With modern engine bays getting tighter than ever before, what’s the best way to get extra amp-hours into your dual-cab’s 12v setup?

GET THE GOOD GEAR!

Unless you’re Blind Freddy, you’ve probably realised just how much of a dint the whole dual-cab market has made on the 4WD scene.

Okay, we know they’ll never be as tough as a solid axle wagon, lift wheels, are lower, blah blah etc. But dual-cabs are the ultimate all-rounder – economical, powerful, capable of lugging big loads, and most importantly, they’re easily turned into incredible touring rigs.

However, at the centre of every excellent touring 4WD is a strong 12v system, and there’s a few things you should be aware of when it comes to upgrading the 12v setup in your modern dual-cab ute.

‘SMART’ ALTERNATORS – WHY?

Forgive us if you already know this, but there are still a lot of 4WDers who get caught out by this. You may or may not have heard the term ‘smart’ alternator. In an effort to increase overall fuel economy and meet ever-tightening emissions standards, manufacturers look for any tiny savings possible. It’s now at the stage where it has been identified that if an alternator doesn’t need to charge at full capacity – and hence at full load on the engine – the entire time, then savings can be made by backing it off.

That’s great in theory, but the problems come about when you try and charge one or more auxiliary batteries off that smart alternator. Most traditional voltage-sensing relay type isolators think that anything less than 13.5V or so means the engine is turned off, so often the auxiliary battery won’t charge at all, because the smart alternator will read the crank battery as full, and reduce charging output to as low as 13.0V. Yeah, that’s a problem…

SMART ALTERNATOR SOLUTION – DC/DC CHARGERS

Thankfully, there is a solution – a DC/DC charger. Think of it like the type of charger you’d have in your garage plugged into the power-point to charge up a car battery, just that it runs on 12v instead of 240v. A traditional dual-battery isolator works great for older style ‘Dumb’ alternators and simply directs the charge from the alternator to one battery or another. A DC/DC charger produces its own stable output power almost regardless of what the input voltage is.

If your vehicle has a smart alternator then you might need to consider a DC-DC charger like the CTEK D250SA to fully charge both your main and auxiliary batteries. The output current of your DC-DC charger will automatically sense and adjust the input and output into a safe charging current for both of your batteries.

LACK OF UNDER-BONNET SPACE

The biggest practical hurdle to installing dual batteries in a dual-cab ute often comes from a serious lack of under-bonnet space. Gone are the days of the old 1HZ 75 Series Cruisers where you could fit three N70 batteries under the bonnet!

These days ever-tightening engine bays you’re lucky to fit a single full-sized crank battery, let alone an auxiliary battery or two. But that’s not a bad thing – because the solution is to mount the auxiliary battery in the tub or tray, getting it away from that hot, crowded engine bay can end up prolonging the life of the battery.

MOUNTING BATTERIES IN YOUR TUB OR TRAY

Mounting an auxiliary battery in your tray or tub has multiple benefits. Firstly, it gets around that issue of lack of under-bonnet space. Secondly, it gets your expensive auxiliary battery away from hot turbos and exhaust manifolds in your engine bay, which can dramatically decrease the life of most batteries.

The other benefit of your storing your battery in your tray means it is placed right next to your fridge, meaning way less issues associated with voltage drop between an auxiliary battery mounted up in the engine bay, and a fridge in the rear of the ute.

Quality DC-DC chargers will automatically adjust any voltage drop caused by the resistance in long cables. To do this efficiently they are best mounted closer to the intended charge destination  i.e. the battery(s) you are trying to charge this means the output is as close as possible to an efficient charging current.