4x4Car Advice

Everything you need to know about 4×4 electrical power options

If you’re going to use your four-wheel drive for off-road adventures, you’re going to need a reliable and abundant source of power for all your electrical gear. These days there are more electrical power options than ever before.

IT’S AMAZING how much gear we take camping these days when we supposedly want to ‘get away from it all’. And a lot of that gear requires a power source, such as the portable fridge, camp lighting, navigation equipment, vehicle sound system, electric winch, driving lights, camera batteries, phone chargers… the list goes on.

Relying on your vehicle’s 12V starting battery to power all of this equipment is a recipe for disaster, and you could find yourself stuck in the scrub after just one night of camping, with a battery that doesn’t have enough voltage left to fire up your 4×4’s engine.

These days there are several power solutions on the market to keep all of your equipment running and charged, while leaving your vehicle’s starting battery alone so it can perform it’s primary function; starting your vehicle’s engine.

Dual Battery Systems

Not so long ago the only viable option for powering accessories was to fit a vehicle with a dual battery system. In its entirety, a dual battery system consists the vehicle’s charging system (alternator), the starting battery, an auxiliary battery, a battery tray or battery box, a wiring loom and a battery isolator.

The auxiliary battery would more often than not be a deep cycle battery, designed to provide a consistent level of power over a longer duration than a starting battery, which is designed to provide short bursts of high power for starting an engine. There are several types of deep cycle batteries; Absorbed Glass Mat (AGM) batteries have glass-mat separators, which help keep the active material on the plates and prevent damage from vibration, and the plates in a Gel battery are held securely in an immobilised gel. For those without much space in their vehicles (and who have a big budget), lithium iron phosphate (LiFePO
4) batteries are a great option. They are about half the size of an equivalent lead acid battery, up to 30 per cent lighter, and have a lifespan up to 10 times as long.

The isolator is designed to ensure accessories draw power from the auxiliary battery, leaving enough charge in the starting battery to fire up the engine when required. In its most basic form the isolator is a manually operated switch, while automatically switching isolators use a switching solenoid, a blocking diode or a microprocessor control system.

Modern automotive electrical systems and battery technology have become far more complex than they once were, so an additional component, a DC to DC charger, has to be added to a dual battery system on modern vehicles to ensure correct battery charging.

Smart Battery Box

An alternative to an in-vehicle dual battery system is the smart battery box, and the great advantage of a set-up like this is that it can be easily moved from vehicle to vehicle.

Many smart battery boxes are designed to accept a variety of batteries, whether traditional lead acid, AGM, Gel or even Lithium LiFePO4 batteries. They usually offer a combination of power outlets including USB ports, 12V DC ports and 240V AC outlets, thanks to the inclusion of a built-in inverter.

To charge the battery, many smart battery boxes can be simply plugged into the vehicle’s 12V ciggy outlet, or charged from a 240V mains source. Some also feature external battery terminals for easy charging, as well as Anderson plug inputs for charging via solar panels.

Some battery boxes also include features such as smart DC to DC chargers, power management screens and low voltage cut-outs to ensure the vehicle’s starting battery is not drained.

Power Packs

For those who want an all-in-one power solution there are a number of portable power packs on the market that come with built-in batteries.

Primus makes a 44Ah Portable Power Pack that houses two 22Ah AGM batteries. Power outlet options include a 12V/15A cigarette lighter socket, a 12V/15A heavy-duty merit socket and a 5V/2A USB port. The pack can be charged via 240V mains power or trickle charged using a supplied 12V DC cable. There’s also an Anderson plug input for charging with a solar panel. Additional features include a digital voltage/amperage display, a low battery warning (light and alarm) and overload protection with resettable circuit breaker.

Waeco also makes a 44Ah power pack with a deep cycle AGM battery cell. It can be charged via 240V AC, 12V DC or solar panel power sources, and has a battery condition LED/test button.

Another brand making a big splash on the portable power scene is Goal Zero, and this innovative company produces a range of power packs. The Yeti 400 has a built-in 33Ah battery and an inverter to provide a 240V AC power source, 12V DC outlet, 2 x USB outlets and a number of charging options. The Yeti 1250 has a huge 100Ah battery that’s claimed to be powerful enough to power a household fridge. Goal Zero also offers a new Lithium range of power packs that are incredibly light and powerful.

Solar Power

These days there are a number of affordable solar panel options on the market for 4×4 travellers.

The most basic fixed solar panels can be permanently mounted to vehicles or trailers, so they’re always there when you need them.

Many portable solar panels have a foldout design, to make them compact when not in use and to maximise surface area when in use. Adjustable legs mean they be angled towards the sun for peak efficiency.

Solar blankets take up even less space when folded, and they as they don’t have a hard frame around their built-in solar panels they can be safely laid out on a vehicle’s roof, windscreen or bonnet without fear of damaging bodywork.

No matter what style of solar panel you opt for, it will need to be equipped with a regulator to safely charge your vehicle’s battery, smart battery box or power pack. Some panels will come standard with a built-in regulator but others won’t, so keep an eye out. You’ll also need an adequate length cable with Anderson plugs to cover the distance between the solar panel and the battery you need to charge.

Last resort

If your portable power system is set up correctly and there are no faults, then you should always have enough charge in your starting battery to fire up your vehicle’s engine… but this is not a perfect world.

Faults occasionally occur, equipment fails, fuses blow and wiring can short, so it’s always good to have a back-up plan, especially when travelling in remote areas.

Thanks to recent advances in battery technology, you can now pick up a small emergency power pack for less than $300 that will fit in your glovebox and provide enough power to fire up all but the biggest petrol and diesel engines.

I always travel with a Super Power Booster in the vehicle. It packs a 20Ah punch, with a start current of 450A and a peak current of 900A, which is enough spark to be able to start a diesel engine up to 4.5-litres in capacity, or a petrol engine up to 7.0-litres in capacity. It weighs just 1.5kg and measures just 17×12.7x10cm, and as well as jumper leads it includes a 12V accessory outlet, two USB power outlets, a pair of LED lights, a digital voltage display and a handy carry handle.

There are a number of emergency power packs on the market and they can really get you out of a pickle.


Dean Mellor

Dean Mellor