Flat battery again.... cant find why

[liam012]

Are there any tests to see if electricity is working ok - have a flat battery again - happens quite alot.
car reads 13.5 volts when running so must be a drain or something?
quirky thing is that when the car is totally off and no keys in the ignition the electric windows will work when you open the doors but wont work if you close the doors - work as normal when car is running.
this started happening a little after when i changed my starter for a prefacelift one
see this thread:
http://www.e30zone.co.uk/modules.php?na ... ter+friend
any ideas?
cheers

[Chris]

Hey mate, i'm not to sure about the tests to find out if its all working ok but if you run a multimeter between the negative batt terminal and a known good earth while everything is conected up and the ignition is off it will tell you if it is the car useing power and not just a knackered battery.

In E30's with the ignition off and the door open it is normal to be able to operate the windows and roof, (only mine doesnt he he)

Sorry i cant help more with it all,
I'm sure Brianmooore will be along soon to fix it for you, i swear he knows everything to do with these cars lol

Cheers
Chris

[liam012]

what should the reading be between the negative terminal and good earth - i would presume zero volts?
thanks

[DaveD]

its usually the light in the boot....try putting a multimeter across each fuse that would at least isolate the drain

[liam012]

will try that with the fuses
kicking myelf for not thinking of it!!

[fowler]

ther is an earth on the starter which brings in relay K7 check this as i had the same problem, could be relay K 7 which is permantly stuck onbut doubt it my first suggestion is the way to go
cheers
ben

[liam012]

update
got a jump start before i left work to come home- when running the terminals actually read 12.5 not 13.5 and that was using several different earths as well as the positive terminal all read the same or a little under. (i thopught it was reading 13.5 because it was one of the times i got a jump start recently - it seems to haave got worse.)
seems to be know drain to earth when standing unstarted but with the battery so dead who knows,
with the battery removed from the car after a 1/2 hour run home it reads 12.08 volts and still wont crank too dead.
plugged it into battery charger and is reading barely over 3 amps.

tha k7 sounds interesting as i have have not got the same starter as original as termials are marginaly different on the pre facelift.

will get the battery fully charged and then test again for everything - fuses/relays and alternator running voltage. will report back findings!

thanks for all your quick replies[/b]

[fowler]

mine was a pre facelift engine out of an 87 motor
has two prongs on the starter
one is both are eaths and the earth betwen statrter housing and block breaks down and is shit
alos check earth nto body and any other earths as
it sounds like you could have a drain off the alterantor. disconect the +ve terminal on you battery and connect a multimeter in line with the battery and the diconnected wire Red lead on battery and black lead connected to the diconected wire and see if there is a drain most likely altenator or stater if it is not this i would investigate the earths on the starter motor

[Brianmoooore]

Whatever was wrong with your windows, you repaired it when you changed the starter motor. What they are doing now is what they are supposed to do!
DON'T TOUCH THE POSITIVE terminal of the battery! Very dangerous. Lots of amps available!
Connect a meter, set to measure current, not volts, between the battery negative pole and the earthing stud on the RH front suspension turret. Then remove the battery negative clamp from the battery without removing the meter probe. Normal current flowing then should be 30 - 50 mA. Anything much more needs investigarting by pulling fuses and disconnecting the smaller wires from the battery positive, with the negative lead and meter disconnected while you do it.
Fully open a window before you do any of this, as long forgotten alarms can be activated by messing with the battery, and they may just decide to lock you out of your car!

[Globulator]

Sounds like it is not charging.
Should be 14.4V odd when running
13.8v after you switch off.

Remove the boot light to eliminate that while you pin it down.
Flattening the battery could also have killed it - sometimes it does.

Try a new/good battery and measure while running to see if the charging stuff is OK.

[agent006]

Try a new/good battery and measure while running to see if the charging stuff is OK.

Had a similar problem on my Audi, turned out the battery was trousered. Would discharge over a couple of days use, bought a new one and all was well.

[fowler]

cheers for that brian for got to mention all that long hot day at work should be something really simple
as for the windows do you mean when car is running they do not work when the th door is shut ???
still sounds like it could be a drain from a small circuit !
What about the trusty Glove Box torch light charging circuit ??
i would presume if it goes that flat it has to be a large drain !
as it seems also not enough amps to crank the car.
HOw old is the battery ? silly question but need all the info as i have the drawings in front of me today

[Brianmoooore]

ther is an earth on the starter which brings in relay K7 check this as i had the same problem, could be relay K 7 which is permantly stuck on

K7 stuck on wouldn't normally give a significant battery drain unless you have heated mirrors. Clue would be that the mirrors and heater fan work with the ignition off.
The other unloader relay, K5 could also jam on, but the window switches would be lit (and the windows work) with the car parked up.

[fowler]

brian i had the same problem with the windows and heater as you said the unloader relays i found that the earth from the fuse box to the stater was fucked when it puts the +12v feed down the earth when starting the car
Is the rear demister window another favourite for drains???
Also The breakdown in the contacts in the head light switch can cause it i think ??
sorry rambling now oops !

[Brianmoooore]

What about the trusty Glove Box torch light charging circuit ??
i would presume if it goes that flat it has to be a large drain !

Interesting suggestion that I don't think I've ever seen before, but there is a fairly high value current limiting resistor inside the torch, so, even if the battery has gone short circuit, which they frequently do, the drain won't be significant.

[fowler]

JUst Had a thought dodgy ignition barrel ?????

[Brianmoooore]

Rear window switch is only live in ignition positions 1 and 2, so shouldn't be responsible for current drain problems.
The way to solve this is quite simple:
Start with a charged battery, test for current drain with engine stopped and ignition off.
If excess drain is present, find out what.
If no excess drain, start engine and measure battery voltage.
If 12V - 13V, suspect altenator.
!f 14V, suspect battery.

[samr]

I had the same problem on my 318i 2dr, turned out for some reason that the electric windows were draining the battery, because the isolating switch was off [the window switches light up], as soon as I isolated them, battery was fine.

[Brianmoooore]

I had the same problem on my 318i 2dr, turned out for some reason that the electric windows were draining the battery, because the isolating switch was off [the window switches light up], as soon as I isolated them, battery was fine.

You hane one weird bit of wiring!

[liam012]

thanks lads
turned out to be loose connection from alternator to starter.......oops
car seems to start just as eager every time over the last few days so battery is not getting progressively weaker like before
only reads 13,4 at 1500rpm though so i think ill recon my spare alternator and throw it in to be safe.