If you’re just about to start investing in your 4WD’s 12v system, then the first thing you’ll want to fit is some form of dual battery kit. A dual battery is at the heart of every 12v system, and lets you run a fridge, lights, inverters and anything else electrical you want to around camp, without risking draining your crank battery to the point where you can’t start your engine the next morning. Dual battery systems come in many different forms but the basic idea is still the same – when the motor is running, charge is directed into the auxiliary deep-cycle battery, and when the motor is turned off, the dual battery isolator disconnects the second battery from the starter battery.

The Adventure Kings Smart Isolator Dual Battery Kit is a beaut bit of gear that comes with everything you need to install a dual battery system into your 4WD, minus the second battery. This clever bit of gear is brilliant in its simplicity, because the Adventure Kings Smart Isolator is so simple that any complicated fail-points are taken out of the equation. It works by using what is known as a voltage-sensing relay. When the Adventure Kings Smart Isolator sees an input voltage of at least 13.5v, it understands that the engine is running and the alternator is charging the starter battery. When it sees this voltage it then connects the second battery to the first one, allowing the alternator to charge both batteries in the process.

When you pull up at camp, the reverse happens to disconnect the two batteries and isolate the deep-cycle battery from the starter battery. When the Adventure Kings Smart Isolators sees the input voltage drop below 13.1v, it understands the vehicle has been turned off and so it disconnects the second battery from the first.

So what types of vehicles are the Adventure Kings Smart Isolator Dual Battery Kits suited to? Generally speaking, any vehicle built before about 2008 will be suitable for having this type of dual battery isolator installed. That’s because the alternator will be a traditional type, controlled by the fan belt only. When the engine is on, the belt spins on the crankshaft pulley which in turn spins the alternator, producing power at a steady rate. The only thing that can affect how much power is produced is whether the belt is tight or not, or whether the alternator is healthy.

On the flipside, modern 4x4s built after about 2008 will typically feature ‘smart’ alternators which are controlled not just by the fan belt, but by the vehicle’s computer. When the vehicle senses the crank battery is full, it can electronically reduce the rate of charge coming out of the alternator, down to as low as 13.0V. The problem here is in this scenario, the isolator is looking for a minimum of 13.5v to see the engine as running, so it won’t often connect the deep-cycle battery to the starter battery. As a result, the starter battery won’t receive anywhere near the charge it needs.

What’s the solution then for modern vehicles? You’ll need to step up to a DC/DC charger like the CTEK D250SA, which essentially functions like the type of battery charger you’d use in your garage. It produces a charge specifically for the battery being charged, as opposed to the smart isolator simply directing the charge between the crank and deep cycle batteries. The only difference the D250SA has to the type of charger you’d use in your garage, is that instead of running off a 240v powerpoint, it runs off 12v power. That’s where the name DC/DC charger comes from – it inputs DC voltage, and outputs DC voltage. It is also designed to deal with varying rates of input voltage, and can handle the odd, lower voltages that a smart isolator puts out whilst still delivering a full rate of charge to ensure your deep-cycle battery is constantly topped up.

Remember as well that 4WD Supacentre has a price-match guarantee on the entire range of CTEK gear that we sell. If you find a cheaper price on Aussie stock elsewhere, we’ll match it! Terms and conditions apply, see https://www.4wdsupacentre.com.au/terms#ctek.