This test can be done on any VSR or electronic isolator including brands such as
Redarc, Surepower, Projecta, Piranha, ARB etc. It is recomended to test the isolator
every season or if you suspect any charging issues with your aux battery.
When testing the isolator we are looking to make sure the isolator switches on when
the engine is running and that there is no excessive voltage drop through the isolator.
It is normal to have a voltage drop when the aux battery is flat or there is a load
on the aux battery. After short drive or 30 to 60 minutes at fast idle the voltages
of the batteries should be similar with no serious voltage drop across the isolator.
A voltage drop of approximately 0.2V is acceptable after a short drive or timed fast
We have created a animated gif picture below to show the test, please watch the test
for a minute or two and you will easily be able to test your isolator yourself.
You will need a digital voltmeter to do the test.
Should you have a high voltage drop or the isolator does not switch on further testing
will be required.
If you need to restart the test, switch the car off. Switch the headlights on until
the isolator switches off at approximately 12.5V and then do the test again.
The isolator shown is our new Bi-directional isolator which has voltage sensing circuits
on both the main battery and the aux battery terminals. Perfect for systems with
solar connected to the aux battery. The isolator features delay timers for on and
off to prevent excessive loads on the alternator and to prevent isolator cycling
as loads are switched on. The Bi150 is also directly compatible with our dual battery
monitor. For more detail on the Bi150 click here.
Note: If you already have one of our dual battery monitors you will know that this
test can be done on the monitor from the drivers seat at any time.
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