Towing a Caravan Out of Melbourne: Electrical Prep

This guide is for Melbourne caravanners and camper trailer owners planning a run down the Great Ocean Road, up into the High Country or north along the Hume. It looks at what each trip asks of your rig's electrics, sets out the national trailer brake rules carefully, and gives a practical check list for the night before you leave.

How can we help?

Need it fixed?

Find a local Towing a Caravan Out of Melbourne: Electrical Prep auto electrician for anything from a flat battery to a full fit-out.

Find an auto electrician

Buying parts?

Quality auto electrical parts from Ozautoelectrics, an established Australian supplier since 2010, dispatched through a nationwide network. For retail and trade buyers.

Shop parts

Doing it yourself?

Free step-by-step guides written for Victoria conditions, with the parts you’ll need listed for each job.

Browse DIY guides

Auto electrician in Towing a Caravan Out of Melbourne: Electrical Prep?

Are you an auto electrical business? List your business on this site.

List your business on this site

Three classic trips, three different demands

The Great Ocean Road runs about 240 km from Torquay to Allansford near Warrnambool, through Anglesea, Lorne, Apollo Bay and Port Campbell. It is a two-lane road with one lane each way, tight bends, cliffs and speed limits that change often between 50 and 100 km/h. For a van, that means constant light braking and a lot of indicator use. Brakes that grab unevenly, or a controller set too soft, become obvious within the first hour past Lorne.

The Hume Freeway is the opposite. The M31 runs about 295 km from Thomastown on Melbourne's northern edge to Wodonga, bypassing Seymour, Benalla and Wangaratta. It is long, fast and fairly gentle. Here the electrical load is steady: the fridge running on 12V, the van battery charging, and lights on for hours if you leave early or arrive late.

The High Country combines both. You can cruise up the Hume or the Maroondah Highway, then face long climbs and descents on mountain roads into towns like Mansfield and Bright. That is where your brake controller and van brakes earn their keep, and where a flat van battery at a bush camp is a real nuisance.

Trailer brake rules, stated carefully

Brake requirements for trailers built in Australia come from the national standard, Australian Design Rule 38/05 Trailer Brake Systems. Its thresholds use gross trailer mass (GTM), which is the mass carried on the trailer's axles, except the top threshold, which uses aggregate trailer mass (ATM). In summary:

• Up to 750 kg GTM: ADR 38 does not require brakes, but any brakes that are fitted must work.
• Over 750 kg and up to 2 tonnes GTM: a working brake system is required, and overrun (override) brakes are allowed.
• Over 2 tonnes GTM: brakes on all wheels, controlled by a signal from the tow vehicle rather than overrun, plus an emergency breakaway system that applies the brakes automatically if the trailer comes off, and keeps them on for at least 15 minutes.
• Over 4.5 tonnes ATM: further requirements apply, including a parking brake and more demanding brake systems.

Check the Victorian side too

Victoria registers and inspects trailers and caravans, and VicRoads publishes safe towing advice, including a pre-trip caravan checklist. Its safe caravanning page reminds you that the loaded van must not exceed the van maker's limit, the car maker's towing limit or the towbar's rating, and that brakes and external lights must be working. It also says extension mirrors may be needed when towing and must come off when you are not.

Rules and their interpretation can change, so treat this guide as a starting point. Check your van's compliance plate and the current VicRoads information before buying a controller or changing your setup.

Setting up the brake controller

A van with electric brakes needs a controller in the tow vehicle. Proportional controllers sense the car's deceleration and apply the van brakes in step with it. Time-delay controllers build braking over a preset time. Proportional units suit the stop-start bends of the Great Ocean Road and the long descents of the High Country better, because they respond to what the car is actually doing.

Set the gain with the van loaded for the trip, not empty in the driveway. Find a quiet, flat street, get to about 40 km/h and brake firmly. You want the van to pull up with the car, not push it or lock its wheels. Learn where the manual control is so you can use it without looking. A gentle pull on the manual lever is a recognised way to settle a van that starts to sway.

Install the controller with a properly sized, fused supply from the battery and a solid earth. Many late-model utes and SUVs need a specific plug-in harness. Our guide to installing an electric brake controller covers the basics.

Keeping the van battery charged on the road

On a long Hume run you would expect the van battery to arrive full. Often it doesn't. The cable from the front of the car to the van's battery can be eight metres or more, and thin cable loses a lot of voltage over that distance. Many newer tow vehicles also have smart alternators that drop their output once the car's own battery is charged.

A DC-DC charger solves both problems by boosting the voltage and charging the van battery properly for its chemistry. Lithium van batteries in particular need the right charge profile. The cable feeding the charger still matters, so size it for the current and the full length of the run. Our guides on what size cable you need and why a caravan battery isn't charging while towing go into detail.

If you plan to stay at free camps in the High Country, add up what the fridge, lights, water pump and devices use each day, and compare that to your battery and solar. Cold, cloudy mountain days can cut solar output well below what you'd see on the coast in summer.

Plugs, sockets and the breakaway battery

Many vans use a 12-pin plug to carry lights, brakes, battery charging and a separate heavy earth. Others use a 7-pin plug for lights and brakes plus an Anderson plug for charging. Either is fine if both ends match and every pin is wired. Coastal air on the Great Ocean Road and dust on unsealed High Country tracks both get into plugs, so clean them and keep the caps closed.

If your van has a breakaway system, its small battery must be charged for it to work. Test it with the system's test button or indicator before every trip, and clip the lanyard to a solid point on the car, separate from the safety chains.

The night-before check list

Do this at home, where fixing a fault is easy, rather than at a roadside stop near Benalla or a lookout above Apollo Bay.

• Hitch up and test tail lights, brake lights, indicators, clearance and number plate lights with a helper.
• Roll forward slowly and apply the controller's manual lever. The van should drag the car to a stop.
• Test the breakaway battery and check the lanyard.
• Start the engine and confirm the van's battery monitor shows charging.
• Check the plug is fully seated and the cable has slack for tight turns without dragging.
• Make sure your car's battery and alternator are in good shape. Towing adds load.

Booking work before you go

Controllers, DC-DC chargers and new plugs are best fitted a few weeks before departure, so you can do a test run and have any niggles sorted. If you are heading north up the Hume, auto electricians around Campbellfield and the Whittlesea area are on your way out. For the Great Ocean Road via Geelong, try the Wyndham area.

Parts for this job

Order quality parts online from Auto Electrical Australia, dispatched Australia-wide.

Get it done: get a quoteDo it yourself: shop electric brake controllers

Get it done: get a quoteDo it yourself: shop DC-DC chargers

Get it done: get a quoteDo it yourself: shop 12-pin trailer plugs

Get it done: get a quoteDo it yourself: shop breakaway kits

Questions Melbourne drivers ask

Does my caravan need electric brakes to tow it in Victoria?

It depends on the van's mass. Under ADR 38, trailers over 750 kg GTM need working brakes, and overrun brakes are allowed up to 2 tonnes GTM. Over 2 tonnes, brakes must be on all wheels and controlled from the tow vehicle, which in practice usually means electric brakes and a controller, plus a breakaway system. Check your compliance plate and current VicRoads information.

Is the Great Ocean Road suitable for towing a caravan?

Many people tow vans along it, but it is a narrow, winding two-lane road with frequent speed changes and busy tourist traffic. Take it slowly, use the pull-over areas to let traffic past, and make sure your brakes and controller are well set up before you go. Check current road conditions and any closures before leaving.

Why did my van battery arrive flat after driving up the Hume?

Common causes are voltage drop in a long, thin charging cable, a smart alternator lowering its output, a blown fuse in the charging circuit, an unwired pin in the plug, or a fridge drawing more than the circuit can supply. A DC-DC charger with properly sized cable fixes most cases, but test the circuit first to find the real fault.

How often should I test my breakaway system?

Before every trip, and again if the van has been parked for weeks. Use the test button or indicator to confirm the battery is charged and the system responds. If the battery won't hold a charge, replace it. A flat breakaway battery means the van's brakes won't apply if it comes off the towball.

Need an auto electrician in Melbourne?

Find local auto electricians and mobile services in the Melbourne directory, or start with your area: Hume, Whittlesea, Wyndham, Maroondah and Yarra Ranges, Brimbank.

Run an auto electrical business in Towing a Caravan Out of Melbourne: Electrical Prep?

• New to Ozautoelectrics? Apply for trade pricing on quality auto electrical parts.
• Already a trade customer? Log in and order parts at your trade price.
• Want more local customers? List your business on this site so drivers in Towing a Caravan Out of Melbourne: Electrical Prep can find you.

Not confident doing this yourself?

There’s no shame in handing it over. A local auto electrician can diagnose the fault properly and get it done safely, especially for anything involving brakes, airbags, hybrid systems or air-con gas.

Find a local auto electrician Or shop the parts and do it yourself