Parasitic Battery Drain

[Roger]

Thoughts appreciated on this little issue I am having, realised following very dead batteries after just a week of standing:

I'm getting 0.45amp draw with ignition off. I pulled all fuses (and relays) one by one to see if I could find the circuit - but nothing. The winches and driving relays/solenoids where fully isolated to disprove them. Any additional wiring I have ever added goes through the 12v additional/supplementary wiring box near the OffSide Battery - again all fused and fuses pulled during checking.

So, with my non electrical brain I have a short to earth somewhere or there are items which remain live and are not part of the fuse box system. Im no electrical expert but I would have thought other than the radio memory there should be nothing live on shutoff for this motor? - 1992 HDJ80

Fuses checked: Main Fuse Box within engine compartment, supplementary wiring box on drivers side, fuses near to the right knee of the driver on the dashboard.

Any ideas?

 

[Steve Wright]

Hi Roger
I cannot think what it could be as I cannot see 1/2 a amp dragging down enough to flatten a battery over a week !
But just a couple of things,
Do you have two batteries wired in parallel ?
Have you checked the batteries them selves (what I would call a drop test)
and sorry to ask (not that I don't believe you) but are you sure it is .45 amp
and not 4.5 amp

 

[Chris]

Half an amp? Hmm that is a lot. I had a similar drain and it turned out to be after market stereo speakers with an amp that was run on house alarm batteries. The drain was the built in charger trying to charge long dead batteries.

All I can think of is, yes, stereo, alarm, tow bar socket perhaps but unlikely. It's probably something that's been added but where is the power being picked up from?

 

[Towpack]

I had a 350>ma drain from the faulty intake heater relay (1HD-FT). I know your truck doesn't have this setup but uses glow plugs. Try disconnecting the main battery feed to these and anything else wired directly to the battery by fusible links and not through any of the fuse boxes.

 

[StarCruiser]

Trailer socket with water in is a good one or even the towing indicator bleeper relay thingy that gets fitted. If they get wet, they can start drawing a current. I've seen one smokingbwhen the bag it was in filled with water and created a carbon track on the PCB.

Radio memory and clock are commonly left connected. You could also be self discharging a battery with the other if one has gone duff if you have two in parallel. You can always disconnect one battery and reconnect it just before starting and see if things improve.

 

[Towpack]

Parked up with alarm set, clock and radio memory etc..etc I get around 30ma draw. If you don't have any more add-ons requiring permanent power, this is the sort of drain you should be getting. Disconnect the earths and the link between the two batteries and bridge it (the + link) with an ammeter to see if there's any current flow between them. If they're normally connected in parallel they should be reasonably well balanced but a duff one pulling the other down should show up.

 

[GuyB]

I had a mysterious draw that would catch me out whenever I left the car for a few days. After much fuse pulling and head scratching, I consulted this forum and read about poorly matched parallel batteries - one drawing on the other. Without the benefit of Towpack's advice, above, I took the plunge on a brace of new batteries - and bingo, the draw fell to just over 20ma.

 

[frank rabbets]

That's a very good point, a drain inside a battery.

 

[Roger]

Thanks for the replys guys, good info - work has got in the way and stopped me looking again, should be on it soon.

I do always pair to the same make and model battery, Ive replaced with a brand new pair and the draw is still the same. Will report back soon!

 

[Dave2000]

Chris mentioned stereo, this reminded me when removing the OE bass speaker in the right hand wing, I needed the space for the water bladder which supplies the shower. I found a box marked 'Motorola', it was wired to a very small dry battery and other cables within the car. The battery connector sparked when I disconnected it, so it was live when the engine was switched off. I took a guess it had something to do with a mobile phone or tracker?

When I found it did not affect the vehicles systems when disconnected, I left it in the garage for awhile, it eventually found it's way in the bin.

If it was individually fused I cannot remember but, if it was, and the installer picked up a feed from behind the fuse box, then it would have had to draw through the fusible links so....................

regards

Dave