Duel Battery Setup

Thanks Allan,

Appreciate the advice, If I could impose a little more, does that mean I continue to run the 12v engel charger? and will it run the aux batterys down together or drain the BatPac first?

I assumed that the charger was a 12v dc to dc charger from the main cranking battery (and hence, alternator) to the auxiliary battery.

Regardless, with the BatPac in parallel with the aux battery, they will behave as though one battery during charging and discharging. I would have thought that the BatPac was to be used to run the fridge when removed from the vehicle and be recharged when returned to the vehicle. Have I got that all wrong?

The alternative is that if left permanently together, the BatPac will simply be adding some capacity to the aux battery.

Thank again Allan
To give a little more detail, I already had the Batpac and was using it in our Hilux. Having recently purchased the Cruiser I thought that I would ad a duel battery system as it has more space under the bonnet.
Seems a waist to discard the Batpac and was thinking it would give us additional power when stationary and would also allow the option of portability should we ever require. Having said that the fridge usually remains in the truck.

Yep, that would be OK Jack. The BatPac will add some capacity to your aux system and be available for off-vehicle use also. Depending on the battery types of the aux and BatPac batteries it may not be a perfect match for charging and thus stored capacity but will be near enough and certainly better than the aux battery alone.

Thanks Allan
Greatly appreciated, happy travells and look us up when you next head south.
Cheers, Jack

Thanks John,
Appreciate your taking the time to assist.
As you've no doubt guessed Im a relitive novice when it comes to all things electrical.
At this stage I am planning to mount the Deep cycle battery up front in the space provided, I have already wired in the batpacs charger and that now fits snugly into the rear of the truck not far from the Batpac. If I'm reading you correctly you would suggest that I take the existing positive wire from the main battery and attach it to the Auxiliary battery instead and then just plug it in as normal to the Batpac which in turn plugs into the fridge is that correct? Should I have fuses in the positive wires?
Thanks again John

Jack

High Jack,

First - Apart from the leads going to the starter and the vehicle's own fuses, EVERY other connection to any battery should pass through a fuse close to the battery. There is a lot of energy stored in a battery - enough to start a fire if a very high current flows, as can happen if the insulation is damaged and the bare +12V wire touches the vehicle chassis. A fuse (I use 20A or 30A fuses close to batteries) will protect against this.

My approach in your case would be to feed from the cranking battery through a fuse then through a relay (see below), through another fuse to the AGM. The line to the back of the vehicle should be fairly heavy (at least 6 square mm copper) and I'd connect it on the AGM side of the relay. This point is secured by the 2 fuses and will carry current from the alternator when the engine is running, and from the AGM when the engine is stopped.

At the back, I'd run the feed from the front to the 12v charger and the output of the charger to the Engel battery pack and fridge.

The relay - All of this extra wiring and batteries must be disconnected from the cranking battery when the engine isn't running. A relay is simply an electrically operated switch. A simple relay will do what's required - the cheapest (<$20) way is to use a 30A headlight relay, which is operated by the ignition circuit. Better still through a switch connecting it to the ignition circuit. The switch will allow you to manually turn on the relay, but only if the ignition is turned on; this way you can leave everything disconnected until the motor is running and delivering current.

A more popular option is to use a VSR - voltage sensing relay ($100+). This will make the connection automatically, but only after charging voltage is present. They are said to delay making a connection until the cranking battery has been charged, but in my experience they usually operate as soon as the alternator is up to speed. I use the cheap system, with a few embellishments to render it fully automatic - bit complicated to describe here!

Hope that all makes sense!

Cheers

John

Thanks again guys,

I cant believe how helpfull the people are in this forum. Its good to know that no matter how busy life gets, we still have people who retain those great Aussie values and are always happy to help!
Looking forward to hopfully returning the favour at some stage in the future.

Many Thanks