Dead DB isolator

[loanrangie]

Been having problems with my aux. 105ah battery not keeping charge after almost nil usage, replaced the 7 1/2 yo start battery a month ago so its not that. Today managed to get out with the multimeter and check where the problem is, no power led at the power socket in the rear of car and measured further up the line i only get a little over 9V.
Measured terminals of aux and still only 9.26V and same at the output terminal of the Piranha isolator, with engine running i get 14.52V at the start battery and engine off 12.83V.

Time for a traxide upgrade i think.

[Corgie Carrier]

Which pirahna isolator do you have, Nick

I have had one for 16 years and still works great.

Check the earth wire is connected properly.

Hows your ankle going?

[loanrangie]

Which pirahna isolator do you have, Nick

I have had one for 16 years and still works great.

Check the earth wire is connected properly.

Hows your ankle going?

Good Neale, check out general chat - will check the earth.

[loanrangie]

I cleaned up and relocated the earth lead, now with the ignition on but engine not running i get nil voltage at the aux. battery lead as disconnected from battery.
Tomorrow i will test with engine running to see if that makes a difference but i assume that i only need the circuit to be joined to get a voltage reading ?

[Corgie Carrier]

The lead will need to be connected to the battery as the computer can't detect a source so won't allow and current through.

[loanrangie]

The lead will need to be connected to the battery as the computer can't detect a source so won't allow and current through.

Thanks Neale, i charged my aux. batt up and it now reads 13.12V so how can i tell if the isolator is sending the correct voltage to it ?
My alt is putting out 14.52V so should i see this at the output terminal of the isolator and or battery ?

[drivesafe]

Hi Loanrangie, with the motor running and both batteries connected to the isolator, you should see the same voltage on the input and output terminals of the isolator, at the isolator.

[Corgie Carrier]

Is your main battery above 12.8? I think that is the point at which the controller sends all the charge to the aux.

Run a load off the aux battery till it drops and then run the car and you should notice if the controller is working or not.

[Corgie Carrier]

Hi Loanrangie, with the motor running and both batteries connected to the isolator, you should see the same voltage on the input and output terminals of the isolator, at the isolator.

With the pirahna controllers the measurements have to be taken at the batteries as the units are sealed.

[drivesafe]

Hi Neale and thanks, I should have stated test the cables, not the terminals.

With the Pirahnas, I like to push the probe into the insulation of the input and output cables at the isolator.

The idea is to see if the problem is specifically the isolator, or possibly somewhere else in the system.

[loanrangie]

Cant remember the model number but it has external lugs so i can test both input and output terminals. Tests are static since i cant drive and wife doesnt like driving it.

Sent from my GT-I9300 using AULRO mobile app

[drivesafe]

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.

[loanrangie]

Thanks Tim, will test this morning.

Sent from my GT-I9300 using AULRO mobile app

[loanrangie]

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.

[loanrangie]

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.

[loanrangie]

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.

Sent from my GT-I9300 using AULRO mobile app

[loanrangie]

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 .

[Corgie Carrier]

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 :-)

[loanrangie]

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 :-)

Too true Neale i hadnt looked at it that way, i might use it in my kombi.