HomeServicesDual Batteries & 4WD Electrics
The fridge drains the start battery overnight, or the camper's power is gone by day two. Our Logan auto electrical workshop handles dual battery installation in Logan, fitting a system so the engine always starts and the fridge keeps running. Tell us what you run and tow, and we size the system around it.
As a 4WD auto electrician, we build auxiliary battery setups around a DC-DC charger, which smart alternators need. You choose lithium or AGM. We add fridge outlets, solar input, light bars and UHF so the wiring is done once and done properly. We fit gear from REDARC, Enerdrive, Projecta, Victron and Narva, and we pick the unit that suits your load. Every battery and charger goes in as part of a fused, tidy system that is easy to understand and easy to service later.
Each setup follows how the vehicle is used, from the daily M1 run to the Gold Coast hinterland and the Keyhole Track on Straddie, which needs a vehicle ferry from Cleveland. Drop the vehicle at our Logan-based workshop near Slacks Creek and Springwood at a time you book. Call 07 3566 2108 or use the quote form on this page to start.
These are the common jobs for tourers, tradies and campers. Most vehicles need a mix of them, and we wire it as one tidy system.
We fit the second battery under the bonnet, in the tub, in a canopy or in a drawer system, wherever it suits your vehicle and load. The battery is mounted securely so it can't shift on a corrugated track. We size the cable for the current it carries and keep runs short, so voltage doesn't drop on the way to the fridge. Both ends of each cable are fused and labelled, so you can trace the circuit if you add gear later.
Many newer vehicles have smart alternators that drop their output when the start battery is full. A basic isolator then charges the auxiliary battery poorly. DC-DC charger installation fixes that, because the charger manages the charge from the alternator. We also fit a solar regulator (MPPT) so panels can top up the battery while you're parked at camp. The regulator is matched to the panels you carry and the battery you chose, so nothing gets overcharged.
A camp fridge needs a dedicated, fused feed with enough cable to run it without voltage drop. We wire fridge outlets, USB sockets and Anderson plugs where you will actually reach them, in the tub, canopy or cab. Everything runs off the auxiliary battery, so charging phones and running the fridge never touches the start battery. A fused distribution point keeps the outlets organised and separate from the vehicle's own wiring.
We wire LED light bars and driving lights through a relay, with a switch in the cab and a harness that's fused at the battery. The relay carries the heavy current so your switch doesn't have to. Cables are routed and protected so they stay clear of heat, moving parts and sharp edges, and the connections are sealed against dust and water. The harness unplugs easily, so the bar can come off if you ever sell the vehicle.
We install UHF radios with a proper power feed, a tidy antenna run and the handset where it's easy to reach. For canopies we add internal lighting and power, switched from the cab or the canopy itself. The wiring is fused and clipped down so it survives a rough track, and so you can trace it later if something needs changing. A UHF is only useful with a clean signal, so we check the antenna mounting and earth before the vehicle goes back to you.
Every install follows the same order. It keeps the job predictable and means the setup suits the way you actually use the vehicle.
We start by listing what you'll run: the fridge, lights, devices and how many days you'll be off-grid. That load decides the battery size, the charger and the cable. Getting this right first avoids a battery that's too small or a charger that can't keep up.
Next we choose lithium or AGM for the auxiliary battery, and a DC-DC charger or an isolator to charge it. Your alternator type and how you travel both feed into the choice. We explain the trade-offs so you know why we recommend what we do.
We mount the battery securely, run correctly sized cable and fuse every circuit close to its source. Connections are crimped and protected, and cables are routed away from heat and moving parts. A fuse in the wrong spot is a common fault in rushed installs.
Before the vehicle leaves, we confirm the auxiliary battery charges from the alternator and, where fitted, from solar. We check the loads run as expected. Then we walk you through the battery monitor and how to read it, so you can see what's left in the bank.
Book the vehicle in and we'll test it and price the repair before any work starts.
Two choices shape every dual battery system: the type of battery, and how it gets charged. Here's how we weigh each.
Lithium (LiFePO4) batteries are lighter and give you more usable capacity from the same rated size. AGM batteries are heavier, and you shouldn't drain them as deeply. Lithium needs a charger set up for it, while AGM is more forgiving. Heat matters for both, so where the battery sits in the vehicle counts as much as which one you pick. We talk through weight, capacity and charging with you before we order anything.
A battery isolator simply joins the two batteries when the engine runs. It works on older vehicles with a steady alternator output. Smart alternators vary their output, so an isolator can leave the auxiliary battery undercharged. A DC-DC charger manages the charge properly, which is why we suit it to smart-alternator vehicles and lithium setups. It also stops the auxiliary battery pulling the start battery down when the engine is off, so you keep a battery that starts the car every morning.
Tourers leaving Logan head south on the Pacific Motorway, then on to the Gold Coast and northern New South Wales. The Mount Lindesay Highway takes you south-west to the Queensland-New South Wales border. To the east, Straddie is reached only by ferry from Cleveland, and the Keyhole Track at Main Beach is one of the top 4WD tracks near Brisbane.
Weight matters too. Queensland Government guidance says supplementary batteries count when assessing a tow vehicle's towing load, along with bull bars, long-range tanks and roof racks. Worth knowing before you add a second battery to a vehicle that already tows.
Heat is the other factor. NRMA advises that car batteries are very sensitive to heat and that temperatures over 30°C can shorten a battery's life. That's general motoring advice, but it's why we think hard about where your batteries are mounted.
4WD electrical work should be built to be used hard. These are the standards we work to.
We match the battery and charger to the load we worked out with you, not to a standard kit. A weekend fridge setup and a week-long outback rig need different systems. Getting the size right means you're not carrying weight you don't need, or running short on day three. That is the point of working out the load first.
Every circuit has a fuse sized for its cable, fitted close to the power source. Cables are protected where they pass through panels, run near heat or sit under the vehicle. Connections are crimped and sealed. That limits the risk of a short circuit or cable fire on a rough track.
A battery monitor shows state of charge, so you know how much power is left before you need to drive or sit in the sun. We show you how to read it and what the numbers mean for your setup. Then you can plan your camp power rather than guess.
No two setups are the same, so we don't quote from a price list. The cost follows what goes in and how much work it takes to fit. Send us the vehicle and what you want to run, and we'll give you a free written quote. The form beside this page is the quickest way to start.
Lithium and AGM batteries are priced differently, and so is every capacity. Bigger amp-hour ratings suit longer trips and heavier loads.
An isolator, a DC-DC charger and a solar regulator are different parts at different costs. The charging method also decides how much wiring the job needs.
An under-bonnet mount is a different job from a canopy or drawer install. Longer cable runs and custom brackets add time to the fit.
Fridge feeds, USB and Anderson outlets, light bars, UHF and an inverter each add parts and labour. Tell us the full list so the quote covers it.
You usually need a DC-DC charger for a dual battery system if your vehicle has a smart alternator or you're running lithium. Smart alternators vary their output, so an isolator can leave the second battery undercharged. Older vehicles with a steady alternator can sometimes get by with an isolator.
A dual battery is charged from the alternator while the engine runs, through either an isolator or a DC-DC charger. Solar panels can add charge when you're parked. Many touring setups use both, so the battery tops up on the drive and at camp.
How long a dual battery runs a fridge depends on the battery's capacity, the fridge's draw, the outside heat and any solar input. A hot day makes the fridge work harder. We work through those factors with you so the setup matches your trips.
Lithium batteries are lighter than AGM and give you more usable capacity. They need a charger set up for lithium, which is another reason a DC-DC charger suits them. AGM batteries are heavier and shouldn't be drained as deeply.
The right size lithium battery for a 4WD comes from your daily load and how many days you'll be off-grid. Add up what the fridge, lights and devices use, then plan for the days between charging. We do that sum with you at the start of the job.
You can install more than one auxiliary battery if the batteries are matched and the charging is set up correctly. The extra weight counts, too: Queensland Government guidance says to include supplementary batteries when assessing towing load. We talk through the trade-off before adding a second battery.
You can run an inverter off a dual battery for small loads, as long as the cabling is heavy enough and the circuit is fused. Inverters pull a lot of current, so we size the inverter to what your battery can supply.
Call 07 3566 2108 or send the form to plan your dual battery fit-out. Tell us the vehicle and what you want to run, and we'll take it from there.