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General Information => Troubleshooting => Topic started by: molgrips on October 30, 2008, 05:10:14 am
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It seems to go flat over a few days. Fine, except that it's the second new battery I've had that did the same thing, and I've had the multimeter on the battery terminals and found that there's no current being drawn when everything's off. So wtf?
Could there be some kind of hidden drain I don't know about, that only comes in occasionally?
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have you checked the alternator.....its possible that it could be getting 14 volts but not charging amperage. or the diodes could be bad causing the light to come on and it not charging. or you've got a gremlin somwhere like your suggesting.
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Could there be some kind of hidden drain I don't know about, that only comes in occasionally?
possibly an exposed wire that is dangleing that grounds when it sways. i dunno
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If you have oem or an aftermarket alarm, you won't be able to check for battery drains by disconnecting the battery terminals because you are then disabling the system. If you do have an alarm or remote starter ,the only way will be to use a clamp on inductive ammeter to see if anything is pulling current while the battery is connected, doors locked and hood switch disconnected or enabled. If you can't do all that, then first try it with the radio disconnected for a day or 2, then any other accessories you may have. Before you test, also make sure ,while the engine is running, to engage all and any electricals, A/C radio etc, ABS etc, etc
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clamp on inductive ammeter
Ah yes, good idea... I did wonder if by disconnecting the supply briefly I reset whatevdr it was...
I still suspect the radio - it used to be always on, but I wired it into the supply for the heater fan so it works only when the heater fan can ie when ignition is on.
No alarm btw, but central locking.
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if you have CAA you can get your system checked... they have pretty good tools to do that. they test the battery, alternator charging system, and for any drains when the car is off. pretty sophisticated IMO, and saves a lot of guess work!
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hey mr tanguay, look where he is :wink: I think over there it's the RCFDECAA
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Just the plain old AA in fact :)
I'll get it tested as a last resort. This morning, after fully charging the battery overnight I put it back in the car and I saw a little spark as I reconnected the terminals. I swear, it's that damn radio, even though I wired it up to be off when the ignitions's off... grr..
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If you see a spark when reconnecting ,then that is a fairly large drain , at least 1 amp. the most you can have without draining a battery is 30 mA.
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I had a bad diode on an alt once. It would charge the battery, but would discharge through the alt when the car was off.
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I had a bad diode on an alt once. It would charge the battery, but would discharge through the alt when the car was off.
my golf had a bad diode for as long as i have owned it .....about 2 years. and i never had the battery drain on me. i dont think its the diodes
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I've seen both starters and alternators drain batteries, althought the starter one was weird.
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hey mr tanguay, look where he is :wink: I think over there it's the RCFDECAA
hmmmm didn't see that... but they must still have as good of technology over there in the UK :lol: :wink:
and diodes just control the flow of electrons... can a diode fail and allow bi-directional flow??? that can't be good
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Ok, so I went out to try another test just now and guess what - no sparks.
:?
I carefully took the battery conection off whilst keeping contact via the multimeter, and no current. Great. So it only happens when I least want it to..... :evil:
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What setting are you using on the multimeter?
Have you verified that the alternator is charing?
How big is your stereo? If it's drawing more power then the alternator can provide, the battery will go dead.
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Try isolating the starter.Mine is behaving the same,It turned to be the starter.I even took it apart ,cleaned and degunked everything,no change.Check for post insulation or lack there of.
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my golf had a bad diode for as long as i have owned it .....about 2 years. and i never had the battery drain on me. i dont think its the diodes
Diodes can fail open... in which case they generally cause no symptoms other than a decrease in the available output power of the alternator.
They can also fail closed... in which case they will usually drain the battery by causing a direct path for current thru a field winding.
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Every couple of hours of driving, roughly, the tach goes a bit crazy for 5 minutes and then returns to normal. It's the alternator, cos if it comes back in when I'm idling and the fan/lights are on I can hear the engine note dip.
Stereo is a basic small one, nothing fancy.
Something else I noticed today - the central locking keeps making that noise it makes for a few minutes after I lock the car, but I heard it again today a good three hours after driving it last. This could be the problem.
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Something else I noticed today - the central locking keeps making that noise it makes for a few minutes after I lock the car, but I heard it again today a good three hours after driving it last. This could be the problem.
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Very possible. I had a golf that, because the central locking had a leak, and didn't lock the trunk, the customer didn't know the truck wasn't locked, and lo- dead battery. The vacuum/pressure pump for the central lock has a function that shuts it after a 30 secs. if it's still running. however it sounds like yours isn't working as it should.
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I had a problem with my trunk light staying on it took about 1 day of charging the battery back up to full charge and the battery would die again, I removed the altanator from the system and I still had quite a large arc at the batt terminal :shock: so I got a thinkin, I replaced my trunk lid a week before and had no idea how the inside trunk light turns on and off , I still dont !!!, so I removed the light bulb from its holder and I haven't had a problem since :lol: :lol: :lol:
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Wow. I'm happy for you but what a head ache! You won't forget to check that ever again next time you're having batt troubles. Takes two seconds to check but, obviously, easily overlooked.
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Given the fact your tach goes mad the following is unlikely but just something else to consider if all else fails...
My dad had a problem with his mondeo battery occasionally discharging. I traced it to a leaking rear light which would fill the boot up with water only when the car was parked bonnet downhill whilst it was raining, which created the short which drained the battery.
My reason for mentioning it was you said you've tested and couldn't find a constant drain on the battery. However if you have electrical circuits which are getting wet occasionally the drain may not always be there.
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My dad had a problem with his mondeo battery occasionally discharging. I traced it to a leaking rear light which would fill the boot up with water only when the car was parked bonnet downhill whilst it was raining, which created the short which drained the battery.
That doesn't sound very unlikely to me! that's good advice. These lights do leak frequently when they age a little.
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Hmm.. interesting.. it does seem intermittent. I will keep an eye on when it happens next.