Nothing sucks worse than that gut-wrenching feeling of pulling up to camp and realising your camping fridge hasn’t been running for the last couple of hours. The little red light’s blinking and the temp gauge is either off completely, or it’s now reading 12°C. You open the 12v fridge to be punched with the smell of off meat, so you try and drown your sorrows with a drink but they’re all hotter than that last servo coffee you got on the way up.

It doesn’t matter if you’re just starting out in the 4WD game or you’ve been hitting the tracks for decades – 12v solar and power problems affect absolutely everyone. Whether you’ve DIY’d your setup or paid the pros to do it properly, you’re going to come across problems. Whether they’re little inconveniences or trip-enders comes down to how prepared you are with both the knowledge and the tools you’ve got, but thankfully it’s actually way easier to fix 99% of electrical problems than most people would think.

MOST POPULAR 12V TERMS EXPLAINED!

AMP HOURS: A measurement of how many amps a deep cycle battery can supply over a period of time. A 115Ah AGM battery that can safely be drained to 50% has say 57 amp-hours (Ah) of capacity. If a fridge draws an average of 3amps, then that battery can run the camping fridge for 57/3=about 19 hours before it gets down to 50%.

OPEN CIRCUIT: This is when there is a break in the electrical circuit that stops the power from flowing, such as a blown fuse.

SHORT CIRCUIT: In 4WD terms, when a cable that supplies power prematurely comes in contact with an earth like the body, it is called a short circuit.

DC/DC CHARGER: Acts similar to a 240v battery charger that you’d use to charge your batteries in the garage, except it is powered by 12v. A DC-DC Charger typically include an isolator to only charge when it senses the vehicle is running, and often has an in-built solar regulator to allow charging by camping solar panels.

VOLTAGE-SENSING RELAY: A basic relay that opens or closes depending on the voltage that is supplied to it. In a dual battery system, it works by opening when it senses enough voltage that it can tell the engine is running, allowing the auxiliary battery to connect to the charge system. When the vehicle is switched off, the relay closes, isolating the second battery and ensuring your fridge and lights can’t draw off your crank battery’s power.

SERIES WIRING: A way of joining two batteries positive to negative to double the voltage of the 4WD batteries. Used in older 24v diesel motors to get 24v by connecting two 12v batteries.

PARALLEL WIRING: A way of joining two or more batteries positive to positive and negative to negative, doubling the amp-hour capacity of the AGM battery bank without changing its voltage. Two 115Ah 12v batteries connected in parallel essentially forms one massive 230Ah 12v battery – which is what you’d want if you were powering a fridge or lights for a long time.

VOLTAGE DROP: Refers to the amount of voltage that is lost through a circuit, typically by under-sized electrical components in a 4WD install. 2mm twin-core wiring run from a battery under the bonnet all the way to a fridge in the rear might read 14.4v at the battery end, but the 12v fridge could possibly only be receiving 13v, tripping the low-voltage cut-out protection.

THE NUMBER ONE CAUSE OF ELECTRICAL PROBLEMS
The good news is the number one cause of 12v camping accessories problems can be fixed for $10 by adding extra earthing to your vehicle. It’s as simple as running cabling from your battery’s negative post through to a good clean, unpainted earth point on the body. At the same time, remove the big earth lead that runs from the negative battery post to the side of the engine block, and use sand-paper to thoroughly clean the lugs and the earth points. If you’re running AGM batteries in the rear of the vehicle, don’t rely on running earth cables all the way to the engine bay – add an extra earth to the chassis somewhere in the rear. You can never have too many earths!

INSTALLING A DUAL BATTERY ISOLATOR

Be aware of the temperature of where you install your dual battery charger. If you install it under the bonnet near not engine components, this can reduce the performance of the charger. If the 12v battery charger has a temperature compensator built it, it will reduce the charge level to compensate for the heat, which will result in an ineffective charge. That’s not to say you can’t run 12v equipment under the bonnet, just that you need to be aware of where it is positioned. Keep chargers away from hot exhaust manifolds and turbos, and up towards the rear of the engine bay if possible to protect from mud. DC-DC Chargers are best placed somewhere cool, dry and dust-free – like in the back of a vehicle.

SMART ALTERNATORS AND ELECTRICAL CAMPING GEAR
You might have heard about the term ‘smart’ alternators. Basically, these are alternators that don’t always provide the full level of output but rather vary their output depending on battery levels and load requirements. The general idea is that if the alternator doesn’t have to work at full capacity the whole time, it’ll save (very small) amounts of fuel by reducing load on the engine. The problem for 4WDers is that it means the alternator won’t always produce enough charge to properly charge an auxiliary battery, but there is a simple solution that involves a DC/DC charger with a  dedicated accessory input that triggers when the car’s turned on, and automatically starts the DC Charger charging the auxiliary battery.