Battery draining

[charlie316]

I have a problem, my batterey keeps draining over night, i thought it was an amplifier i had fitted but i have taken this out now so everything is standard. Does anybody have an idea what it might be or any way of finding out? Its starting to get very annoying bumping the car off everytime i want to go to the shops.!!

[e30cossie]

is it a new batterey .iv just brought a new one because mine is old and wont hold the charge.

[charlie316]

No its an old battery but it only started the other day, i might try charging it then testing it to see if it holds its charge.

[Brianmoooore]

Modern batteries tend to fail very quickly. One day perfect, the next day a little sluggish, the third day dead.
To establish if you have excess drain, you will have to measure it with a meter.
First, wind down the driver's window, then open the bonnet and loosen the negative terminal on the battery.
Set your meter to a range of a few hundred milliamps, clip the negative lead to the earth terminal on the top of the RH suspension turret, and push the pointed end of the positive lead vertically down into the centre of the negative battery terminal.
Now, lift the battery clamp off the terminal without removing the meter probe, and the meter should give a reading.
Adjust the meter range to give a "sensible" reading on the meter. 30mA is typical; 90mA is about maximum.
Anything more requires investigation.
Replace the battery clamp on the battery terminal, and remove the meter probe.

[topspark]

As brian says but i would start pulling fuses with the meter connected until you loose the current drain, I found i had a dicky electric aerial on mine using this method. If you think it may be your battery , get it drop tested at a garage , although they anit expensive now . I got a bosch silver battery from costco last year for Ԛ£35.

lee

[SPADGE]

Another very simple way of testing if its the battery or a drain fault would be to disconect the battery earth overnight and then put it back on in the morning and see if its still discharged. If it is its the battery. Obviously if you leave it out at night and are reliant on the alarm then this may not be a good idea lol!

[dobbie82]

I had it when my fiat boot light stayed on, only way to test in an e30 is to get a mate to lay in the boot while you shut them in!

[Falkster]

I had it when my fiat boot light stayed on, only way to test in an e30 is to get a mate to lay in the boot while you shut them in!

Exactly the same issue that I had.....took me ages to find out what it was

[charlie316]

Cheers for the advice zoners, i took the battery out over night and kept testing it with a volt meter and it has not dropped so im guessing its something else, after looking at the haynes it seems to back up what you have all said so i guess i will be going wild with the tester later! oh the joy.

[charlie316]

Right, after testing the alternater it is not that, testing all the fuses whilst connecting a volt meter it stopped when i took out fuse 21 which i believe is the door connections and the interior lights, so i disconnected all the interior lights and left the fuse out so i obviously hd no interior lights, this stopped the battery draining on the voltmeter but low and behold after a drive to charge the battery up i come back to it that evening and its dead. The only thing i can imagine it being is the battery! any ideas before i go mad? .

Also where can i find a cheap battery?

[Brianmoooore]

Have you measured the voltage across the battery with the engine running?

[bill_620turbo]

Have you measured the voltage across the battery with the engine running?

I was there when Charlie was testing the battery, it was producing a stable 14v with the engine running.

[Brianmoooore]

Get the battery fully charged and take it to somewhere that sells batteries. They will test it under load for you for free, in the expectation that you willbuy a new one off them if its faulty.
Most of the static drain on an E30 (30mA-90mA) is through fuse 21 normaly.