Thread: Dead DB isolator

Hi again, you don't have to drive anywhere to be able to test to see if the isolator is working.

First measure the voltage of both batteries and then start the motor and let it idle for a minute.

The voltage at the isolator's input side will rise to over 13.7v and this should cause the isolator to cut-in ( turn on ).

If the voltage on output side is not up near the same voltage as the input then it is likely the isolator is cactus.

Thanks Tim, will test this morning.

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Got around to checking the isolator this morning (DBE100 S ) main battery at 12.53 and with engine running i get 14.75 at the main battery and input to isolator, isolator output is 12.22 which is what the aux. battery is at with engine off.
I charged the aux. up last week to 13.2 and it has been driven once for about 10 mins since and no load on the battery apart from a single led on the waeco raps power socket.
From Tim's post above i assume the isolator isnt working, i might try another earth location just in case.

Idled for 10mins and isolator output didnt rise above the current charge of the aux. batt @ 12.22V , new isolator time i think.

I think i have found the problem, decided to cut of the existing connectors to remove the unit then decided to try with the bare wires direct to the battery terminals.
I now have the internal relays closing after its been idling for over 10mins which i confirmed by opening it up so i can see them working and a quick look over the soldering which looks fine so now just to crimp on some new connectors and refit.

Got the wife to use my car to collect kids thinking that 10 mins should be enough for the isolator to kick in but find the output is no where near the input of 14.65v at 12.2v.

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For closure, tonight i was replacing the supposedly dead isolator with a replacement unit and being just on dusk we noticed some sparking from the circuit beaker.
So looks like it was the breaker failing and not the isolator, seems i have a spare now .

At least you caught it before the breaker set fire to your car. Nothing wrong with an extra isolator, now you have a reason to get another landy :-)