Charging system issues, electrical gurus your help is needed
 

Just when I thought I fixed the problem, BAM! it comes back. A few of months ago, my battery kept dying. It was the original from '97, so replacing it was justified.

The car would jump and push start fine and with the engine running everything was fine. I could run EVERYTHING electrical simutaneously with no problems. The lights were bright, the radio was loud and the windows rolled up and down quickly.

However after a 50 mile drive, the battery still wouldn't hold a charge. I had it charged for free at Sears twice and eventually bought a the new Diehard that I have now. I didn't think it could be the alternator, since the car ran fine and powered everything with no problems while the car was running. The problem was fixed, so I thought.

So yesterday, I try to start the car and I get two weak cranks and no start! Try it again, two weak cranks. Again, one weak crank and well you know the rest of the story. I jump started it and drove it around for a few miles. Let it run for about 15 minutes and shut it off. Tried to start her up and it did, but it seemed to struggle before it finally cranked over.

What confuses me is that it push starts and jump starts perfectly and when it's running everything is fine. I'm wondering if anyone who has experience with voltage regulators and alternators could possibly shed some light on me.

All of the fuses are fine and I didn't disonnect the battery cables while the engine was running, because I din't want want to risk messing anything up. I did disconnect them when the engine was off though to clean them and make sure they were snug, still no luck. Any advice would greatly be appreciated.

I don't have a multi meter, nor do I know where to check to see if there's a current drain somewhere. So please be specific as to which wires to test and what I should be looking for:confused: TIA

If your car has a weak battery overnight, then it sounds like you have a short. The alternator can work fine, and even charge the battery, but over time, the short will sap your battery power.

What you can do for now, is buy what I bought, a negative battery terminal quick disconnect. I got mine from Pelican Parts. By removing the quick disconnect overnight, you stop the short from draining the battery.

http://img517.imageshack.us/img517/3...ch40188xj4.jpg

Yeah, but I'm not sure that the battery is even getting charged. I mean, it might have gotten a little juice from the 30+ minutes I had the car running, but it was barely enough to crank it over immediately after I shut it down. Thanks L84THSKY, sorry about the long post.

I suggest getting a multimeter (RadioShack has some nice ones). I wish I could help you but I don't really know much about the charging system :(

Cooljess try this, start your car and let it run for like a minute or so, while the car is running unplug the positive cable from your battery (make sure that it does not touch any metal parts, cause if it does you will create a short), if the car turns off them your alternator is done. From what your discribing, I think that is your alternator. If its your alternator and if you can wait 'til the meet I would like for you to meet me and I will take you to a place that specializes in OEM parts and I get a good discount there, if ot go through your usual place and you know what, you can always get a hold of lilblkbmw, he works for a BMW dealer.

Hope this helps you troubleshoot your problem.

Excellent lazoh, I'll try that tonight after dinner. IIRC, somebody said not to hook the positive cable back up while the engine is running because you could fry something, so I'll just diconnect it and see what happens and then shut the engine off before I reconnect it. That is if the car doesn't die on me when I disconnect it.

BTW, If anyone dissagrees with what I'm doing, please speak up because I don't want to blow anything, lol. I'm going to do it in about an hour, so I'll check back here before and then post back with the results.

If you are careful you should be fine and I have done this a couple of times since I had to replace my alternator twice due to sound system issues (too many amps and too much wattage)!!! :biggrin:

I might just do that as a temporary fix until I get things sorted out. I'm getting ready to test the alternator here in a few minutes. Thx for the good idea.

From what you described, it didn't sound like your alternator was bad. I could have suggested what was just mentioned, I have done that too. Do not reconnect the battery while the car is running on the alternator, you could blow the regulator.

You said you could run the car with all the accessories on, and everything was good. At that point, you need to check your battery, if you are running on your battery, you won't be able to keep everything going very long.

After you check out the alternator, and if it's fine, disconnect the negative lead of your battery, and put a multimeter in between the negative cable and the negative terminal. Set the multimeter to amps, and see if any current is flowing. If it is, you have a short. By turning on and off each accessory, you can find what is drawing the current.

That's exactly the advice I was looking for! I searched the electrical section for every thread with the word "battery" and couldn't find anything with instructions on how to chase down a short or if it was safe to disconnect the battery while the car is running. you guys are awesome! Thanks again

The part about disconnecting battery and using a multimeter was for testing with the engine OFF.:cool:

DUDE!!! THE BATTERY BLEW UP IN MY FACE AND THE MULTI METER MELTED IN MY HAND!

J/K, here's what happened;
I jump started the car and turned everything electrical on including the a/c and defroster. I turned the radio volume full blast(RANCID "and out come the wolves") and the car ran fine.

Then I turned everything off and left the car running while I disconnected the positive cable from the battery. The car continued to run fine, I reved the motor a few times, noticed that the clock didn't lose the time and started turning everything on again, this time with the positive cable disconnected. The dome light started to flicker a little, but the car continued to idle smoothly. Last I turned the hazards on and everything started to pulsate each time they blinked. The radio turned off and even the air coming out of the vents started to pulsate with the hazards. The ABS and ASC lights came on and then extinguished by themselves and then came back periodically while I let it run like that for about 10 minutes. Still the engine idled normally, but the electrical system definitely was stressed.

I shut the car off and reconnected the positive cable. I turned everything off before shutting the engine down. The car started back up and I took it for a spin around the block a few times with no problems. Then I came home, let it set for about 30 minutes and went back out to see if it would start and it started right up three times with no problems.

Now I haven't yet disconnected the negative cable and tested the voltage between the cable and the battery with the engine off, but I'll probably do that tonight or tomorrow when my neighbor gets home and loans me his meter. But my question is, so far with the information given, is it normal for the power to fluctuate or pulsate when the positive cable is disconnected and the engine is running with all of the electrical components and a/c and fan turned on? The reason I ask is because after starting the car three times with no problems I'm a little confused as if it is the alternator or a short/drain. Thanks again guys, I can't tell you how much I appreciate your help.

Bro, the flickering is not normal I personally think that your alternator is starting to fail, check to see if you have a short and let us know your findings.

Right on Bro, will do. Thx again!

Anytime bro and hope to see you on the 14th!!! :cool: