April 5th, 2020

When it comes to camping and caravanning, it's important to keep your fridge running and your food cold. In the past, many people relied on gas-powered fridges while on the move, but this practice is now considered unsafe. So, what's the solution?

If your fridge can operate on 12V, the best option is to wire up a direct connection from your tow vehicle to the van. While some wagons may have a 12V socket in the cargo area, it's likely not sufficient to power a three-way fridge in your caravan due to voltage drop.

Even absorption fridges, which can handle less than 12V better than compressor fridges, won't cool properly if the voltage is too low. The key is to provide as much power as possible to your fridge.

For optimal results, it's recommended to run a minimum of 6mm wire directly from your battery. Keep in mind that in Australia, wire diameter is measured including the insulation, so be sure to factor that into your calculations. By following these guidelines, you can ensure that your fridge stays cool and your food stays fresh on even the longest of journeys.

To ensure that your caravan fridge runs smoothly while on the move, it's crucial to use the right wiring configuration. In Australia, 6mm wire is classified based on the insulation included, so the actual copper wire diameter is around 4.5-5mm. This wire diameter is compatible with running a caravan fridge in terms of voltage drop, provided that the wiring route is reasonably direct and doesn't exceed six meters.

For longer distances, such as seven meters to reach the rear of your vehicle, it's essential to increase the wire diameter to avoid excessive voltage drop. Once you have determined the correct wire diameter and length, you will need to consider the connection between your vehicle and caravan. The standard fitment for most caravans these days is the 50A Anderson plug, which can carry plenty of current and provides a positive connection.

It's also important to include an inline fuse or reset breaker switch and install a relay to power the plug only when the vehicle's accessory circuit is on. This prevents the fridge from draining the vehicle battery when the engine is off, which could result in a dead battery.

Note that some modern utes and 4X4's may have more complicated power systems that require specialist attention. If you're unsure or not confident about using our advice, please contact your manufacturer or see a reputable installer for help. By following these technical guidelines, you can ensure that your caravan fridge operates efficiently and reliably during your travels.

To wire your caravan fridge, start by threading the wire through your vehicle. You can do this by running the wire underneath your vehicle, alongside or in the chassis rail into the engine bay, or by running it inside the vehicle under the carpet and through the firewall into the engine bay. Although running the wire underneath can be easier, it can be complicated by the need to ensure that the wire isn't hanging down anywhere or subject to chafing.

The easiest place to start is in the cabin near the tap-in point for the accessory power, or at the rear of the vehicle. It's best to avoid starting at the engine bay because you'll probably end up having to thread nearly six meters of wire through a tight access grommet in the firewall. Instead, thread a meter or so of wire from the cabin into the engine bay to the battery.

Once you've routed the wire to the battery (but not yet connected), connect the inline fuse or reset breaker. While an inline fuse is a safer option, as it makes the circuit inoperative once it blows, a reset breaker will keep tripping and resetting the circuit if there's a constant short.

Crimp the inline fuse wire to the positive (red) wire of the dual-core 6mm wire, and crimp an eyelet to the other end to fit to the battery's positive terminal. Crimp an eyelet connector to the negative (black) wire of the 6mm dual-core wire, which will later be fitted to the negative battery terminal.

If you're fitting a relay to make the power source operate only when the vehicle is on (or in the accessories position), it can be fitted along the dual-core wire wherever a 12V accessory power feed can be sourced. Hook up the accessories power source to the connection pin numbered 86 on the relay and earth it through the pin numbered 85.

Cut the dual-core 6mm wire, crimp connectors onto it, and plug the wire from the battery into the relay at the pin numbered 30. Connect the power out to the rear of the vehicle to the 87 pin. Secure the relay by either screwing it into an under-dash surface or cable-tying it to a wiring loom or bracket. Ensure that the wiring and the relay do not obstruct the foot pedals or steering column.

Once the wire has been threaded through to the towbar area near the standard trailer connector, connect the Anderson plug. Use an Anderson plug holder to attach the plug to the vehicle's towbar, avoiding getting debris and dirt in the connector. Crimp the connectors to the wire, ensuring that you don't mix up the positive and negative wires, and fit them into the Anderson plug.

Finally, fit a 20A fuse into the inline fuse holder and attach the wires to the correct battery terminals. Test your circuit by putting a multimeter or test light across the Anderson plug terminals with the vehicle's engine running and the caravan's fridge operating. The voltage at the Anderson plug terminals should be almost the same as at the vehicle's battery terminals. This is important because voltage can drop under load if the cable sizing is too small or there's a bad connection. By following these steps carefully, you can successfully wire your caravan fridge and keep your food fresh on the go.

Written by Tom Crew

Gather the parts you’ll need for this job: 6mm dual core wire, a relay, inline fuse and connectors.

Start by feeding the wire from the rear of the vehicle.

Continue to thread the wire though to the front of the vehicle via the shortest route.

Wire up the relay and connect it (preferably) to accessories power.

Cut the outer insulation of the wire to prepare the connections at the battery.

Connect the inline fuse and connectors to the 6mm wire. The inline fuse it connected to the positive wire.

Attach the Anderson plug connectors to the 6mm wire.

Fit the Anderson plug to the towbar

Attach the connectors to the vehicle’s battery, ensuring positive to positive, negative to negative.