E30 Zone

The car's been stood for around two weeks. I expected the battery to have drained a little but came to it and there was zero charge whatsoever...odd?

Jumped the car and drove it for around an hour and a half. Three hours later the charged had gone completely once more!

I don't know where to start to diagnose the problem. It's never done this before in the year or so I've had it...I have recently had some issues with my wiper motor (which are as yet unresolved) whereby the wiper was sticking in the down position after wiping just once. Might the motor be draining the battery by continually trying to move the wipers?

Any help would be appreciated,

James

I had this for a while and was trying to find a current drain, it would be fine one minute and then go totally dead out of the blue... but all I needed was a new battery!...the wipers have no power with the ignition off so this is not likely the cause no?

I sincerely hope it is just a new battery required! Beauty of a two-year BMW parts warranty

Factory alarm ?

or ensure your boot light and glove box light are going out with the door closed.

the only real way to find a current drain is to fit a multimeter set to read current in DC amps in series with the battery negative.

then see the standard current drain with ign off. a few mA is normal. anything higher then begin pulling fuses one by one. once the reading drops you have found at leats one source of the drain, then its a case of identifying what componant the fuse protects and then rem oving componants. note you may have to remove more than one fuse for certain items

mrLEE30 wrote:or ensure your boot light and glove box light are going out with the door closed.

the only real way to find a current drain is to fit a multimeter set to read current in DC amps in series with the battery negative.

then see the standard current drain with ign off. a few mA is normal. anything higher then begin pulling fuses one by one. once the reading drops you have found at leats one source of the drain, then its a case of identifying what componant the fuse protects and then rem oving componants. note you may have to remove more than one fuse for certain items

This is spot on, But disconect the batt completly first and check the amps are correct for the batt and that it is still ok before doing this. (i would fully charge the batt first)

you cannot check a battery with just a multimeter as there is no load on it, you need a resistive load that short circuits the battery and draws a decent amount of current from it, then judging by the amount of current flowing the condition of the battery can be accertained - this is what a battery checker does.

All you can do with a multimeter is measure voltage accross the terminals - which should be around 12.5-13 V

Thanks for that guys! I'll get on it today and see where I end up...

Martinaston - no, I've got an aftermarket Cobra affair.

The word multimeter imply's that the meter does multible task's Ie. checking volt's, Amp's , Ohm's, Resitants.there for it can be used for checking the condition of a batt.

So a batt rated at 500 amp's at full charge Should red 400 amp's + if it is in good condition when disconected. When it has a load on it then you can determin weather it has a power drain that is to high or not.

I have the same issue and called on the ever helpful mr mooore...
http://www.e30zone.net/modules.php?name ... highlight=

Two-year BMW parts warranty to the rescue! Dud battery is the problem, pleased to have it resolved

zaust wrote:The word multimeter imply's that the meter does multible task's Ie. checking volt's, Amp's , Ohm's, Resitants.there for it can be used for checking the condition of a batt.

So a batt rated at 500 amp's at full charge Should red 400 amp's + if it is in good condition when disconected. When it has a load on it then you can determin weather it has a power drain that is to high or not.

?? Are you suggesting connecting the meter across the battery on an amps range?? I really wouldn't advise doing this!
The only way you can apply some load to the battery while you test its voltage is to turn the ignition, headlamps, foglamps, reverse lights, heater fan and wipers all on.

Two-year BMW parts warranty to the rescue! Dud battery is the problem, pleased to have it resolved

Good stuff.........is this the first time I have been right about anything??

Glad you got your problem sorted
Even if your battery was just flat (as opposed to defective), driving round for half an hour will not have given it a meaningful charge anyway.

If anyone wants to diagnose a battery properly, you could do worse than using something like these two little beauties:
http://www.pvrdirect.co.uk/productinfo. ... BT91%2f7PF
http://www.pvrdirect.co.uk/productinfo. ... tRef=AK414

The first performs a similar test to the one detailed by Brian above (i.e. it applies a load to the battery and measures the voltage simultaneously).
The second uses the specific gravity of the electrolyte to determine the state of charge. Also, this device can tell you if the battery has a duff cell, and you can see if the electrolyte is discoloured. For something so cheap it's amazingly informative. Can't be used on sealed-for-life batteries, of course.

Pete.