My dad owns an R plate BMW 523.
Hes been having a few problems with the battery going flat when left for extended periods of time (=>3/4days). Its not due to driving short distances as he drives to carlisle and back from nottingham each week. He has had a brand new BMW battery and the problem still persists.
It seems to me like there is some kind of grounding happening somewhere when the ignition is off.
Anybody had similar experiences? Any suggestions?
ta,
Mark.
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Check across the terminals with a multimeter - there should be a small drain (clock etc), but if there is any short or grounding, it will show up.
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Oops, then pull fuses one by one, while checking the meter. This will allow you to pinpoint which circuit - if any - is shorting
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MM
Had exactly the same symptoms with my Disco and after several so called Garages told me the battery was duff, new one purchased. Finally sought the advice of an Auto Electrician who slapped a Multimeter? onto the battery and discovered an abnormal seepage/drain from battery when stood. Fault traced to spot lights that had been incorrectly wired. Rectified and now no more trouble. Took over 3 years, 2 garages and 2 batteries to sort out.
DVD
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Should not this mulitmeter be connected in between the battery and a removed battery cable to measure current drain?
Just across the battery will measure voltage but wont show any drain current.
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MM.
If you look back to my post re: Maestro alternater which was faulty, This knocked the battery flat overnight even though it was charging when running.
However the battery warning light stayed on even when the key was removed so this was a large discharge.
Alvin
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I recall a friend having a similar problem on another make of car. The dealer fitted a new battery, then a new alternator, but still no joy. He eventually found the cause -- the boot light didn't switch off when the lid was closed.
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Alwyn,
Wouldn't you have the multimeter set to amps and not volts which would then show the discharge amount.
Alvin
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No, the current has to be measured in series, i.e actually in the path of the current - through the meter.
If it is placed across the battery connections you will get a voltage reading.
In any electrical circuit you will find ammeters in series and voltmeters in parallel.
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Alwyn
You're absolutely right. The need is for an ammeter in series with a disconnected battery lead (preferably earth). A meter across the battery will tell you nothing.
Current drain should be in the order of 20/25 milliamps. If it's flattening the battery in a couple of days then it will be significantly more. Remove fuses to detect the faulty circuit.
regards
John
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There have been cases of battery drain being caused by engine management computers failing to disengage power relays after engine is turned off. To locate and rectify this is specialised work and can be expensive if an ECM is found to need replacing. Just a thought for you on your 523.
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Put ammeter in series with battery check amps being used,if excessive with meter still connected remove fuses one at a time and check for a drop in current , this should isolate the problem to a smaller area as fuses sometimes feed more than one component, be aware that disconnecting the battery may require a radio code being entered on reconnect, if you use a frig wire to the lead and battery you can overcome this problem connect the ammeter in parallel then remove the frig wire.
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I think its necessary to define 'excessive' in connection with battery drain problems.On modern cars up to 60milliamps is quite normal and does not cause the battery to go flat in 3-4 days. However any reading over 100 milliamps will cause trouble.
PS Could you explain what a 'frig wire' is
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A frig wire is a length of wire with usually a crocodile clip on each end useful for shorting out while fault finding(like a miniature jump lead), the clips just make it easier to attach
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Alvin - it's not the warning light that will flatten the battery, the faulty diodes in the alternator rectifier pack will allow battery power into the alternator and that will flatten the battery. The alternator will appear to be slightly warm aswell.
David
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David L.
No I wasn't suggesting that the warning lamp was draining my battery.
What I was trying to say was that I has such a big drain from somewhere that it was showing on the battery warning lamp.
I had picked up from my previous posts when you fella's kindly explained that it was the diodes in the alternator pack which was causing my problem.
In fact the auto electrician looked quite impressed when I aired this newly learnt diagnosis to him.
Or was he just think smart a***.?
regards
Alvin
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I had always used the rule of anything more than 20/25mA as excessive current drain, which is capable of flattening a battery over a few days.
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Not everyone has access to a meter. Had a similar problem on my car and found it by touching the disconnected battery lead to the post and watching for sparks. Make sure your doors are shut (courtesy light!) and that you have your radio code. Then remove fuses one by one to isolate. Mine was the glove box light!
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Ok Markymark, there you have it!
First off, climb into the boot, close it, and check the light inside! :)
Sorry I was "off" with my comments on metre connection - but I think you've got the idea by now.
Hopefully your dad's Beemer will get back on track soon.
Ian
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Yet again, you guys have come up with the goods.
Cheers Boys, I'll let u know how we get on.
Mark.
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