Battery Drainage

[E30Adam]

My car has developed a severe battery drainage problem, if you leave it overnight, it struggles to start the next day. If you don't drive it for a day, it's completely dead when you come back to it.

Are there any common problems that cause battery drain on the E30, what sort of tests can I do to try and find out what's actually causing the problem... I have a multimeter!!

I have an alarm installed, don't know if that has anything much to do with it??

[Simon]

I would say the alarm, theyre always causing problems, how old is the battery??

[Lordschleife]

Yeah, could be battery age I've had that
Also if you've messed with the stereo recently? I've seen them drain batteries before!

[E30Adam]

The battery is only about 6 months old at most and it's a beefier one than the stock item so should carry plenty of juice.

It's a Clifford Alarm so it wouldn't surprise me if that was the problem

Any ideas how I can test?

[andyp]

try the boot light,aerial, what is the multi meter saying

[Lizzie]

I've been experiencing major battery drainage. It was getting that everytime that I needed to start my car, I had to use a booster charge. My battery was dead. After thinking about it a while, Demlotcrew and my papa have come down to the conclusion that it is my electric aerial.

I've had the aerial detached and the car seems to be okay now. Although, I've just had fitted a Solar Car battery charger today.

This should help stop any minor battery leakage too.

Incidentally my battery is a Bosch Silver battery that I bought in August last year.

I, like yourself, thought it might be my alarm, but I didn't put it on for a couple of days and it still kept draining the battery.

[nickp]

Adam,
Connect a multimeter in current on your + lead at the battery, see what sort of current she's drawing with everything switched off.
Then it's a case of pulling fuses and disconnecting bits one by one to eliminate various bits.
Obviously dont try to start her up with the Meter in series or it will be meter meltdown time.
Cant think of any other way to check really .
Good luck mate,
Nick.

[BMW325AW]

im not exactly sure if this is availible where youre at but have you ever heard of the battery tender??? I use it on my quad(4x4 dirtbike) and am going to use it on my e30 in the future. I connects to your battery almost permanantly and plugs into the regular wall outlet in your house. It constantly monitors your battery and charges it when it drains. I have never had a problem with it and i always start up perfectly. Ive left my quad sitting for months on end and it always starts right up. My friend uses it on his old e30 as well and it always starts up too.

http://www.batterytender.com/

check that site out and see if you can get it delivered to you! I hope this helps m8!

[M3RAGS]

Adam,

After sorting battery problems on various cars including my mk1 golf and m3 I reckon I can help you diagnose it.

Do a few things for me.

Get a multimeter out and measure the voltage across the battery terminals, should be about 12 and a bit.

Now start the car(if you can !) and then get your multimeter out and the voltage should be 14ish. Now if its anything less than 13.3ish I would say your alternator has had it.

If the output is strong then your next job is to turn on all your ancillary things one at a time and keep an eye on the voltage. Lighst , stereo etc. See how the alternator copes. My m3 had a silly problem of the alternator just being crap under load.

A buggered alternator can cause the battery to just drain itself by leaving an open circuit.
If none of the faults above are happening then it could be anything from alarm drain to a boot light etc staying on!
time to pull fuses and see current drains.I think total bmw have a good test for this.

So Adam,it could be time to jump in the boot and get your best mate to shut it on ya! or just stick a video camera in there if you have no mates.

Try that and get back to me, I have a few other options.

With regards to the battery optimiser,its a good thing to have but if you use the car regularly it is kind of masking the problem you already have. I assume you use your car regularly, like.

Get meon msn, i have tried you a few times but you never seem to be there(or I smell or something! )

Rags

[jmc330i]

Adam.

I had the same problem on mine for about 3 weeks. Turned out that the boot latch had come loose and was leaving the boot light on all the time.

My alarm kept going off (cause the light was on) but I thought it was playing up so I turned it off. I realised what was going on when the boot opened itself whilst braking for a set a traffic lights.
I replaced the latch so the boot shut properly and both alarm and battery problems were sorted.

Might be worth a check before spending any money on it.

[M3RAGS]

any luck adam?

be good to give us feedback so it can be of use to other members if they have a problem?!

Cheers

[MarkP]

Im glad i seen this thread, its got me thinking!
When i recently bought my sport the battery was knackered so i replaced it with a brand new one thinking it was because it was just old and the previous owner had a bit of a sound system in it.
Maybe there is a problem that I never noticed and it might raise its ugly head again soon!
Gonna get the multimeter out tomorrow and check!

[motorsport]

Got the same problem, the battery will charge when driven but when it's not used it will flatten totally in around 3 days. I've already checked the bootlight and it was sticking, however this is fixed but it still flattens. I'll try the aerial and then start pulling fuses. Apparantly the driver's door lock heater, activated by lifting the drivers door handle, can corrode and stick on permanently.
I think a single answer may sort out a few peoples problems here.
Andy.

[Quaser]

Faulty Starter motors, and alternators can cause the problem too.

So, so far we have:

Boot light
Alarm
Electric Ariel
Alternator
Starter Motor
Door lock heater

What i would do is connect the multimeter and measure the amps.

With the car off (& ignition out) the draw should be about 0.3 amps.

then start with disconnecting the easier stuff (alternator, starter etc) until the battery drain stops!

Q

[motorsport]

Right folks, i fitted a new battery and placed an Amp reading device on the neg feed with the ignition off and it read 3 amps was being pulled/leaked from the battery.
I then started pulling fuses and checking for a drop, however every fuse was checked and the 3 amps was still being leaked.
i can only assume it is something directly wired up that is not using a standard fuse box. maybe stereo/amp etc.
Any suggestions, i thought of the alarm but it was switched off with the key before the check.
Could the starter motor/alternator still be at fault, although the alternator is only 12 mths old and the starter motor has never faultered.
Cheers,
Andy

[andyp]

[quote="
Could the starter motor/alternator still be at fault, although the alternator is only 12 mths old and the starter motor has never faultered.
Cheers,
Andy[/quote]

i dont think it could be the starter or alternator if the car is switched off and just sitting there. mine does it after 7 or 8 days if not used

[Quaser]

It could be the alternator or started - just disconnect then in turn and see that happens

there are diodes (or something - cant remember what!) in them that can burn out and the alternator/starter starts sapping power instead!

Q

[MarkP]

On Jan 15th (in this topic up around the top) I said that I just bought my sport and fitted a new battery, on reading the topic it put a few seeds of doubt in my head that maybe there was a problem i wasnt aware of. I failed to check my battery like i said i was going to and voila! my new battery drained flat!
So im watching this topic like a hawk in the hope that someone can help me solve my problem.

Once I recharge my battery it sits at 12.8v when the car isnt running and when running it sits around 13.5v. I pulled out fuse by fuse and still the battery slowly drains, its a very slow countdown of about 10seconds to drop from 12.84v to 12.83v.
I left my car in yesterday to get the alternator checked and all is fine so that rules that out, the mechanic said that the alternator will only cause a huge drain.
I have now disconnected my headunit to see if its that, my electric aerial is powered from my headunit so this will test both.My next item that i will check is my indiglo dials in case the previous owner didnt wire them in correctly.
Now for my questions:
I have a TOAD alarm and am not sure how to test that its not draining the battery. People have posted that they have left their alarm unactivated for a few days to test it but surely if an alarm is wired directly with no fuse available it will always be in circuit, armed or not,am I right?
How would your starter motor drain your battery?

[Richy325iTouring]

there should be an inline fuse somewhere for the alarm so take that out and then check to see if the bat stil drains

[MarkP]

I had a look in behind the dash today and found 2 fuses for the alarm, a 15amp and a 5amp, removed both and the battery continued to drain very slowly,even when running!

Someone mentioned that driver door lock heater which i wasnt aware existed,is that a real possibility?

[motorsport]

The driver's heated door lock is wire via the fusebox so pulling fuses would show up a flaw in this.
Carry on! I'm at the same stage too.
Andy

[bren]

Afternon all, I am having the same problem with my battery, car not driven for 3 days and the battery went dead, I had the altanator replaced two weeks ago, so thats not the problem. If you guys find your problem can you keep the rest of us informed, electronics not my strong point.

Ta

[MarkP]

Anyone any updates on their search to cure their battery drainage?

I havent solved mine yet but i was looking at my 2 interior lights and noticed that when a door is opened and the light is not set to light up there is still power being used from the battery,just a little bit of info.

[Brianmoooore]

Battery drain on an E30 should be about 30 - 50 mA, not 300mA.
If you've established that there is a fault, by connecting a meter in the battery neg lead, and pulling fuses doen't clear it, then the next step is to take of the battery pos lead (or the phantom battery terminal on the bulkhead, if you have battery in the boot), and remove the two smaller leads from it. Reconnect these one at a time with the meter in series and see which one the drain is dissapearing down.
If it's the big one, then it's probably the altenator.
Care required, as these wires make big sparks if you touch the bodywork with them.

[MarkP]

Can anyone tell me what voltage a car battery should be sitting around when fully charged?

Where are the earth wires in the engine bay? I think these can cause drainage so i want to replace them.

[eric]

I had a similar fault on my 318iLUX, whilst driving the lights would dim, the stereo would die and the wipers would go slow, and if left for more than 5mins would sometimes be flat enough not to start the car.

It turned out that the new alternator that I had got from a motor factors and fitted was at fault along with the main battery/starter/alternator cable.

New cable and alternator fitted and all is fine (apart from the tickover problem and cutting out when the clutch is depressed!?!)

There is normaly 2 earth leads, 1 from the either the starter or alternator to the body and 1 from the engine block (mine was from the drivers side engine mount bolt) to the body. Try cleaning them with emery cloth 1st before you replace them as a dirty connection can cause problems.

[Danstable]

Let me add my name to the list of E30 owners experiencing this problem. Isn't it odd how we all seem to be experiencing similar problems at a similar time......could this one be down to the cold weather do you think?......i.e. heated locks, mirrors, washer jets?

Dan

[Guest]

me too i spoke to Lizzie about this and i have invested in a solar charger she says hers works a treat so i am giving it a go pluged it in tonight should start working first light tomorrow with any luck ???

Lars

[E30Adam]

any luck adam?

be good to give us feedback so it can be of use to other members if they have a problem?!

Cheers

Hey Rags,

Only just checked back to this thread, the car failed it's MOT so hasn't been used for the past month or so. I'll certainly try your suggestions when it's back up and running to try and diagnose the problem.

[Danstable]

Just done a test or two on my 325 and I think the brushes/voltage regulator is the culprit.

My freshly charged battery shows voltage accross the terminals of about 12.4v

With all anciliaries off, and with the engine running at about 1500 rpm, the voltage accross the terminals starts at about 14.3v then slowly climbs. I disconected everything when it got to 15.25v as the Bentley Manual says anything above 14.2v indicates a faulty voltage regulator.

I also tried to do the fuse pulling test but couldn't get the meter to read anything other than -1 with the engine off and ignition out. I understand it should show 0.3 amps or so? Didn't start pulling fuses as I assumed that I mustn't be using the multimeter correctly.

To do that last test I disconnected the negative from the battery, held the black meter cable to the negative cable, and the red one to the negative terminal of the battery. The multimeter was switched to 20m if that means anything to anyone, I did try it in other positions but got nothing but a zero or the minus one.

Does anyone that understands what I have said, think that I am right to order new brushes and voltage regulator? Although I think I only need the voltage regulator, the two components come as one part I believe.

Dan

[Brianmoooore]

From what I think you're saying, you're right to try a new regulator / brush pack.
When using most multimeters to measure current, you have to move the red lead to a different socket on the meter from that used for most other measurements. Could this be an explanation for your odd meter readings.
0-3A (300mA) is very high for a static battery drain figure. Depending on what clock / radio / alarm you have fitted, I would expect a figure more like 30 - 100mA.
When using the meter to check battery current, always connect the meter in the battery negative lead, and beware of the central locking operating when you reconnect the battery through the meter, which will possibly fuse / destroy your meter.
Best way to do this, is to loosen the battery neg. terminal, clip the meter black lead to the car body, then press the sharp probe of the red lead vertically down into the middle of the negative terminal. Then twist and lift the battery terminal up off the battery post, around the meter probe. This avoids disconnecting the battery at any time, and any of the problems that arise from doing this.

[MarkP]

Had a small bit of progress with my drainage problem.
I set my multimeter to read what drainage my car was taking from the battery (0.48v) and then removed wire by wire from the power point in the engine bay. Eventually I discovered that the drainage is coming from 1 of these wires.
The power point i am talking about is the place in the engine bay that the battery would sit if it wasnt in the boot.
Now, does anyone know what each wire that comes off that block is for?
The wire that i need to know about is the one that, when facing the car with the driverside on your left, its on the top side of the block and closest to you. It runs along the back of the engine bay then down to god knows where!

[Brianmoooore]

How many wires in total come off this point on your car, and what size is the relavant wire compared to the others?

[MarkP]

At this point there is 1 very thick wire that is connected into the block at the back,this is about the thickness of your finger. Then there is a thinner wire beside it,in at the back, and it is bolted on. Below that is another wire. Next to it but on the upper side of the block,nearest the headlights side of the car is the wire that i have my drain on, it is the same thickness as the other 2 wires( about normal 3 core size).

So in total i have three wires bolted onto the block and then the 1 thick wire that seems to come out from the block itself.

[MarkP]

Here is a pic of the block since my description above is pitiful.
The wire with the black arrow pointing towards it is the one that is sucking my battery dry.