Planning your Dream 4WD Power System

When your 4WD travels take you on off-grid adventures, you need a DC power system to keep the good times rolling. We step you through the essentials, so you can plan and put together your dream power system.

1. Auxiliary batteries

The first step is to buy a deep-cycle AGM battery. AGM batteries charge up faster than conventional batteries, they’re maintenance free, and they’ve got a longer service life and a low self-discharge rate. They need to be charged at a higher rate (14.7V) and cost a little more, but it’s an investment worth making.

When you’re deciding what size battery you need for your 4WD or camper trailer think about:

  • How much power your appliances will draw?
  • How long you want to run your appliances every day?
  • How many days you’ll be away from mains power?

Two Examples

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  • Baintech TBB Deep Cycle 12V 110AH AGM Battery. Learn more.
  • Ideal for people who are lighter power users, run a few appliances, and like to get away for a weekend.
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  • Baintech TBB Deep Cycle 12V 220AH AGM Battery. Learn more.
  • Ideal for people who are heavier power users, who may have critical appliances like CPAP machines and who like to get away for longer trips.

2. DC-DC charging

If you’re planning adventures that will take you off-grid for a weekend or more, a DC-DC charging system can ensure you have reliable power right through to the end of your escape.

A DC-DC charging system will recharge, maintain, and extend the life of your auxiliary battery or batteries while you’re on the move, via an alternator, or when you’ve set up camp if you’ve got solar.

When you’re buying a DC-DC charging system think about:

  • Whether you want a portable or inbuilt DC-DC power solution?
  • Whether you want to charge batteries from an alternator or solar or both?
  • Whether you need a charger with a special mode for AGM batteries?
  • Whether you need a charger designed for smart alternators
  • What type of charging capacity / power do you need?

Two Examples:

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  • Baintech PowerTop V1Learn more.
  • Ideal for people who want a portable power system, that they can locate near their campsite, lend to a mate or take out of their 4WD when home (to charge up and store away).
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  • CTEK D250SA (20 Amp DC-DC charger) for $499.43 Learn more.
  • CTEK SMARTPASS 120 (power management system) for $531.25 Learn more.
  • Ideal for people with service batteries larger than 100Ah, where they want to be able to charge, manage and control their power.

3. Meters and monitors

Meters and monitors let you take charge of your power system and stay in full control; you’ll always know how much power you’ve got so a flat battery will never leave you stranded, or cut short your next adventure.

Meters give you information about the status of your battery (volts), and how much power you’re drawing from your battery at any given time (amps). You can use this information to work out how much capacity your battery has left, and evaluate the power needs of individual appliances.

Charge 6V battery 12V battery 24V bank 48V bank
100% 6.37 12.73 25.46 50.92


6.31 12.62 25.24 50.48
80% 6.25 12.50 25.00 50.00
70% 6.19 12.37 24.74 49.48
60% 6.12 12.24 24.48 48.96
50% 6.05 12.10 24.20 48.40
40% 5.98 11.96 23.92 47.84
30% 5.91 11.81 23.62 47.24
20% 5.83 11.66 23.32 46.64
10% 5.75 11.51 23.02 46.04

Monitors give you more advanced information about volts, amps, percentage of energy consumed, and the amount of time you can continue to support the current load. You can also set an audible alarm for a specific battery voltage, and take the guess work out of the calculations.

Two Examples:

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  • Baintech Volt and Amp Meter. Learn More
  • Ideal for people who are happy to do the power calculations themselves.
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  • Victron BMV702 Monitor. Learn More
  • Ideal for people who want more advanced information, that’s easy to understand and where it is more critical they don’t get a flat battery.

4. Inverters

An inverter lets you power some of your 240V appliances while you’re away, but before investing in an inverter check that your battery has the capacity to power your appliances.

When assessing the power you need from your battery and the size of your inverter make sure you:

  • Identify how much power each appliance will use
  • Work out how long you want to run the appliances
  • Estimate the total (watts) of power needed for all your appliances

The rough guide below shows estimated Watts and Amps for common appliances:

Appliance Estimated Watts DC Amps (12V batteries)
Small Air Compressor



Blow Dryer



Small Microwave



Juicer/Blender/Game Consoles






CPAP Breathing Machine



Laptop Computer



Portable Stereo / Play Station



Charger / Mobile Phone /Camera / Camcorder



Some appliances need more initial power to get them started, and the start-up load of an applia
nce will determine if an inverter has the capability to power it.

If you want to run more than one appliance at the same time, then choose an inverter based on the total Watts for all the items you want to run.

Once you’ve worked out the total wattage add 20% to 30% to the total to calculate your minimum inverter power requirement.

Two of our most popular inverters:

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5. Solar power

More and more Australians are using solar to recharge batteries when they’re on the move. It’s a smart choice since solar has a long lifespan, power generation is quiet, and its low maintenance compared to a generator.

Solar options for 4WDs (and camper trailers) include:

  • Hard or flexible fold out panels that can be moved around throughout the day to maximise sunstrike; they need to be stored, then set up and taken down every time you make and break camp, which might be too much effort at the end of a long drive
  • Solar blankets which are lightweight, compact and flexible enough to follow the sun. They’re also easier to set up and pack up, and kilo for kilo they have a higher power output than traditional folding panels

Getting the maximum power output from your system means thinking carefully about each stage of the set up, so remember:

  • The size and type of solar panels determines the initial energy being fed into the system
  • The charge controller moderates the flow of power to the battery. A simple ‘shunt controller’ will switch off after a pre-set voltage is reached. A maximum point power tracker (MPPT) makes the current taper off gradually and can mean a 10 to 20 percent power boost from one panel.
  • Batteries are rated on amp-hours; the higher the amp hours the more power can be stored.

Two of our most popular solar solutions

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6. Accessories

We still need to power up the essentials of modern life on 4WD adventures, and that means smart phones, laptops, tablets, fridges, stereos, cooking appliances, CPAP machines and more.

4WDs don’t have enough sockets to plug in all the devices we need on our adventures these days, but Bainbridge Technologies has sockets and power panels to keep your devices charged, so your beer is always cool and you are always connected.

BainTuff sockets

BainTuff range is durable, robust and safe and designed to perform without fail in the toughest Australian outdoor conditions. The BainTuff range comes in a Ciga socket, Engel socket and USB.
Learn more.

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Power Panels

The Baintech Universal Power Panel powers multiple devices, it also lets you manage your power usage (with an LCD backlit volt meter), protect your electronics (with fused circuit protection), safeguard your battery (with auto low voltage disconnect) and dig deep into your battery when you need it (with auto disconnect bypass). Learn more.

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  • Baintech Universal Panel 5.0 – Ciga, Engel, USBLearn more.

Visit our shop to learn more about DC products to power up your next 4WD Adventure. To enjoy a 10% discount on our products (excluding CTEK) enter the code “DREAM”.

Enjoy more good times on your next adventure.

Michael Tyrrell

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