Flat battery issue with V8 ute

Submitted: Wednesday, Feb 24, 2010 at 12:14
ThreadID: 76291 Views:3268 Replies:8 FollowUps:7
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Well this is frustrating. Second time in 2 months. Go to start the landcruiser ute and flat battery after only one day of sitting.

The ute has two batteries separated by an electronic isolator. There is an engel fridge sitting on the tray powered from the seconded battery. Both batteries are reading 11.6v which is strange, like they have equalized even though there is an isolator.

I put the battery on charge for 15mins and it has come up to 11.93v but so has the secondary battery. And the isolator is still got a light on saying it is allowing a charge from the primary - but the unit is not supposed to activate until the primary is sitting at 13.4v.

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I have check before the power usage from the primary battery. With everything off and no key in the ignition the only power drain is the alarm system - red flashing light on dash (toyota) and if the door is open even with the interior light off and this is only 0.02amp not really enough to flatten in a 36hr period.

Could the second battery be drained down by the engel and then the isolator fail and allow the primary battery to be discharged.

Even in this discharged state the battery isolator is indicating it is charging - meaning the unit is allowing power to discharge into the secondary battery.

Could this just be a failed isolator. How can I test it.

David

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Reply By: sweetwill - Wednesday, Feb 24, 2010 at 12:45

Wednesday, Feb 24, 2010 at 12:45
hi david.
I know nothing about batteries but I did have an in car phone setup that would drain my battery in two days, took forever to work out what the problem was, cheers bill.
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Follow Up By: Member - Serendipity(WA) - Wednesday, Feb 24, 2010 at 13:04

Wednesday, Feb 24, 2010 at 13:04
Hi Bill

I don't have anything like that in the car. All accessories are tapped off the secondary battery. The starter battery is only feeding whatever toyota has on it from new.

David

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Reply By: Member - John (Vic) - Wednesday, Feb 24, 2010 at 12:46

Wednesday, Feb 24, 2010 at 12:46
Sounds like the isolator is stuffed for a start.
What brand/model is it?

Try disconnecting fridges and other equipment one at a time to locate the source of the power draw.

Could also be one of the batteries is stuffed and is pulling down the other one??

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Follow Up By: Member - Timbo - Wednesday, Feb 24, 2010 at 13:40

Wednesday, Feb 24, 2010 at 13:40
I agree - sounds like the isolator is not isolating the batteries.
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Reply By: PradOz - Wednesday, Feb 24, 2010 at 13:23

Wednesday, Feb 24, 2010 at 13:23
Hi David

Sounds like the isolator is stuck or stuffed. I think i would be disconnecting the fridge and then check what is happenning between batteries. Sounds very much like the isolator is not disconnecting the 2 batteries and the fridge is draining the aux battery which is draining the main battery. I did read somewhere about a quick temporary fix on an isolator but cannot remember what or where it was. Sorry about that, maybe google or somewhere like pradopoint may help (maybe where i read it??) I think a new isolator maybe in order. Over to all the electrical/battery brains on EO for this one. Best of luck with it....
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Reply By: Battery Value Pty Ltd - Wednesday, Feb 24, 2010 at 14:16

Wednesday, Feb 24, 2010 at 14:16
If the isolator solenoid driver indicates 'charging', although the primary voltage is below its switch over point, it's got something wrong within the electronics of the isolator.
I don't know if this could be a problem, but have you checked the ground return path for the isolator electronics?
Is there zero Volts between this ground return wire (measured directly on isolator circuit) and battery minus?
And what's the positive on the isolator electronics like?
I'm speculating that the electronics could get confused by too little supply voltage...any spade connectors on it you could check?
Or, a bad contact at the battery voltage sense wire connectors (if it has one)?

Wish you luck!
Best regards, Peter
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Follow Up By: pf11 - Wednesday, Feb 24, 2010 at 15:23

Wednesday, Feb 24, 2010 at 15:23
Not sure if this will help.....I had an issue with my 3 battery set up immediately after I put my truck into a shop for Diff Locks to be fitted. I found similar readings as yours from all 3 batteries and once the engine was going the voltage improved but only slightly. It turned put to be the fault of the Diff Lock Fitters as when they installed the compressor, they forgot to re-connect my earth strap from the second battery. A simple oversight by the fitter had me looking in all directions. I re-connected the strap to the chassis and all back to normal.

Cheers: Phil
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Follow Up By: Member - Serendipity(WA) - Wednesday, Feb 24, 2010 at 19:24

Wednesday, Feb 24, 2010 at 19:24
Hi Peter

Thanks for your advice & everyone else.

It is 40deg outside just now but I did go out and park under a tree and pull the battery and the isolator out. Strange thing is the isolator retained the orange indicator light even after being disconnected from the battery. Only when I started to take the cables off the unit and wiggled the bolt leading to the second battery did the indicator light shut of with a click.

I am guessing there was a bit of corrosion in that connector and the unit was missreading the battery status.

When I cleaned it all up and even put a smear of never-seize on the threads the unit acted strange. When all the wires are back in place and then I connect the large positive to the primary battery (which has been recharged now) the orange indicator light goes on as expected to start charging the secondary battery. But if I remove the cable from the primary battery the orange indicator light will stay on. Only when I removed the positive from the secondary battery did it go out again.

I do not understand this electrickery and for the most just go along with it.

Does this sound like a properly functioning unit.

David

Ps Time will tell if the second battery gets charged up and the unit shuts down.

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Follow Up By: Battery Value Pty Ltd - Wednesday, Feb 24, 2010 at 20:03

Wednesday, Feb 24, 2010 at 20:03
Hello Serendipity,

it looks like the unit is designed to accept power from both primary and secondary via two internal blocking diodes.
A configuration like this would have the advantage of providing immunity to primary/secondary battery contact reversal, i.e. it wouldn't matter in which order the two batteries are wired up to the first and second solenoid contacts.

Or, it was wired up the wrong way, in which case the supply current only came from the second battery originally, but then from both batteries after the solenoid got powered on.

Nevertheless, the fact that the solenoid was still receiving power, indicated by the charge light (and the audible click on disconnection), while the voltage was way below the threshold makes me think the isolator circuit is knackered.

And because of this defect, the solenoid current (a couple amps?) would drain both batteries at the same time via the two blocking diodes, and/or the closed solenoid contact.

Maybe you can get a replacement only of this circuit, because the solenoid seems to be working ok....

Best regards, Peter

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Reply By: The Boss - Wednesday, Feb 24, 2010 at 17:31

Wednesday, Feb 24, 2010 at 17:31
Yeah have to agree, sounds like the isoltaor playing up.

Little bit OT, but thats a hell of a cobweb there with your wiring, and i cant spot a fuse anywhere. Your alot gamer then i am.
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Follow Up By: Member - Serendipity(WA) - Wednesday, Feb 24, 2010 at 17:53

Wednesday, Feb 24, 2010 at 17:53
The cobweb of wires looks bad but most are just going to 12v outlets on the back of my ute. The engel has its own fuse. The water pump doesn't draw much at all. Others are for lights over the tray. I try to keep down connections so as to no lose so much current.

Yes I should fuse the wires just in case there is one that gets worn through or broken and starts arcing against the body.

I have it on my very long list of things to do.

Thanks for the reminder I might take this opportunity to move that item up the list a bit.

David

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Reply By: Dennis Ellery - Wednesday, Feb 24, 2010 at 18:02

Wednesday, Feb 24, 2010 at 18:02
Hi David
I have a V8 Troopy that developed an electrical leak in the winch loom after about 18months use. (Toyota supplied) It used to flatten the starter battery
I tracked the leak down with an amp meter and Toyota replaced it under warranty.

It appears that your solenoid is activated.
It’s not difficult to test your solenoid but not an easy option to explain over the internet.
It could be incorrect wiring and may be the fault of the person who installed the solenoid.
Take it to a sparky and get it checked out.
AnswerID: 405783

Follow Up By: Member - Serendipity(WA) - Wednesday, Feb 24, 2010 at 19:26

Wednesday, Feb 24, 2010 at 19:26
Hi Dennis

I have carefully checked the current - amps coming out of the primary battery and found there is very little happening when the car is parked up with the key out. There is a minor discharge related to the onboard security and if a door is left open even with the internal light off a larger discharge - still minor.

David

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Reply By: Member - Graham H (QLD) - Wednesday, Feb 24, 2010 at 22:06

Wednesday, Feb 24, 2010 at 22:06
This is meant in a light hearted way so

Maybe one of the rats in the nest of wiring has chewed one.

I thought mine was a bit rough but nothing like that.

You are really looking for trouble with them like that and no fuses anywhere.


But a Redarc off Derek and fix the problem.



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Reply By: Member - Phil G (SA) - Wednesday, Feb 24, 2010 at 23:22

Wednesday, Feb 24, 2010 at 23:22
David,
With all due respect, that is a pretty impressive bowl of spaghetti!! Is there a chance than one of those wires is linked between the two batteries? i'd check that out before I checked the isolator.
Secondly, one of your batteries may have dropped a cell, causing the voltage to read 11.9. But you need to isolate them to find that out.

Cheers
phil
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