Words by Ramsay Beacham
Photography by Lachlan Payne

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Back in the days when life was much simpler, recreational 4WDers used eskies, gas lanterns and PTO winches. None of these relied on the marvels of electricity. Since those glorious days, these items have predominantly been replaced by 12V fridges, fluoros and electric winches, which all rely on a constant 12V supply.

Supercheap can sell you everything you need for a DIY dual-battery install. Battery tray, clamps, nuts, bolts, washers and screws can all be had at super-cheap pricing	All makes of 4WD will be different, but in a GQ Patrol there is a spot almost made for a second battery. Use some big, penny-flat washers to spread the load over a larger area

Most 4WDs incorporate a 12V electrical system, and thus 12V accessories have become very handy indeed. However, they also brought us the era of the dreaded flat battery. Then, one rainy day, a very bright spark decided that two batteries would be better than one. This gave us one to run our accessories and one to remain fully primed for cranking up the engine.

Before attempting any electrical or welding work on your fourby, always disconnect battery earth cables. 12V generally isn’t dangerous, but can upset your electrical system with short circuits	Conventional wire strippers won’t cut it on this size of wire. Roll a sharp knife around the rubber with light pressure about 10mm back, and then just slide the insulation off

Short of installing a second alternator, this system required a means of isolating the two batteries whenever the engine wasn’t running to eliminate the possibility of two flat batteries.

As so often is the case, there is more than one way to skin a cat, and there are practical solutions to isolate two batteries. Heavy-duty switches are the simplest and most obvious, but they do rely on a certain individual remembering when to flick them on and off and are definitely not foolproof.

After bending the standard crimpers, we went for the multi-grip. This gives you more leverage than a loaded shotgun. Alternatively, you will need a decent soldering iron and not a year 10 electronics jobbie	The Baintech unit comes with all the associated hardware, right down to pre-cut shrink-wrap. If you decide to go the cheaper starter-solenoid route, you have to source all this yourself

Another option is the heavy-duty solenoid that originated as a means of supplying big doses of 12V to some older starter motors. These have been one of the most popular dual-battery isolators in days gone by due to their simplicity, reliability and most of all cost effectiveness. At around $13 a pop, they represent exceptional value for money.