removed there are a series of screws and fuses. The fuses are marked BAT, ACC ,ING and earth. If the small wire from the solenoid is wired to the ING screw and fuse it will be come active only when the ignition is on, ie, when the motor is running.
When the ignition is off the solenoid is turned off and the batteries are isolated.
All of the original wiring that runs the vehicle and accessories that come with with the vehicle are connected to the main starting battery. The second battery will only power what accessories that have been added to the vehicle and wired to that battery. Leaving the car radio on all night will flatten the main starting battery just the same as leaving the head lights on.
The position of the solenoid, cap up or cap down. I have always mounted the solenoid horizontally. The solenoid has a spring which disconnect the contacts when the power is turned off. If the solenoid is mounted vertical either way the spring is under a lot of force when on rough roads so mounting it horizontal there is less pressure on the spring.

Wayne

The switch will be installed so it switches the negative side of the batteries. When you're in position 1, only that battery can deliver any current as the earth for battery 2 is open circuited. Visa versa for position 2. When you're in the "both" position, both battery negatives are closed and you are drawing off both batteries. In the off position, both negatives are open circuit and the car will be "dead". If your switch is in the "both" or "1&2" position, you volt meter will indicate that both are being charged and with ignition on, no engine running they'll read the same too. Where you'll notice a difference is when you go bush for a day or 2 and run your fridge on say battery 2. When you check your meters, 2 may be reading lower than 1 ( because it has been doing all the work ) Once you've started your car ( on 1 if 2 was too soft ) switch to both and the flatter one will charge up as you drive home. Cheers....

Thanks bullwinkle
So it appears from what you have said my system is normal.
It appears that the majority of the 12v supplies in the vehicle come from bat 2 as there are cables from there to a relay panel. This panel has cables into the vehicle that have plugs attached for the supply accessories.
Even though these plugs are attached to bat 2 they will be live when the switch is on bat 1.
There is also a large red cable connecting the 2 positive bat terminals. I suppose this is how bat 1 supplies the system when bat 2 has its positive off by the CH switch.
Is it safe to switch the CH switch between 1 and 2 when engine is running?

David

Yes, you can switch between 1, 2 and "both" but don't switch it through the "Off" position as it's no good for your alternator. Cheers...