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-   -   Battery keeps draining. (http://www.bimmerfest.com/forums/showthread.php?t=657988)

Joeedawg1911 11-13-2012 03:52 PM

Battery keeps draining.
 
Story goes: I was working on my car and after I was finished I drove it around. Parked it and finished up. Well in the process of finishing up and leaving I left the lights on. *Dunce cap* Which obviously drained my battery. I got a jump start and figured the alternator would charge up the battery while I drove around town for a couple hours. Well, it didn't hold a charge for anything and needed to be jump started the second I turned the key off. So I figured I needed a new battery. (This one was getting old anyways) 1 day later with the new battery installed and having drove around all day...it's dead too. So I'm thinking, well ****. Maybe the alternator crapped out on me and that's why the first battery wouldnt hold a charge. So I shell out some more money on an alternator and change it out myself. Get a jump start again and BAM it's working like a champ.....4 hours later I'm back at square one. The battery is dead. So I'm stuck. I've read around and people have said perhaps something is draining the battery? I don't see that being the case because before this whole deal the battery was just fine. Little help? Advice?

charlesberry 11-13-2012 04:05 PM

This video walks you though how to diagnose a draw on the battery when the car is not running. Hope this helps.

http://www.youtube.com/watch?v=KF1gijj03_0

Joeedawg1911 11-13-2012 07:00 PM

11 mili amps...so there isn't a draw going on it seems.

GoForthFast 11-13-2012 09:44 PM

You can't put on an alternator with a dead battery and expect it to come back enough unless you drive across the state.
Each time you take a battery to dead zero, you kill a bit of it.
Get a charger and slo charge your new battery to see if you can get it to come back.

joegr 11-14-2012 06:29 AM

Quote:

Originally Posted by GoForthFast (Post 7193729)
You can't put on an alternator with a dead battery and expect it to come back enough unless you drive across the state.
Each time you take a battery to dead zero, you kill a bit of it.
Get a charger and slo charge your new battery to see if you can get it to come back.

That, plus use a voltmeter (or the dash diagnostic feature) and measure the electrical system voltage while the engine is running. If it doesn't stay between 13.6 and 14.5 volts, you have a charging system problem still.

jvr826 11-14-2012 07:53 AM

Outstanding contribution to the site Charles!

nivo 11-14-2012 10:34 AM

Once completely dead a 100% discharged battery will need a slow charge to bring it back. 24-36 hours is not uncommon but sometimes they are just too far gone.
might want to check the battery with the car off and see if it has a drain, for some cars you will need to wait 20 minutes or so to wait for the ECU/DME to go into "sleep" mode (there timers/delays in some circuits). After the 20 minutes or so you will have your actual drain. see how many milliamps it is drawing, the alarm and blinking light do drain some but not enough to kill the battery.

Another thing, long gone are the days of the single wire alternators, today most high end cars even some in the 80's to now have an exciter wire or communication intarface wire that either goes from the ECU or to the gauge cluster, if this wire is no good due to a rodent chewing on it well, the alternator will not charge.

Last but not least, MAKE SURE YOUR GROUND AND ENGINE GROUND ARE GOOD!

my05crf280 11-14-2012 12:21 PM

I would put the multimeter on the battery terminals set for voltage and check the voltage at rest with the car off and with the car running. see if the voltage jumps to normal charging voltage.

Joeedawg1911 11-15-2012 10:47 AM

Quote:

Originally Posted by joegr (Post 7194017)
That, plus use a voltmeter (or the dash diagnostic feature) and measure the electrical system voltage while the engine is running. If it doesn't stay between 13.6 and 14.5 volts, you have a charging system problem still.

I saw a youtube video for that. He said go to test 19 then 9. It reads around 12.3 with a fully charged battery. Then the next day when I drive it with a fully charged battery, it dies on me after X amount of time driving. I know it's dying because my light go dim and my airbag light comes on, radio goes dead and same with the heater. The second I park it and turn off the engine it's dead. I take a reading of the panel (test 19, option 9) and it reads 6 or 7. So at some point the battery gets drained.

So I don't know what to think anymore. When I did the battery drain check it showed it was within limits(11 mili amps) but maybe thats not the case. Perhaps there is something draining the battery at night and the charger system isn't working as well? I have the new battery slow charged up. My new plan is to throw the new one in. And when I park the car I'm just going to keep disconnecting the battery. If it stays charged up after a week or two then i'll know 10000000% that the battery is getting drained at night. That's the only thing I can think of for now until the weekend to break into it more.

Side note: Shouldn't the alternator have enough juice to supply power to the headlights WITH the engine running when my battery dies?

joegr 11-15-2012 11:47 AM

Okay, you're looking in the wrong direction. If it dies while you are driving, as described, it's not a parasitic load at all. It's simply that the charging system isn't working.

You didn't do the test that I wanted you to do. What I wanted you to do was to monitor the voltage while your were driving, not before and after but while. While you are driving it should be around 14. Clearly from your description, it is not.

It could be your alternator (even though it is new), it could be the voltage regulator (if you didn't change it with the alternator), or it could be a wiring problem.

The answer to your last question is yes. The alternator can and must provide enough current to run all the loads on the car and charge the battery at the same time. While the engine is running, there should never be any current drawn from the battery.

Joeedawg1911 11-15-2012 02:52 PM

Drove around with the car. Monitored the voltage and it stayed put around 14 while driving. Max it ever got was 14.1 lowest was 13.3-13.5 when standing still at a red light.

joegr 11-15-2012 04:52 PM

Quote:

Originally Posted by Joeedawg1911 (Post 7197214)
Drove around with the car. Monitored the voltage and it stayed put around 14 while driving. Max it ever got was 14.1 lowest was 13.3-13.5 when standing still at a red light.

13.3 is a little low. I'll bet that if you keep watching it, you'll see it sometimes drop below 12 while driving. Maybe you have a marginal connection somewhere.

Joeedawg1911 11-15-2012 05:30 PM

Quote:

Originally Posted by joegr (Post 7197409)
13.3 is a little low. I'll bet that if you keep watching it, you'll see it sometimes drop below 12 while driving. Maybe you have a marginal connection somewhere.

I turned everything on. Radio/heater/headlights/fog lights/dash panel lights all the way up. Driving down the road it went down to 12.3-12-5. Seems like my headlights are drawing a lot of power when turned on? Not 100% if that sort of drop is normal? When I turn them off it jumps up about .4-.5 ish. With everything off besides the radio it was rock solid but that might of been because It was early in the day and I had just got done trickle charging the battery the day before. So far it hasn't dropped below 12 but I'm keeping my eye on it. I called BMW and set up an appointment just in case I can't figure this out by the 26th. I'm going to drive it one more time tonight and see where it's at. If it drops below 12 this last time then it's def not getting a charge.


Thanks for all the help so far though guys! I appreciate it.

joegr 11-15-2012 06:02 PM

Quote:

Originally Posted by Joeedawg1911 (Post 7197484)
I turned everything on. Radio/heater/headlights/fog lights/dash panel lights all the way up. Driving down the road it went down to 12.3-12-5. ...

That's way too low. Your charging system is not working. Don't keep playing around with this. You are taking a lot of life out of your new battery. If you can't troubleshoot and fix this yourself, take it somewhere now.

my05crf280 11-16-2012 11:35 AM

for short term current draws like stereo equipment your alternator will never be able to be the sole supplier of the current needed. at least with higher end systems drawing 200+ amps. short term demands are definitely drawn from the battery and capacitors (if being used.) along with of corse the alternator. if you were to disconnect your battery your car will still run off just the alternator. turn up a stereo that truly draws 200+ amps and it will definitly shut off your car when the alternator cant keep up. but as stated. your charging system seems to be the issue and putting it off will put unnecessary demand on your battery.

jvr826 11-17-2012 10:44 AM

I did this test today and read about 2.9 mA draw when the car is asleep. Seems I'm good in the parasitic drain department.

GoForthFast 11-18-2012 09:08 AM

I'm happy that you report no parasitic drain.
However that 2.9ma reading is suspiciously low. I'm surprised because I think the resting current should be a little higher.
Do you have the factory alarm working?

jvr826 11-18-2012 09:53 AM

E46's do not come with a factory alarm. It was a dealer installed option which I do not have.

GoForthFast 11-18-2012 10:11 PM

Did not say factory installed. It is manufactured in the factory and the main part is installed there. All that is added in the field is the siren, motion sensor, and tilt sensor. I installed mine so I know all the details.


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