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Keeper of E34
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Discussion Starter #1
Yes, after a possible cracked crankshaft and wonky cooling system (see previous posts), I have realised that the battery that was in it was not old and gave up the ghost, it was my car. I put a perfectly functional battery into it and within a couple of days there isn't even enough charge to turn over the motor!
What the heck is going on!
Really - I have read about this kind of thing before, but I am stumped. At this stage I am surprised I actually drove it all the way home...mind you , that burning smell made me a but suspicious, but I was told that is the smell the catalytic converter makes.... Any ideas?
 

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maybe the alternator? you can get it checked to see is it working without having to take it out at some garages :D
 

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Easy check on your alternator, is to aim your lights at a wall and rev the car, if they go brighter and then dim slightly as the revs die down, the alternator is at least working.
You could also have a drain on your battery, as in something staying on when car is turned off. This is a harder one to get, I had an issue before and I got a current sensor that had a connector on it that fitted into a blade fuse socket - so I could get a reading of what each circuit was drawing. Also you could get a current clamp and put it around the main battery cable and remove each fuse one at a time to see if the draw is significantly reduced.
 

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Keeper of E34
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Discussion Starter #5
Thanks for the guidance. The battery is definitely charging - very well too - I have a battery and alternator tester. So it must be something in the car draining thebattery when the mtor is off, stage 2. checking the current drain. Someone fit a cut off switch to the fuel pump - could this be the cause?
It is a 1991 518, a bit the worse for wear. No air con.
 

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Gunner
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A light staying on overnight will drain the battery, or if you have a radio on standby all night.had same probe turned out to be my amp which powers subs was staying on. most common culprit boot light.
 

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Also you could get a current clamp and put it around the main battery cable and remove each fuse one at a time to see if the draw is significantly reduced.
clamp on meter will only work with ac,
one lead will need to bo taken off the battery and the circuit completed with the leads of a meter set to amps dc, current is now goin through the meter,
total current shold be low when the car is off, im guessin lower than 1 amp, as average 80 ampere hour battery would only last 80 hours at that current draw,

so start pullin fuses and see what reduces it alot
 

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Keeper of E34
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Discussion Starter #8
Connect the what to the what now?

Thanks for the advice - so just to go over that once more before I try it myself. Connect one lead to the ... terminal of the battery, and the other to the ... (Don't worry I amn't going to ask anyone to draw a picture/diagram, or better yet, take photos). :)
 

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disconnect battery. Then put one probe on battery terminal, and the other on the lead. Dont short lead or never probe to body of the car, that will end in fuse blown inside meter, oh and have meter on highest setting A dc dont set it to mA dc, but you might have a meter that will autorange

your basically breakin the circit when you disconnest the lead, and remaking it with the meter, so the current flows through the meter giving you a reading, oh and you will need to have the red lead in the right hole on the meter
 

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clamp on meter will only work with ac,
one lead will need to bo taken off the battery and the circuit completed with the leads of a meter set to amps dc, current is now goin through the meter,
total current shold be low when the car is off, im guessin lower than 1 amp, as average 80 ampere hour battery would only last 80 hours at that current draw,

so start pullin fuses and see what reduces it alot
A decent clamp meter will work with ac or dc .
Has the car got a after market radio fitted , if so start there
 

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A decent clamp meter will work with ac or dc .
Has the car got a after market radio fitted , if so start there
well yea of course, but with the dc he will have to break the circuit and complete it with the meter, not just clamp it around the cable as in ac is what i really meant:eek:
 

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clamp on meter will only work with ac,

One I used gave useable results :confused: - pointed to the car stereo and door lock heater. We use one on high power DC ccts, so just assumed that it would work on the car battery as well - It is a pretty good one though.

Very easy to blow the fuse on the current meter by putting it in line with the car batt, touching, shorting, over current from switching etc... As the others have said, start pulling fuses !!
 

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Keeper of E34
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Discussion Starter #15
Fuse 28

OK - used my little multimeter, connected it in line to the battery. Showed an initial current of c. 0.8 A then climbing rapidly up to c. 4.8 A. It remained steady until I pulled fuse 28 - seems to be used for lots of things, including the rear window heater, but when I put it back in it remained at c. 0.7 A when all other fuses - including 28 were pulled. What could this be - a faulty switch?
I will see if I can repeat this, but if there is a drain of almost 5A on the battery with everything switched off I can see why it might run down over a couple of days. Any comments? I don't have a meter that will clamp on, what is that called?
There was also a fuse in a blank slot. Why.:confused:
 

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Gunner
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Fuse in blank spot= Spare fuse:D
Had a few u in my fuse box too bt i think they're all blown now loL (Except the necessary once offcourse)
 
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