E30 Zone

misterious battery drain every 5-7 days in a way that it doesnt even crank the engine. checked anything i can check, no short in the sound system, also, the trunk lid light switches off (asked someone to close the trunk while i was in it ) .

i don't think it's a short, i think its a consumer that slowly drains out the energy.

also i checked with a voltmeter +lead from the fuses, - to a bolt in the car, with the battery connected. the fuses from numbers 21 to 28 show a 12V voltage. is this normal?
thanks!

somebody posted a thread about how to diagnose this quite recently. try a search for flat battery.

i found a few posts on draining batteries but no one resembled mine case. my stereo is wired corectly, i'm very sure. mem wire to live and the power to ignition.

i have no ideea what might it bee. might this have something to do with dead sii board batteries? pls help

You defo sure about your stereo being wired correctly? I had one once that if you didnt turn it off properly when you removed the face it was still on poxy thing took me 3 weeks to figure it out.

Also do you have a seperate power amp? Could just be a shagged battery...

the radio is def wired corectly and i always turn it off, but nomather, if i take out the key from the contact the stereo turns off, it can only be turned on when the key back in because the power to the stereo is from the accesories position, so no way it remains on after i take out the key.

and the battery is pretty new and in good condition. if i disconnect the battery and leave it for a month the battery remains strongly charged, it cranks the engine beautifully, but if i leave the battery conected and don't start the car for max 5-7 days the battery goes so low that it can't even turn the shaft once.

Get a multimeter out and find out what sort of current the car is drawing. Process is described in a few post. I use the "battery drain" and selected search for all terms and got a few good posts on how to actually diagnose the problem.

just use a multi meter, pull fuses one at a time, and you will see the problem when the amprage draw goes away.

Kyle

thanks, i found enough posts to get started on the job, wish me luck! i bet all my money on the si board batteries going dead or some screwy interior light that's hiding somewhere.

It's not the SI board batteries - they cause many varied problems, but this isn't one of them.
Stick the mA meter in the battery earth lead, and see where the current's going.
Faulty alarm or altenator diodes are the favourite, if you're sure about the boot light.

thanks brian, will keep in mind, i don't have the alarm though.
i'll take out the fuses one by one see in what circuit is the problem.

hey i was thinking, still, dead si batteries can't be a source for electrical drain?

let's say if you have dead si batteries and they are 800mA.
the charge system will try to charge them forever thus draining almost countinuous 800mA.

isn't that a possibility?

my car did this a couple of times turned out to be the glove box light problem is i cant get my wife in there to see if its gone out
so i had to use trial and error

well when i first checked with an ammeter the battery was draining 1.25 Amps with everything off. narrowed it down to fuse no 22. - parklight left
. that removed, after that it was still draining 0.19 amp. removed no 21 fuse, it still draws 0.13 amp. now 0.13 amps is drawing with the fuses out. how can that be?

it seemed like the positive parlight lead was not insulated so i think it was drawing 1.25 amps trough that.

but i still have to sort out the 0.13 amps. where can they come from?
i don't have any alarm and everything seems to be fused.

as i understand the normal curent drawing for e30 is 0.04 amps.

Could it be an OBC or clock? They are always on.

SORRY I didn't read all the posts properly durrrrr - I'll just get me coat

michael24m wrote:hey i was thinking, still, dead si batteries can't be a source for electrical drain?

let's say if you have dead si batteries and they are 800mA.
the charge system will try to charge them forever thus draining almost countinuous 800mA.

isn't that a possibility?

Never measured the charging current for the SI batteries, but I would be surprised if it was more than 1mA max.
The 800mA of the battery is it's capacity in mA/hr., not its charging current. I.E. Fully charged, it can supply 800mA for one hour.

bigkev wrote:my car did this a couple of times turned out to be the glove box light problem is i cant get my wife in there to see if its gone out
so i had to use trial and error

Don't remove the bulb to check for this. The empty bulb holder tends to short circuit the supply!

michael24m wrote:
but i still have to sort out the 0.13 amps. where can they come from?
i don't have any alarm and everything seems to be fused.

12V+ permanent live to the engine loom and the altenator are not fused.
The altenator is connected to the battery + by the thick black cable, via the starter motor. Engine loom is the red bolted to the battery + terminal which is not the feed to the fusebox.

oh god! guys, i found the stupid 0.13 amps drain. it was nothing on the fusebox.
check this out: it was a relay with 3 ground conections, the positive lead going from the alternator, and another lead that went to a switch in the dashboard, and the other lead from the switch down to the brake pedal sensor(the one that detects if the brake pedal it's pushed or not)

now i isolated the positive lead from the alterator, seems its been "a home made connection", and the problem was solved. turns out that relay was draining 0.13 amps constantly. i have no idea whatsoever about the role of the relay, the guy i bought the car from, said it was something that had to do with the abs, but it has nothing to do with that. it was basicaly a positive lead from the alternator and three earth conections, plus that crappy switch circuit that does nothing. weird stuff. solved, now the amperage looks like this: 0.05 amps, when i first make the connection to the battery and in 10 second it drops to 0.00 amps. so no drain.

Word of warning for anyone disconnecting and reconnecting the battery.
Make sure you have the keys on you, or open a window.
Some alarms will activate and lock the doors when you connect the battery.