12V systems for vehicle setup

Ron Moon — 1 May 2015

Electrical aftermarket accessories are an important consideration of setting up your vehicle and caravan/camper properly. It’s one area that can cause a lot of heartache when something goes wrong out on the road, far from anywhere.


Much of the standard wiring run in vehicles today is of minimal thickness and not designed to carry any real heavy current – or to run a powerpoint or fridge efficiently. So always ensure you run wire thick enough to handle the required current without any voltage drop (or at least a minimal voltage drop) and take the time and effort to solder as many connections as possible. Crimping wires and connectors often leads to poor electrical connections that can later cause unnecessary and hard-to-find electrical faults.

While blade-type fuses are generally okay, they can create an issue in heavy current applications. After having problems with the 80A fuse connector in the Patrol, I replaced it with an 80A circuit breaker. It’s been a simple, easy and reliable fix.


Dual battery systems are a lot more than something nice to have when you start long distance touring and camping.

Keeping those batteries charged and independent of one another, so that you always have a battery to start your vehicle, demands you have some form of battery isolator. Back in the good ol’ days, you could have a simple switch between the two batteries but this was a pain, which often resulted in two flat batteries.

Today, if you have a pretty simple engine management system, such as in my TD42 Patrol, a basic battery isolator, such as the Redarc Smart Start SBI isolator, will suffice. They’ll handle even more complicated systems and are bloody excellent, I reckon.

Complicated modern engines with electronic management and mapping of the fuel injection system may demand you have a battery isolator that incorporates microprocessor control. The DBE140S from Piranha Offroad Products is one that I’d recommend.


I’ve used a lot of different driving lights over the years and, if you are doing a lot of night driving, a good set of auxiliary lights will pay big dividends. But you don’t have to go over the top like you see on some rigs. There are Australian Design Rules (ADR) which regulate what you can do and these have been changed lately to reflect the increased use of LED lightbars and daytime running lights.

While LED driving lights are becoming more common (both ARB and Lightforce have models), I still prefer a set of HID driving lights to drive behind and for distance vision. Currently, we are running a set of Lightforce 170 Venom lights, which replaced a set of the bigger Lightforce 210 Genesis lights. They’re arguably the best lights I’ve ever used.

I’ve also upgraded my headlights, because so many standard vehicles have pretty terrible lights on high beam. We first added a Piranha Super Loom which ensures we get full voltage to the headlights, and then we fitted some Narva Arctic Plus 50 globes, which give out a much whiter, cleaner light. These are a big improvement over the standard variety. You can go for even more high performance globes, but we’ve found their usable life is dramatically shorter and they don’t seem to like the continual vibration that we find on corrugated roads.


The normal single cigarette lighter/power outlet is just not enough for us anymore. Apart from the range of heavy-duty power outlets I have down the back of the Patrol for running the fridge, lights and so on, we now sport six outlets on the front centre console – two normal cigarette lighter sockets, a Merit socket and two USB power outlets.

Use some heavy-duty wire to run to the power outlets and make sure they are protected with a fuse of about 15A. When buying a USB outlet or adaptor, buy an outlet rated at 2A or more as iPads and the like require that as a minimum to charge. Many USB outlets are rated at just one or 1.5A and will not charge many devices.


We just swapped our electric brake controller to a Redarc Tow-Pro, which is the latest electric brake controller to hit the market. It is a beauty, which we have tested extensively on the highways, byways and mountains of Victoria over the past few weeks.

The Tow-Pro can be used to control both electric and electric/hydraulic trailer brakes and will operate from either 12 or 24V vehicle electrical systems. Unlike most units, the main control box is hidden somewhere behind the dash and the only visible sign is the control switch.

You can easily select ‘auto mode’ which is suitable for highway work, or ‘user mode’ for offroad work, while simply pressing the switch will also activate the trailer brakes.

This unit features a three-axis accelerometer where most other brake controllers depend on a pendulum setup or a single-axis accelerometer to determine a change in momentum. On initial set-up, the Tow-Pro calibrates itself and, after a few seconds, it will work properly in forward or reverse. All you really have to choose is whether to run in auto or user-control mode and then adjust the amount of braking your rig requires. It’s pretty simple, although it took me a while to figure out what setting (anywhere between 0 and 10) was required for optimum braking for our camper. 


A few months ago, I changed my UHF radio to the latest 80-channel unit and opted for a GME TX4500S DIN-size 5W radio. The new unit has all the normal radio features along with unique facilities as a voice inversion scrambler and sel-call.

When it comes to navigation, I run a Hema HN-7 Navigator with a 7in screen. This unit comes with the complete Hema digital map collection and the 1:250K topographic maps of all of Australia when in 4WD navigation mode. In street navigation mode, it runs the iGo Primo software, which seems to be better than most similar software, while still having its own peculiarities.


In recent months, I’ve fitted some extra gauges to the Patrol to make monitoring the engine functions a lot better. These include a Redarc dual voltage gauge, which constantly monitors both my main battery and the auxillary battery and also gives a digital readout of the current output of the alternator.

The second Redarc gauge I’ve had fitted by the crew at Outback 4WD monitors the turbo with a boost readout and exhaust gas temperature (EGT) display. A digital readout of engine oil pressure on the same gauge rounds out the display.

Just to reiterate, if you ensure any accessory you fit is wired in correctly with good connections and fuses all round, you will have little or no trouble with any of them. If you try the easy short-cuts, you will pay the price – generally when you are kilometres from anywhere!

The full feature appeared in Caravan World #536 April 2015. 


12V Nissan Patrol Dual battery system GME TX4500S DIN-size 5W radio


Ron Moon