new battery dead

[twoscoops]

ok so I bought a brand new battery and put it in the car about 2 months ago. Everything has been fine since then until yesterday when I went out to find that the battery was dead as a dodo.

What is the likely cause of this? Should I be thinking about altenator??

cheers

[Rtaylor2208]

I take it you have ruled out the usual causes such as leaving the lights on etc etc.

Had it caused any issues before now?

[twoscoops]

yeah the lights were definitely not on and the radio headunit was off so I cant think of anything else that would be a drain on it mate. The previous owner had mentioned that he had killed the battery by leaving the lights on which is why I had bought the new battery to drive it away from him.

I had got the battery from farmers and I cheekily took it back to them and said it was dead. turns out it was Mr Farmer himself and he said he would change it and that I should bring the car down to allow them to check it which I will do. I just wanted to get a better idea myself encase it is something I can tackle.

[Rtaylor2208]

Have you tried recharging the battery to make sure it is indeed dead. If there was a fault in the car it would drian the battery but not neccessarily kill it completly.

If it wont hold a charge at all it should be covered under warrantly but you would have to prove that the battery is completly shot.

With a charged battery connected and the ignition completely off you can put a multimeter across the terminals and meausre the amps for drainage.

This should come back with a reading of about 0.1A, but hopefully someone can confirm this as I can never quite remember.

If substantially higher then something is drianing the battery. The usual subject is a alarm or imobiliser. Possibly even an amplifier if you have one that does not turn itself off when the stereo goes off.

Also a fully charged battery should come back with a voltage reading of something like 15V.

[twoscoops]

hmm right ok well the new battery is in the car now. The old battery was put on a meter when i took it farmers and it didnt even register at all, completely flat.

I do have an immobiliser on the car but dont have a volt meter to check any of this stuff with. If I can get my hands on one, how do i check the individual things like immobiliser, stereo etc?

cheers

[BenHar]

Look at the ninth post down here:

http://www.e30zone.net/modules.php?name ... c&t=213159

Ben

[twoscoops]

Thanks for that, I have ordered a multimeter from the bay. I will see what that shows and take it from there. I havent actually put the new battery in yet as I dont want to nail it until I can find the problem.

[bmw9818]

you can get a voltage pack off ebay germany, dont need a new alternator, just take the two screws out and manouvere the pack out, you might want to remove the alternator though to make sure its in properly, the brushes get worn and if yours has never been changed thats the most likely reason,

before mine was at about 13.7 v after at 14.4

[twoscoops]

Ok so if I am searching on eBay, I am just searching for a voltage pack for an e30? Any pictures of what it looks like? If I am searching German eBay do I not need to write in German??

[bmw9818]

Look at the side of your alternator you'll see a black thing with two screws check the PN, mine was 1197 something if it's that io send u a link

[Grrrmachine]

While this is all good advice, wouldn't it be better to wait until the problem has been diagnosed before rushing on to eBay and buying parts?

[bmw9818]

Obv get a voltmeter and check the voltage first to see if it's that

[genozide]

Another area to look for would the audio amplifier as it happened to my car although it was remote wired.

Turned out one of the audio amplifier was the cause of battery charge drainage.

Changed the amplifier and the problem is gone for now.

[twoscoops]

The volt meter is in the post as we speak so hopefully I can work out how to use it from the link posted above.

Regarding the audi amplifier....where is that found and how do i check it? The car is completely standard apart from a basic sony radio cassette deck.

[Rtaylor2208]

Do you mean audio amplifier? You would know if you had one. It would be seperate to the headunit and usually used to run a sub or more power to the speakers.

[twoscoops]

nope dont have one of those....one less worry.

[twoscoops]

Volt meter arrived yesterday so hopefully get a look at this over the weekend. The battery isnt currently in the car as I dont want to put it in until I am ready to try and find out what is draining it. Should I have any concerns with having the battery out of the car for a couple of weeks. It is a brand new battery.????

[bmw9818]

I'd say just test your alternator first, start it and Check the charging rate

[twoscoops]

just for the newbie that I am, this is done by attaching the voltmeter to the battery before and then starting to see if the alternator is providing charge??? Never had any dealings with charging before so all new.

[bmw9818]

Yep just start the car, and on the battery usual red prong 2 positive, black to negative should get a reading of about 14.4 ish if alternator's healthy

[twoscoops]

brilliant thanks mate!

[Speedtouch]

With a charged battery connected and the ignition completely off you can put a multimeter across the terminals and meausre the amps for drainage.

This should come back with a reading of about 0.1A, but hopefully someone can confirm this as I can never quite remember.

Connecting a multimeter directly across the battery in amps range is a sure-fire way to kill the multimeter, or at least blow the fuse in it! You need to disconnect the battery terminal and connect the multimeter in series between battery and terminal (observing correct polarity), then test with the ignition and everything switched OFF.

It should read a drainage of no more than 100mA (0.1A) or so.

But yes, to measure the battery voltage, put the multimeter on a range of 20V and connect direct across the battery. They are nominally 12V but the charging voltage is around 14V or so.

[twoscoops]

Ok so I put the battery in tonight and when the ignition was off it was reading 12.58v and with ignition on it was 14.17v which would suggest that the altenator is ok...no??

What should I be checking next then???

Cheers

Tim

[Rav335uk]

You need to disconnect the battery terminal and connect the multimeter in series between battery and terminal (observing correct polarity), then test with the ignition and everything switched OFF.

It should read a drainage of no more than 100mA (0.1A) or so.

But yes, to measure the battery voltage, put the multimeter on a range of 20V and connect direct across the battery. They are nominally 12V but the charging voltage is around 14V or so.

[Brianmoooore]

You need to disconnect the battery terminal and connect the multimeter in series between battery and terminal (observing correct polarity), then test with the ignition and everything switched OFF.

It should read a drainage of no more than 100mA (0.1A) or so.

Disconnect the battery negative/earth lead, not the positive one (ever seen a 13mm spanner glow red hot?).
A drain of 100mA is very much an upper limit. 30mA would be more typical.

[twoscoops]

Right sorry I know I am probably being completely thick and missing the obvious but I need to get this right.

Take the negative lead off but leave the positive connected. Then apply the red lead of the multimeter to the battery and the black to the connector??? Then set to amps and start the motor... is that correct or am I a plank??...don't answer that, it's my first time using a meter.

[kam-325i]

!!!!!!!!!!!!!!!!!!!!!!!!!!DO NOT START MOTOR!!!!!!!!!!!!!!!!!!!!!

[kam-325i]

red lead of meter to - on battery
black lead of the meter to the lead you took off the battery
set meter to amps.

everything OFF, including ignition.

[twoscoops]

Ok so everything else and don't start motor?

[twoscoops]

That's great thanks for a nice clear explanation. I will give it a bash tomorrow.

[kam-325i]

everything off.......

[Brianmoooore]

One other point - everything off includes having the doors shut, so I recommend opening the window first. Some alarm/immobiliser/remote locking systems will be triggered if the battery is disconnected and then reconnected.
You wouldn't be the first to find themselves locked out of their car.

[Speedtouch]

red lead of meter to - on battery
black lead of the meter to the lead you took off the battery
set meter to amps.

everything OFF, including ignition.

Ideally, you should put the black multimeter lead to battery '-' and the red lead to the car's earth terminal, else the multimeter (assuming digital) will read a negative value. If it's a moving coil multimeter, connecting it the wrong way round could damage it.

Try it on a fairly high amps range first (0-2A, say), then progressively reduce to the 0-200mA and 0-20mA range as required. You need to take care in these lower amps ranges, else you can easily blow the multimeter's internal fuse (though it is replaceable).

[Brianmoooore]

Ideally, you should put the black multimeter lead to battery '-' and the red lead to the car's earth terminal, else the multimeter (assuming digital) will read a negative value.

I don't think so!

[twoscoops]

sorry, which is the right way round chaps as there seems to be differing advice??

black to '-' or red to '-'????