Truck and Fleet Electrics in Melbourne’s West and South

This guide is for owner-drivers, fleet managers and workshop supervisors running trucks out of Melbourne's big logistics and industrial areas, from Truganina, Laverton North and Derrimut in the west to Dandenong South in the south-east. It covers the 24V systems most heavy vehicles use, the faults that keep trucks off the road, and how to plan electrical maintenance around a busy depot.

How can we help?

Need it fixed?

Find a local Truck and Fleet Electrics in Melbourne's West and South 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 Truck and Fleet Electrics in Melbourne's West and South?

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

List your business on this site

Where Melbourne's trucks live

Melbourne's freight task is concentrated in a few large precincts. In the west, Truganina, Laverton North and Derrimut are lined with warehouses, distribution centres and transport yards, close to the Western Ring Road and the freeways towards Geelong and Ballarat. In the south-east, Dandenong South is one of the city's largest manufacturing and logistics areas.

The work in these areas is mixed. You'll find prime movers on interstate runs, rigid trucks on metro deliveries, refrigerated vans, forklifts and yard tugs, and plenty of light commercial vans. Many operate long shifts or around the clock, so an electrical fault doesn't just mean a repair bill. It means a missed delivery window, a truck parked in the yard and a driver being paid to wait.

How a 24V truck system works

Most heavy trucks run a 24V electrical system. Usually that means two 12V batteries wired in series, so their voltages add up to 24V. A higher system voltage lets the starter, lights and other loads draw less current for the same power, which means thinner cable and less voltage loss over the long runs in a truck chassis and trailer.

Because the batteries are in series, they behave as a pair. If one battery is weak, the pair is weak, and the good battery gets overworked trying to cover for it. That is why it's normal practice to replace both batteries at the same time, with matching type, size and age. Mixing a new battery with an old one often leads to a second failure soon after.

Many trucks also need 12V for some accessories, such as radios, phone chargers, GPS units and fridges. The safe way to supply them is a proper 24V to 12V converter sized for the load. Tapping 12V off one of the two batteries, sometimes called centre tapping, unbalances the pair and can shorten the life of both. Where it's already been done, a battery equaliser can reduce the damage, but a converter is the better fix.

The faults that stop trucks most often

Fleet electrical faults tend to cluster in the same few places. Knowing them helps you spot trouble at the daily walk-around rather than on the side of the Western Ring Road.

• Batteries that are worn, mismatched or undercharged, often from short metro runs with lots of stops.
• Alternators whose output has dropped, or whose belt or connections are loose. Our guide on whether your alternator needs replacing lists the signs.
• Starter motors worn by many starts per shift on delivery runs.
• Corroded or loose main cables and earths, especially between chassis and engine.
• Chafed wiring where looms pass the chassis rails, cab hinge points and the back of the cab.
• Trailer plugs and suzie coils damaged by stretching, dragging or weather.

Trailer connections and the back of the cab

On a prime mover, the connections between truck and trailer take a beating. Suzie coils stretch and crack. Plugs get dropped on the hardstand, run over or left uncapped in the rain. Corroded pins cause lights that come and go, and on trailers with electronic braking systems, faults that throw up warnings on the dash.

Build a check of plugs, sockets and coils into every coupling. Keep caps closed when uncoupled, hang coils so they don't drag, and replace damaged plugs rather than taping them up. Trailer brake and ABS connections are safety systems, so faults there should be diagnosed properly by someone with the right equipment rather than patched.

Refrigerated vans and trailers

Cold chain work is a big part of the west's logistics business. Refrigeration units add their own electrical demands, including heavy current draws on start-up, standby power connections in the yard, and controllers and sensors that must keep logging temperatures.

If a fridge unit trips out or a van's batteries are flat after an overnight standby, look at the whole system: battery health, charging, the standby connection, and the wiring between them. Any work on the refrigerant side of the unit must be done by a licensed technician. Work on 240V standby power wiring is for a licensed electrician.

Upgrades that pay for themselves

A few changes can cut breakdowns and running costs across a fleet.

• LED lighting, which draws less current, lasts longer and copes better with vibration than globes.
• Battery isolators fitted where drivers can reach them, to prevent flat batteries over weekends and to make the truck safer to work on.
• Properly fused, sized cable for every accessory, so add-ons don't overload factory circuits. See what size cable you need.
• Telematics and fault code monitoring, so problems show up on a screen in the office before a truck stops.
• Quality 24V to 12V converters instead of centre tapping.

Planning maintenance around a busy depot

The cheapest electrical fault is the one found during a scheduled service. Add a simple electrical check to every service: battery test, charging voltage, a look at main cables and earths, and a scan for stored fault codes. Our guide on reading fault codes with an OBD2 scanner covers light vehicles, while heavy vehicles usually need a heavy-duty diagnostic tool. Keep a record for each vehicle so you can see when a battery or alternator is getting tired.

For yards that run around the clock, mobile auto electricians who work on trucks can often do diagnosis and repairs on site, between shifts. Ask whether they handle 24V systems and heavy vehicle diagnostics before you book. Any fault that affects brakes, steering or lights must be fixed before the truck goes back on the road.

Safety in the yard

Truck batteries store a lot of energy. A spanner across the terminals of a 24V bank can weld itself in place and cause serious burns. Disconnect the batteries, or use the isolator, before working on the electrical system, and remove rings and watches. If you smell burning or see smoke from wiring, stop the vehicle and isolate the batteries if it is safe to do so. Our guide on burning smells and smoke from car wiring explains what to do next.

Parts for this job

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

Get it done: get a quoteDo it yourself: shop 24V to 12V converters

Get it done: get a quoteDo it yourself: shop battery isolators

Get it done: get a quoteDo it yourself: shop 24V LED work lights

Get it done: get a quoteDo it yourself: shop truck batteries

Questions Melbourne drivers ask

Should I replace both batteries in a 24V truck at the same time?

Yes, in most cases. The two 12V batteries in a 24V system work in series, so a weak battery drags down the pair and overworks the good one. Fitting one new battery next to an old one often leads to another failure soon after. Replace both with matching batteries of the same type, size and rating.

Can I run 12V accessories from one battery in my 24V truck?

It's done, but it isn't a good idea. Drawing 12V from one battery in a series pair unbalances them, so one gets overworked and both wear out sooner. A properly sized 24V to 12V converter is the better way. If the truck already has accessories tapped off one battery, a battery equaliser can help until you can fit a converter.

Why do my truck's trailer lights keep flickering?

The most common causes are corroded or loose pins in the trailer plug or socket, a damaged suzie coil, or a poor earth at the trailer. Check plugs at every coupling, keep the caps closed and hang coils so they don't drag. If the trailer has electronic braking, have any related warnings diagnosed properly rather than ignored.

Can a mobile auto electrician work on trucks in our yard?

Many can, and on-site work avoids moving a vehicle that won't start or isn't safe. Ask whether they handle 24V systems and have heavy vehicle diagnostic equipment. Make sure the yard has a safe, level spot to work, away from traffic, and that the vehicle can be isolated while they work on it.

Need an auto electrician in Melbourne?

Find local auto electricians and mobile services in the Melbourne directory, or start with your area: Wyndham, Maribyrnong, Brimbank, Greater Dandenong.

Run an auto electrical business in Truck and Fleet Electrics in Melbourne's West and South?

• 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 Truck and Fleet Electrics in Melbourne's West and South 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