A dual battery system in your 4×4 lets you run all sorts of 12v gear, like portable fridges, LED camp lights and inverters. That’s all the kind of camping gear that makes camping more enjoyable and comfortable, and there’d be few campers out there who don’t already have a dual battery system or aren’t planning on having one installed soon. However if you want to extend your 12V system’s ability to power all your portable camping gear for more than one or two nights at a time, you may find that a single auxiliary deep-cycle battery isn’t enough and that you’re running out of power. Solar panels can go a long way towards helping extend the life of your deep cycle battery, but solar panels can’t store power, they can only produce it. That means when the sun isn’t shining, you’re back to relying on your battery to keep all your 12v gear powered. Here at 4WD Supacentre, we sell two different sized AGM deep cycle batteries – a 98Ah battery that’s perfect for powering just about anything overnight, and a 115Ah battery that has extra reserve capacity to get you right through the next day too. But what if you want even more power?

These days it’s very common to run more than one auxiliary deep cycle battery in your 4×4 or van. If you connect multiple deep cycle batteries together you create a large battery bank that, if wired correctly, can power your campsite for days. However there are right and wrong ways to go about wiring multiple AGM deep cycle batteries together, and if you get it wrong you’ll either cause a lot of problems, or you’ll severely reduce the life of your batteries. Thankfully it’s easy to wire two or more AGM 4×4 batteries together so they work as they should.

The first thing you should be aware of is the difference between wiring 4×4 batteries in series, and in parallel. If you wire batteries in ‘series’, you connect one battery’s terminals to the opposite terminals on the second battery. This doubles the voltage of the batteries, but the amp rating remains the same. Let’s use two of the Adventure Kings 12v 115Ah AGM batteries for example. Wiring two of them in series would produce a 24v 115Ah battery – not what you want. You haven’t increased the capacity of the battery, just the voltage.

Instead, what you need to do is wire the batteries in parallel. This is where you connect positive to positive, and negative to negative. In the same scenario using the same Adventure Kings 12v 115Ah AGM batteries, you’d effectively end up with one 12v 230Ah battery, which is exactly what you want.

An important point to note, however, is that you shouldn’t just connect one battery to the second, and then simply power all your accessories by connecting to one of the two batteries. What happens then, is the battery that has the accessories connected to it, drains its power quicker than the other battery. Same with connecting power cables to charge the batteries – the one that’s connected directly to the charging cables from your dual battery system will receive the majority of the charge, and the other battery won’t get much at all.

What’s the solution? Connect both deep cycle batteries together like we mentioned earlier, with the positive to positive and negative to negative. Then, when it comes time to connect the charging cables from your dual battery system or the power cables from your electrical accessories, connect the positive to one battery and the negative to the other one.

What this does, is it forces the electrical current to flow evenly throughout both batteries, instead of favouring one. Both of your 4×4 batteries will discharge or drain at the same rate, and they’ll also recharge at the same rate too. Neither deep cycle battery will be relied upon more heavily than the other, which means you’ll be using both equally. That extends the life of both batteries, rather than working one deep-cycle battery much harder than the other.

The 4WD Supacentre range of Adventure Kings deep-cycle AGM batteries are built for 4WDing. They’re tough, and their completely-sealed design means they’re able to be safely run inside the rear of a vehicle or a canopy. They’re perfect for powering your entire campsite, and now you know the correct way to wire them up too!