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How to… fit a dual-battery system

22 November 2016

A dual battery system is quite an intricate business. A lot of the fabrication is completed even before the system it fitted to the vehicle.

Charge of the dual battery system
If you are going to run a fridge/freezer in your vehicle, a dual battery system is an essential accessory if you don’t want to regularly push-start your vehicle, and if you want your fridge to perform optimally. If you drive a 4×4 with an automatic gearbox and the main battery runs dry, then you are really in a pickle.

This installation makes use of a RING 30amp DC charger. The secondary battery receives its charge via this charger, thus the vehicle’s alternator has nothing to do with this process. The RING DC charger will give whatever charge is required, bulk, float or trickle charge. The new smart alternators of today just cannot charge a second battery efficiently by way of a solenoid system.

When you arrive at your destination, the deep cycle battery used to power the fridge and other 12V auxiliaries can be removed from the vehicle. This way, the vehicle’s standard battery is not drained and you are not left stranded. The RING DC charger is also a regulator and can accept charge via solar panels. The start-up voltage can be set as well as amperage output. You can now manage your dual battery system like never before.


1. The technician inspects the packaged components to ensure everything is present. If all is in order, holes for 12V sockets and plugs are drilled in the connection box with a step-drill.


2. The edges are smoothed over before the 12V sockets and plugs, which will be connected to the battery charger, are inserted.


3. The two plugs and two 12V sockets are secured into place using pop rivets, while the other two sockets are tightened in place using a nut.


4. All components in the connector box are wired. It doesn’t get connected to anything at this stage.


5. Small holes are drilled on the main box, while a larger centre hole is drilled. The wiring that connects the battery to the connector box is fed through here.


6. The connector box is secured to the battery box with pop rivets. This ensures the strongest possible fit.


7. Fuses are connected to the appropriate wires, after the battery is lowered into the main box.


8. All the wires are sleeved, after which it gets marked to indicate its polarity. While this is not only safety-related, it helps to avoid any crossed wires down the line.


9. Battery terminals are inserted.


10. All wires are connected to the terminals of the battery.


11. The chunky battery charger is securely mounted in the lid. Holes are drilled on the lid to feed the wiring from the charger to the battery.


12. The technician ensures that all the wires are properly connected between the battery, the connector box and the charger. The lid is secured on top of the box.


13. The wires between the battery system and car battery are connected and fed to the location where the battery system will be mounted.


14. Finally, the battery system is secured to the vehicle to ensure that it doesn’t move an inch when the going gets tough.

Text and photos: Deon van der Walt