randomly dead battery! please help!! - BMW Forum

gemnilvr · 11-07-2009, 03:11 PM

ive been having problems for a long time now and no one can seem to properly diagnose the issue! its really frustrating! i am so used to having my car jumpstarted that it seems to be part of owning and driving my car! now ive noticed that the ignition is a little off! when i turn the key there is about a one second pause before it starts the car! if i do it slowly or dont hold the key in start possition long enough and then try and restart the car it wont turn over it will make a clicking sound at first then the more i try the clicking eventually stops and does nothing as if i have a completely dead battery! the thing is it will then jump start everytime and then not happen for a week or more or it could be the next morning! its so random! im totally lost and not sure what to check next! if anyone has this problem and fixed it i would love to hear from u or if anyone has any suggestions it would be great! im wondering if the ignition switch is going bad and if it can cause the battery to do this! can jumping the car bypass the ignition switch and start the car!?

marti5 · 11-08-2009, 05:00 AM

Time for a new battery ????

DonJ · 11-09-2009, 11:44 AM

you might have something draining down the battery which could lead to making your battery go bad - batteries don't like to be charged, drawn down, charged, etc.

have your alternator checked - bad diodes can run a battery down.
have your battery checked out at the same time - chances are it is bad.
a lot of car parts places will check battery and alternator for you free of charge.

if you replace your battery and it goes dead on you again, then you also might have some sort of electrical problem else where that is draining your battery.
You didn't list your car model but if you do a google search - you might find some more answers. For instance - if your BMW is an E34 - google "battery drain e34" - you'll find links back to this forum as well as others.

gemnilvr · 11-09-2009, 12:11 PM

Quote:

Originally Posted by DonJ

you might have something draining down the battery which could lead to making your battery go bad - batteries don't like to be charged, drawn down, charged, etc.

have your alternator checked - bad diodes can run a battery down.
have your battery checked out at the same time - chances are it is bad.
a lot of car parts places will check battery and alternator for you free of charge.

if you replace your battery and it goes dead on you again, then you also might have some sort of electrical problem else where that is draining your battery.
You didn't list your car model but if you do a google search - you might find some more answers. For instance - if your BMW is an E34 - google "battery drain e34" - you'll find links back to this forum as well as others.

Yeah autozone checked the alt and the battery and said they were good, the battery is only 2 years old. I was having probs with a dead battery b4 bcuz of the fsu needing replaced so I did the diy on that and replaced the battery. I do know that I have a faulty alarm system as well that would go off all the time and drain my battery so I can't use the alarm or even lock my car anymore! I just wonder if it could be a bad ignition switch that is killing the battery? It's weird bcuz I can drive and start my car fine all day then for no reason it will just click and not start and eventually the clicking stops and everything is dead and a few times the computer is even messed up and will read -40 utside temp and slowly climb back to the right temp after I've been jumped and drive for awhile!? It's too expensive to have the dealer diognose the prob. They may never find out the reason! Any more thoughts? It's an e39 530i 2002

DonJ · 11-09-2009, 12:28 PM

it is possable that the ignition switch is bad but there are other things that can cause this. You've already taken care of the dreaded fsu problem.

Try googling E39 batter drain or E39 battery drain ignition switch - you'll find more info than you really want :-)

gasman1 · 11-12-2009, 03:30 PM

had the same problem , changed the battery but after a couple of months the car was dead , took it to my locol specialist they had the car for a few hours so they could check it out , it turns out it was the heater sensor and it was turning on when car was not in use , apparently it has happened on a few cars . good luck as it drove me mad

DonJ · 11-12-2009, 08:18 PM

heater sensor? What exactly is that and where is it? I've never heard of it but it sounds like it is something to look in to if I have problems like this.

Thanks!

gasman1 · 11-16-2009, 12:49 PM

not sure where it is , the guys that done the work explained that it was making the air blower come on when the car was locked up and not in use

Bimmermann · 11-18-2009, 08:59 AM

Hi DonJ:

If you have alarm problems, did you physically disconnect the wires. Otherwise, whether you use it or not it will be drawing and discharging the battery, specially if the alarm has a malfunction.

This should be the first thing you should look, before seeking alternative causes.

Bim

wayne adesso · 12-11-2009, 11:40 PM

Have you tried looking at the starter? There is alot of power going to that unit in order to turn over your engine ,could be shorting out at the selonid and draining your battery.just a thought. Good Luck.

wayne adesso · 12-19-2009, 03:09 PM

Up-date, there is a switch in the climate controll called a FSU (final stage unit} That is known to fail and cause Batt. drain, Check out Bimmerforums and see thread called
Battery Drain.
Tamstar.
Might be related to your problem.Good Luck

witeshark · 12-19-2009, 03:13 PM

Thanks for posting that!

wayne adesso · 12-19-2009, 04:27 PM

Your Welcome Witeshark,Ive found out how tough it can be to figure out seemingly simple problems with Bimmers,Not quite like fixing the old chevy.Anyway Im just passing on information gleaned from various forums and DIYs. Standing on the shoulders of giants you might say.
Wayne..

fiama · 12-23-2009, 02:02 AM

Test the charging system with a Voltmeter. With the car running put the multimeter on a DC Voltage range greater than 14 Volts and touch the probes to the battery terminals.

dimbim · 02-16-2010, 04:40 AM

I have a similar sounding problem if doing lots of short journeys.
The gel batteries don't charge at a high rate, so they need careful recharging with a special charger if flat, and I charge mine from time to time to keep it in good condition.
I have switched off the interior lights and this helps alot. Press and hold the main light switch until it goes off, then it will stay off.