by Dan Everett
Unless you're the kind of 4WDer who counts a tin of beans and a head torch as a great weekend off in the bush, chances are you'd benefit from a few 12V upgrades. While they rarely make your 4WD more capable, there's no denying they make things a whole lot more comfortable.
After all, it's never fun trying to cook up a feed by the dying light of a head torch, especially while your mates are having a great time by the campfire. In fact it's a pretty safe bet there's been more than a few divorces due to warm steaks, burnt fuses and wives tripping over tent pegs sticking out of the ground in the dark.
The other big benefit of 12V modifications is they're cheap, dirt cheap. Some of the more basic upgrades can be done in an hour or two with change from $20.
The only real downside is auto-electricians can charge like a wounded bull, and if you don't know what you're doing, electrical work can seem about as clear cut as black magic.
The truth is, 12V wiring is hands down some of the easiest work you can do to your 4WD, if you plan it out. We've put together a quick run-down on the five best 12V modifications, how hard they are, and even an easy wiring diagram with a few extra tips thrown in for good measure.
A good quality dual battery system is the brain of any 12V setup. You can throw batteries in till the cows come home, if they're not wired with a bit of forward thinking it's not going to do you any good.
There are a few options on the market with smart controllers that promise to keep your batteries happier than a pig in ….. they do all sorts of other clever tricks like reduce the load on your alternator and ensure you get the best charge as quick as possible.
The downside is they can be expensive. If you're penny pinching but still keen to head bush a simple solenoid system is normally all you need.
Think of it like hooking up a set of jumper leads to a 2nd battery to charge it, then disconnecting them so you don't run your main battery flat overnight. Simple stuff.
What you need to know
A solenoid dual battery system is often known as a dumb dual battery system. It sounds mean but basically it just means it doesn't do any thinking for you so you'll need to monitor it to ensure your main battery stays charged and only connect them when you're up and running.
With your dual battery system installed it's time to start adding accessories. Truthfully, depending on what you're planning on running you can even do something like this off your main battery.
The easy trap to fall into, and one we've seen time and time again, is running each accessory directly to the battery with an inline fuse. The problem with this is you end up with messy wiring with the potential for things to rub and short out. It's near on impossible to find which fuse you're after if something goes pop, and your batteries end up looking like they're covered in spaghetti.
A standalone fuse block allows you to run one cable from the battery into your cargo area and then run your accessories from there. It keeps everything neat, organised, and makes adding more accessories later a pain-free process.
What you need to know
With all your accessories running through the one cable it's going to see a whole lot of load on it. Inline fuses and off the shelf wiring looms are never going to cut it. Thankfully, the guys in the doof doof scene have an easy solution with their amplifier wiring kits. They can be picked up for less than $100 from most auto parts stores, come with everything you need to wire up a fuse panel and include an easily replaceable glass in line fuse and extra thick cabling more than up to the task of handling a large load.
On-board air is one of those modifications that can make you look like a well-oiled off-roading machine. You've gotta admit, it's pretty impressive seeing someone pop an airline into a fitting coming through the bull bar, flick a switch and start pumping their tyres up.
The good news is it's ridiculously simple to make happen. it's as simple as finding somewhere to bolt the compressor down, running a simple relay to a switch on the dash and grabbing a power feed from your conveniently located fuse block you fitted earlier and then an airline from the compressor, through your floor and into your bulbar.
From here it's not much harder to run an on-board tank making the use of air tools out on the tracks an option. Simply add an air tank into the line and add a pressure switch to turn the compressor on and off as it's required.
What you need to know
Installing on-board air into your 4WD is simple, but it can easily go wrong. Compressors get hot, real hot. So it's vital to keep them as far away as possible from anything that could easily go up in flames. They also need a source of clean air. One easy solution for this is mounting the compressor underneath your 4WD or in your engine bay and adding an extended air intake into your factory airbox. Sure it makes things a little more complicated but it's a sure fire way to make your on-board air system last for years to come.
SIDE/REAR WORK LIGHT
LED strip lighting under an awning is one of the quickest and easiest way to improve your campsite. Stick it up there, wire an inline switch into a lead and plug it into your cigarette lighter. The only real downside is it only lights the immediate area. Something that can cause issues in a less than perfect campsite.
The trusty old work light is a near perfect fix for this. They can be mounted on something as simple as a telescopic tent post and wired up in less time than it takes to drink a 6-pack of your favourite brew.
They can also be pointed in just about any direction you want, making them perfect for cooking, chopping up firewood, or waking your snoring mate up at 3am. If you're feeling extra clever they can double as a high-powered reverse light with some trick wiring.
What you need to now
Extra lighting can be a legal grey area depending on each state. So it's worth running your eyes over your local laws before wiring a work light into your factory reverse lights.
That said there's nothing stopping you from wiring the work light to a dash mounted switch for easy access when you need a little extra light reversing, or to deter tailgaters.
Let's face it, driving at night in rural areas isn't normally the smartest thing to do. Unfortunately it's often unavoidable, making animal strikes a serious possibility. A set of driving lights is cheap insurance to keep Skippy out of your bull bar and light up the track ahead.
Whether you're fitting up LEDs, wiring in a set of HIDs, or bolting on a set of Halogen spotties there are a few laws that can see you in strife should you wire things up wrong. The safest bet to keep the plod off your back is having the auxiliary lighting wired up to a separate switch that is only energised when your factory high-beams are switched on.
It sounds complicated, but with a switch, a couple of metres of cable and a relay it's about as simple as you can get.
If you're wiring driving lights up onto the roof you can follow the same steps as regular driving lights, although some clever 4WDers will run their wiring through a plug making for easy removal if the roof rack has to come off.
What you need to know
Factory headlights come in one of two flavours, either positively or negatively switched. With a positive switched light there's always an earth present, and the positive side of the circuit gets turned on and off from the switch. A negatively switched light has 12V power constantly and switches the earth path. Be sure to find out what your lights are before picking up the soldering iron. Getting it wrong has blown more than a few fuses over the years.
WHAT DOES IT ALL MEAN
Accessory - An electrical circuit that has power with the ignition on run or accessory position
Amperage - The measurement of the flow of electricity. Think of electricity like water going through a hose. The Amperage is how much water is flowing, often referred to as current.
AWG - American Wire Gauge; standard measuring gauge wire thickness, lower the number, thicker the cable
Battery - The heart of your vehicles 12V system, most commonly lead plates in a solution of sulphuric acid
Cable - A cable is a set of wires, usually encased in an outer protective jacket.
Capacitor - A device which collects, stores and releases electrical energy
Chassis - The frame or body of your vehicle, also functions as the return path for 12V electricity
Conductor - The copper or aluminium inside a cable and the path of electricity
DC - Electrical Current that flows in one direction (Opposite to AC - house power)
Fuse - A safety device consisting of a strip of wire that melts and breaks an electric circuit if the current exceeds a safe level
Ground - The circuits return path to the battery negative terminal
Ignition - An electrical circuit that has power with the ignition on the run position
Insulation - The fine rubber or plastic case covering cables and terminals
IP Rating - Ingress Protection Rating, a two digit code specifying the level of protection from foreign objects with the first digit referring to protection from solids and the second digit referring to protection from liquids
Relay - An electrically operated switch that uses a small amount of current to control a larger amount of current
Rest - The status of a circuit when not in use
Schematic - The layout or drawing of an electrical circuit or circuits
SPDT - Single Pole Double Throw. A relay or switch that has one contact which can connect two other contacts
SPST - Single Pole Single Throw. A relay or switch that has one contact which can connect one set of contacts
Terminal - A terminal is the point at which a conductor from an electrical component comes to an end and provides a point of connection to external circuits
Voltage - If Amps is how much water is coming through a hose, think of Voltage as how much force it's under
Watt - A unit of power, defined as one joule per second. Wattage is calculated as Voltage x Amperage