Dual Battery System is the addition of Auxiliary Battery to operate appliances when there are no main power access, so the starter battery will not be drained.
Dual Battery System is used to run lights, TV’s, Laptops, DVD’s, pumps, fridges, winches, and charge camera batteries and mobile phones. Many of the existing methods used to charge these batteries are now antiquated, and they mostly never did the job very well anyway, neither were they conducive to long battery life.
EITHER a Voltage Sensitive Relay OR a Smart Battery Isolator could be used to isolate the Starter Battery from the Auxiliary Battery, so that during engine startup, the relay will close the circuit to charge both of the batteries and when you shut off the engine, the circuit remain close until the starter battery fall below 12.8V.
Voltage Sensitive Relay advantages:
Waterproof enclosure, some water is not going to stop the VSR from working.
The VSR is rated at 140Amps constant duty.
Surge Protection so it won’t upset the delicate electronics on newer vehicles.
When the VSR is engaged (closed, linking the batteries together) a red LED comes on the top of the VSR .
This VSR consumes no power at all while it is not engaged, i.e. the voltage of both batteries has dropped below 12.8V, and then it consumes only 0.25A when it is engaged.
There are both Single Sense Version and Dual Sense Version, what this means is that if you have a battery charger, or solar power connected to your auxiliary battery, and that battery gets charged enough to hit the VSR set points, then it will allow your charging source to back charge the cranking battery as well, making sure that it’s kept fully charged too, but again, if the voltage drops below 12.8 volts, the VSR will again disconnect (isolate) the batteries.
Wiring Tips
Use 6 B&S (13.5mm²) cable for linking batteries, larger is even better, but could be over-kill on some smaller set-ups.
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