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Premium Member
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Discussion Starter #1
Hi dudes,

Hoping somebody might be able to advise me about a mystery battery draining issue on my 2003 T4 (ex-AA) 2.5 (ACV). I cannot find a cause for my persistent flat battery issue.

Drives well and starts strong but if its left for more than 4-5 days, its totally flat!

Have just put a brand new battery in it and cleaned up the terminal connects and the earthing contact from the battery. Still the same old problem, arghhh.

Any ideas on what I should do next/how to find the fault?

I seem to have a faulty coolant sensor (intermittently alarms even though levels good). Could a faulty sensor cause a battery drain?

Also, wondering if the old AA immobiliser is somehow involved (although I thought I'd removed all elements of this).

Cheers
 

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Full of Cr*p....
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8,877 Posts
If you have a glove-box, check the light is not staying on all the time!

If you have a faulty coolant sensor, check to make sure the auxiliary water pump is not running all the time!

After that, it's a matter of getting a multimeter on current range, connect between + battery contact and the cable (remove the cable from the battery!).
DO NOT turn on the ignition!!!!!!
See how much current is flowing and remove (refit) one at a time to see which circuit is taking the current.
 

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Premium Member
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176 Posts
Discussion Starter #3
If you have a glove-box, check the light is not staying on all the time!

If you have a faulty coolant sensor, check to make sure the auxiliary water pump is not running all the time!

After that, it's a matter of getting a multimeter on current range, connect between + battery contact and the cable (remove the cable from the battery!).
DO NOT turn on the ignition!!!!!!
See how much current is flowing and remove (refit) one at a time to see which circuit is taking the current.
Thanks for the advice dude, really helpful.

so, the battery was showing 10.65 after 1 day of installation. I then did the test you recommended and the draw was showing as 0.57! I removed 1 fuse at a time and retested between and the draw continued to show but decreased each time (is this normal for the test). After I’d finished the whole row of fuses the draw had gone down from 0.57 to fluctuating between 0.3 and 0.5? I then found a separate fuse for the stereo and when I removed this the reading went down to 0 so I’m thinking it was the stereo. I’ve taken the stereo out and the reading has stayed at 0. Then went for a 40 minute drive and briefly for about 1 minute mid drive the battery warning light flickered on and off but has stayed off now, any ideas?

I rechecked the battery at the end of the drive and it was showing at 10.70 with the engine off, shouldn’t it be around 12?

sorry for all the questions, still find electrics the dark arts! Plan is to replace the stereo and check the radio loom for a bad earth bit still not 100% that I’ve resolved whole issue, but sure I’ve found the source of drain, thanks to your help, cheers
 

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Full of Cr*p....
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It indicates that the stereo has been wired as a "permanent live", rather than a switched supply.
Red/yellow wire swap on the loom should cure that.

As for the battery, if it's been allowed to go "flat", it will need a proper charge from a mains charger.
Driving even for 24 hours will not charge it properly.
Could also be a duff cell in the battery....not unheard of even in a new one if it's been over-discharged.

Warning light "could" mean the alternator is in need of a new regulator/brush pack....about 30 quid, and can be changed without removing the alternator.
A couple of threads on it if you search the forum.
 

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Premium Member
Joined
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176 Posts
Discussion Starter #5
It indicates that the stereo has been wired as a "permanent live", rather than a switched supply.
Red/yellow wire swap on the loom should cure that.

As for the battery, if it's been allowed to go "flat", it will need a proper charge from a mains charger.
Driving even for 24 hours will not charge it properly.
Could also be a duff cell in the battery....not unheard of even in a new one if it's been over-discharged.

Warning light "could" mean the alternator is in need of a new regulator/brush pack....about 30 quid, and can be changed without removing the alternator.
A couple of threads on it if you search the forum.
Thank you so much for all the help, I’ll charge the battery and sort out the alternator too, cheers man, you’re a star
 

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Full of Cr*p....
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8,877 Posts
Wait until the battery is fully charged before worrying about the alternator....
It "may" have just been that the voltage was so low.

If it shows 14.2 - 14.4 volts when emgine is running (rev to 2000rpm to check), it's probably OK.

Electrics are probably the only thing I'm 99% sure of..... :whistle:
 
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