Dual Battery System Set Up using the Intervolt DCC Pro

Using the Intervolt DCC Pro for Dual Battery Systems

Dual battery systems are installed and used in a large number of different applications and for a variety of reasons. You will find some of these applications in 4WD’s, camper/caravans, boats and motorhomes used for mobile power. This is not a new idea and has been around for a while in different forms. The main reason for a dual battery system in a vehicle is to ensure not to run a main or starting battery flat whilst still being able to supply a constant power source to run auxiliary equipment such as portable fridges, lighting or for charging our mobile devices and accessories. For older vehicles, these systems can be a simple setup, but it can get a little complicated for later model vehicles and usually aren’t just a simple hook up and run scenario.

Different battery types also require different charging voltages and methods. A standard lead acid (Main starting battery) will happily charge fine off your alternator but to maintain an AGM or GEL Deep Cycle battery correctly requires different charging parameters and will sometimes require extra charge boosting to correctly maintain the voltage these batteries like. We run through the two main types of basic dual battery system setups below.


Main / Starter battery, auxiliary battery, manual circuit breaker and fuse box

Older Vehicle Setups

Components of dual battery systems generally consist of the main/start battery, an auxiliary battery, some form of switch or isolator, fuses and cabling. This basic range of products are most commonly used on older cars to connect and control the charging process. A Voltage Sensitive Relay, commonly known as a VSR, is used as the switch or isolator in these systems and allows the main and auxiliary batteries to be connected for charging, managing and protecting the condition of the two batteries. It will connect and disconnect at certain pre-set voltages depending on what voltage the main battery is reading at the time.

Usually you aren’t able to change these voltage settings. It is a pretty straight forward setup with a KT Cables VSR located between the two batteries and usually closer to the main battery. The KT Cables VSR unit will also isolate or disconnect the main battery from the auxiliary battery if the main battery voltage is below a certain point in order to preserve a starting charge in the main battery and therefore, if all works properly, not leave you stranded.

Newer Vehicles Setups

With the advent of computer controlled variable voltage alternators we have had to move to far more intelligent methods of charging a second or auxiliary battery. These new methods will undoubtedly comprise of running a DC–DC charger, which in most cases replaces a VSR. A variable voltage alternators cuts in and out, depending on the vehicle loads and power requirements, and will usually not supply enough charge to maintain both the main and auxiliary batteries. Therefore a DC-DC charger is added to provide a constant boost charge to the auxiliary battery as long as the main battery has a suitable amount of charge. There are a number of these on the market, of which we have chosen the Intervolt DCC Pro 12v 25Amp charger as part of our range of products and to add into this circuit. The advantages we believe in using the Intervolt DCC Pro charger is the simplicity of hook up, setup and monitoring as well as being IP67 rated. It also acts as an isolator between the batteries and can be programmed to only operate when the ignition is turned on. The Intervolt DCC Pro charger has a MPPT solar regulator integrated into the unit, providing a power supply solution for when you’re parked up. It also comes complete with a display monitor enabling you to keep an eye on battery voltages of both batteries, amps the Intervolt DCC Pro is supplying the Aux battery and Watts being supplied by the solar panel as well as type of battery and what mode the Intervolt DCC Pro is charging in(Bulk, Absorb and Float). A very intelligent solution.

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The Setup


As you can see in the diagram, we have included all required parts to hook up a dual battery system with the Intervolt DCC Pro DC – DC battery charger. This includes the installation of Mega fuses or resettable Circuit Breakers to protect both the batteries and the Intervolt DCC Pro. You will require a minimum of 60A fuses or circuit breakers (Always read the instruction manual that comes with any connecting device you use to ensure you are using the correct size fuses). You should always try to mount the Intervolt DCC Pro as close to the Auxiliary battery as possible, this reduces any voltage drop, whereas mentioned before a VSR should be mounted close to the starting b attery for correct operation. Another consideration to take into account is the cable sizes. This will depend on the “length of run” of the cables based on the location of the batteries, as well as whether you are running a DC-DC charger or VSR. The Intervolt DCC Pro instruction manual is a must to follow when setting up the unit and gives valuable information in regards to the cable sizes required when hooking up the unit. You will also need to consider how you are going to connect external solar power to your vehicle and the Intervolt charger. I have found the KT 50A Trailer Plugs – KT70027 (As pictured) to be an excellent method, they are sealed from dirt, mud and insects when not in use.

Once you have your dual battery setup fitted and connected and your Intervolt DCC Pro (If you are using one) programmed to suit your systems components, you can hook up any of your auxiliary accessories, particularly your fridge so you can start enjoying a few cold drinks with the peace of mind that you have hours of power at your disposal.

Dual Battery Set up

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DCC Manual

Intervolts Standard Wiring Diagram for Intervolt DCC Pro ( Main / Aux Battery )

For more information, or to find your nearest KT Stockist, please contact us using the below contact form or call us on 1300 559 953



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