Problem (I think) with Redarc Isolator

[mitch92]

I still say you have the wrong battery on the wrong terminal on the redarc. I think it is measuring the aux voltage to drop in and out, not the main.

Can you swap the cable on the two terminals and try it and see what happens?

 

[maulbeagle]

hi mitch92,
unless my isolator is wired/configured incorrectly internally, then my start battery is definitely connected to the correct terminal (the terminal closest to the lightup section according to Redarc doco).

cheers

 

[maulbeagle]

hi Old.Tony,

when you say

disconnect the isolator's input from the starter battery (which should also disconnect it from the alternator)

is it sufficient to just trip the circuit breaker between the start battery and the isolator ? or do you reckon actually physically unscrew the nut and remove the cable lug from the isolator ?

thanks

 

[Old.Tony]

Undo it. What if the circuit breaker is faulty? We haven't covered that ground yet.

 

[maulbeagle]

no worries. i have actually tested (with continuity test) that the breaker is working.

 

[maulbeagle]

OK test performed.
I got the aux battery down to 12.4 by running the Engel off it.
then tripped the circuit breaker and removed the feed from the starter battery to the "main" terminal on the isolator.
started the car, starting battery started charging at 14.4, aux battery stayed at 12.4

as a further test of the circuit breaker, I left it tripped while I reconnected the starter battery to the "main" terminal on the isolator.
the isolator didn't see the starter battery and kick in until I closed the circuit breaker.

so from this test I guess we can see that the aux battery is truly isolated from the car's circuits, and that the circuit breaker is functioning correctly.

what next ? i'm definitely thinking faulty isolator ?

by the way, thanks heaps to everyone for the help and suggestions.

 

[bods]

So what happens if you trip the breaker while the fridge is connected to it with the car running? Does it then drop the isolator out? I still don't really know why you'd need a breaker between the starter and the isolator, normally it would be on the other side of the isolator...

 

[maulbeagle]

ok so it gets stranger. bods I did as you suggested.
With the car running, and the fridge hooked up, if I trip the breaker between the starter battery and the isolator, the isolator doesn't click, nor does the light go out, and the batteries show they are still connected with a continuity test. However, the voltage on the aux battery drops off to what it was when the car wasn't running !

the breaker is there in case I ever want to completely isolate/disconnect the starter battery from everything else in order to test something or ensure that I can start the car in the middle of nowhere.
Also, Redarc recommend this breaker in their documentation.

 

[Old.Tony]

I'm a little unclear still.

If the engine is running and everything is connected, the aux battery shows that it's getting power from the alternator and if you trip the breaker, it STILL shows it's getting power from the alternator - is that the case?

If it IS, then it sounds like the breaker is intermittently faulty. Next test to remove the breaker from the equation - do the same as your last test, but instead remove the cable from the isolator so that it's completely out of the equation.

Does the aux battery still look like it's getting a charge? It MUST be coming in another path. If you take the output of the isolator off the battery, what voltage do you get from the isolator now?

 

[maulbeagle]

hi Tony, no i don't think that's the case, as the aux battery voltage drops right off when i trip the breaker.

will redo the test tonight and remove the cable from the isolator.

 

[Old.Tony]

If that's the case then don't worry - it definitely sounds like an isolator issue, now that pretty much everything else has been eliminated!

 

[baitfish]

summing up?

so just to run this all through mate,

1. with the CB from the main battery on, you get 14.2 volts on both batteries (car running)
2. with the CB from the main battery tripped you get 14.2 on main but lower on aux, just the charged value (running)
3. when the CB from the main battery is tripped the red arc does not switch
4. even when the AUX battery is run down the redarc stays connected

to my understanding the red arc's main goal is to make sure the main battery is fully charged before connecting the aux battery to charge it. maybe tripping the the CB from the main isolator drops the voltage to quickly and below its measurable threshold and the red arc is lift in limbo leaving it still connected.

If you want to try something else mate, i'd try running your main battery with a load on it to bring it down so its only just charged enough to start the ute (maybe for the test turn the CB off). Also run the aux battery down as well, low as you want maybe 12.1 volts or so.

Now turn the CB back on and start the ute. If the red arc is working it should stay open until the main battery reaches a higher charged voltage it should say in the red arc doco but i reckon it'll be above 13 odd volts. once the main battery it "happy" the aux should start charging. if it does this, happy days, if not it probably is faulty and needs a bench test with a variable voltage supply to see when its switches or if it even switches.

sorry if you've tried this mate, i had a quick re read through the thread and i see anywhere where you has dropped the main battery voltage without just tripping the CB.

 

[baitfish]

how'd ya go mate? sort the problem?

 

[maulbeagle]

hi,
haven't had a chance to run through the last couple of tests, will hopefully do it this weekend and post back.

thanks for the help.

 

[baitfish]

righto mate, best of luck with it.

 

[maulbeagle]

just an update.
checked on the weekend by hooking a charger up in power supply mode to the main cranking battery. with the isolator engaged, and the breaker closed, both batteries showed the same voltage on the dual voltage gauge.
I then tripped/opened the breaker. even though the isolator still stayed lit (and didn't click audibly), the voltage on the auxiliary battery dropped off.
so I'm confident the wiring is correct, with the breaker tripped, the batteries are indeed separated.
also, with the car off, and the batteries joined by the isolator, if I turn on the headlights, after a while the isolator will audibly click and the light will go out, so I'm confident the isolator works as intended.
as someone mentioned above, maybe tripping the breaker just drops the voltage off the isolator too quickly for it to disengage.

hope that's clear (as mud !)