Dual Battery Systems
Accelerate Auto Electrics supply and fit a wide variety of Dual Battery Systems to suit all makes and models of vehicles.
We can fit dual battery systems to 4WDs, caravans, camper trailers and regular cars.
Are you wanting to get off the beaten track but don’t have enough power to run all your accessories like a portable fridge or freezer, winch or even charge your phone?
Do you need backup power in case your primary battery dies when you are in a remote part of the country and can’t call a mate to come and jump start you?
If you answered yes, then a Dual Battery System might be just what you need…
Keeping Your Cool
The typical 4WD traveller has a fridge in the back, filled with food and beer. Failure to keep beer at the right temperature is disappointing, but failure to keep food at the right temperature can be health-threatening.
The best way to ensure your fridge will run overnight when the engine isn’t operating is with a deep-cycle battery. If the fridge is connected to the deep-cycle battery all the time, it will keep the power flowing as long as it has sufficient charge.
How do they work?
Dual battery systems are designed to ensure the deep-cycle battery is charged, without the chance of the vehicle’s starting battery being discharged.
There are several ways of achieving that, from a simple, manual rotary switch to mini-computerised electronic devices. Before the arrival of electronic dual battery isolators, the state of the art solution was a solenoid device and which are still popular today.
Function of the Isolator
The function of an isolator is to disconnect the deep-cycle battery from the vehicle’s starting battery when the deep-cycle battery is operating the fridge. It also must maintain that disconnection when the engine starts, until the starting battery is fully charged, after which it allows charging current to flow to the deep-cycle battery until it’s charged.
The latest electronic devices take the process a stage further, by monitoring both batteries and adjusting charge rate to suit battery age and condition.
Some dual battery isolators have a function that allows the deep-cycle battery to act in conjunction with the starting battery, to boost starting power should the starting battery drop voltage.
That system functions well where cranking loads are small, but a dead-flat starting battery may not receive enough power from the deep-cycle battery to start a large-capacity diesel engine. You can then be stuck with a dead engine and a dead fridge.
Some electronic isolators with override have a block on the dual connection that prevents draining the deep-cycle battery if the starting battery has too little power to effect a dual-battery start.
However, the message is clear: you need some form of backup battery charging with every dual-battery installation, to make sure you won’t get stranded in the bush.
Do It Right
As important as the type of isolator you select is the way the dual-battery system is fitted. Traditionally, a second battery goes into the engine bay, but most of
engine bays are full of other stuff. Also, today’s engine bay temperatures are higher than those of yesterday and batteries hate too much heat – particularly absorbed glass mat (AGM) types.
A deep-cycle battery, or a power pack and most types of isolator can be fitted into the back of a
or ute, but don’t scrimp on the size of cable connecting the starting battery to the auxiliary, or you’ll suffer from voltage drop. You can buy protective cases for deep-cycle batteries that have to be stored inside vehicles.
A simple isolator won’t be enough for many modern 4WDs that have electronically regulated alternator outputs. What’s required is a purpose-designed auxiliary battery DC-DC charger.
All connections, including earth terminals, must be made of top quality material and securely fastened with
nuts. A small, loose connection will cause big trouble.