Dual Battery System


If you regularly take lengthy trips off-road, it’s likely you’ll take a whole lot of modern conveniences that will make your trip all the more comfortable like fridges and lights, and gadgets that keep you connected such as phones and cameras. Whatever you haul along, chances are they need a lot of battery power to last the distance and here’s where a dual battery system becomes an essential addition to your vehicle. At Voltaic, we are Perth’s leading auto electrical and air conditioning specialists. If you only have one battery in your vehicle it’s unlikely you will be able to power all your appliances and still be able to start your engine for the drive home. A dual battery system will make your life a whole lot easier. Read ahead to find out more.



In simple terms, a dual battery system is where two batteries are used to run everything you might need on an off-road trip. It isn’t as simple isn’t as easy as installing a second battery (which does solve part of the problem with more capacity). If you simply install a second battery without a battery management system attached to it, you could still find yourself stuck with a vehicle that won’t start due to two drained batteries. A dual battery system will isolate the batteries from each other, ensuring your starter battery always has enough power to start the vehicle.

  • Battery one – the starter battery and is essential for starting your vehicle. It is used for all items that can be charged when the vehicle is running such as phone chargers. It’s also connected to the alternator that will ultimately charge both batteries.
  • Battery two – is used for fridges, external lighting, compressors, invertors, and axillary power sockets.


A dual battery system includes two batteries, safety fuses, cables, terminations and connectors, isolator and earthing and grounding.



In today’s modern vehicles, dual battery systems are a little more complex than they used to be. It’s not as simple as installing a 2nd battery, running your accessories off it and wiring in a switch to manually isolate it when the vehicle is off. As such, there are a few of different ways to run your system.

Basic Isolators – similar to a little manual switch which physically connects the two batteries together, however, it is controlled by the ignition. Affordable and effective but the negative is the flat battery will connect as soon as you attempt to start your vehicle, potentially leaving you without enough power for the engine to turn over.

Smart Isolators – the same mechanical switch as the basic isolator but instead of turning on and off with the ignition they’re made to cut in and out at certain voltages. While a they are a more expensive option, they are wise investment as they are able to keep the auxiliary battery disconnected until the starter battery is fully charged. ensuring you’ll always have enough power to get your vehicle going.

DC to DC Chargers

To meet strict fuel consumption and emission targets, many new vehicles are fitted with smart alternators which make it almost impossible to charge an auxiliary battery by traditional methods. Essentially, DC to DC chargers are like a battery charger you’d find at home but they plug into the vehicles wiring making two completely separate electrical systems. This means there is no chance of running the main battery flat by keeping appliances on all night.



When looking for the best dual battery system for your needs, there are some things you should consider:

  • What can your vehicle run? Many cars are locked into running a DC to DC charger, so you may not have a choice as to which system you want.
  • Do you want any extra options? For example, do you want solar input? or maybe the ability to plug your vehicle into a wall at home to charge batteries?
  • Which battery is best? It’s important to consider your mounting options and power usage as that will help determine the best battery type for your system.


At Voltaic, we’re proud to be Perth’s auto electrical experts and can help you will all your battery needs. For professional service and advice, give us a call today on (08) 6454 9916 or visit our Welshpool workshop to discuss your auto electrical needs.

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