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Discussion Starter · #1 ·
Just wanted to get some opinions hopefully through experiences. My battery light is on and off as I drive. It just recentley didn't start the other week so I charged it and it was starting fine for the next 2-3 days. It runs fine and starts fine after the charge but Im guessing it doesn't hold the charge properly. The manual says it could be the "alternator drive belt" or a "problem with the alternators charge circuit"

Any ideas? thanks boys e46 love all around
 

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First check your battery connections.
Then do the cluster test.
Menu #19 unlocks the cluster
Menu #9 tells you voltage at battery.

If its not getting charged then its something with the alternator.

If its not holding a charge, then likely the battery.

If its off and on intermittently, then it sounds like bad connection.

http://db.tt/e37Zrkmb
^ item 27 on the list for the cluster test.



Sent haphazardly from my HTC
 

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The alternator is driven by the same belt that drives the waterpump, so if the drivebelt was the source of the problem, then the engine would also be overheating very quickly -- within minutes of starting the car.

The same belt also drives the power steering, so you would notice that as the steam billows out from around the seams in the hood, the steering would be nearly impossible to manage.

You can actually OPEN THE HOOD and look at the engine while it is running and see if the belt is doing its job, or not. If not, then there is typically lots of damaged stuff to accompany it.
 

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Discussion Starter · #4 ·
Fuck this site is incredible. I think it's gotta be the battery then. Everything else mentioned is working perfectly: not over heating and steering is normal. And to MPR77 I already did the test and it was reading 12.6 and was stable even while revving the engine and cranking the radio, just wasn't sure if it was too low because the YouTube video I watched for the test was showing around 14.1. Thanks a shit load boys all the best with ur bimmers!
 

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**** this site is incredible. I think it's gotta be the battery then. Everything else mentioned is working perfectly: not over heating and steering is normal. And to MPR77 I already did the test and it was reading 12.6 and was stable even while revving the engine and cranking the radio, just wasn't sure if it was too low because the YouTube video I watched for the test was showing around 14.1. Thanks a **** load boys all the best with ur bimmers!
12.6 volts means your car is running off only the battery and your alternator isn't working at all. 13.9-14.1 volts means your alternator is working properly and is powering your car and the battery is being kept charged. The problem is probably the voltage regulator on the alternator. Worst case, the entire alternator needs to be replaced, but that is rare.
 

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12.6 means the alternator is not working.

The Battery Light is REALLY a Charging System Failure light, it has nothing to do with the condition of the battery -- except that if it remains on long enough it explains why there is no electricity left in your car. The battery's ONLY job is to provide electricity when the car is not running. The PRIMARY job is to operate the starter, the other stuff that are powered is in the category of accessory item, and power to this category is secondary to the job of operating the starter. Once the engine is running, the alternator powers everything, and resupplies the power drained from the battery during the course of operating the starter.

A properly functioning charging system should have a steady voltage of about 14.0 to 14.5 when the engine is running.
 

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I had the same problem. A quick test to determine whether or not its your alternator or battery is to start the car and disconnect the positive from the battery. If the car stays on, your alternator is good. If the car shuts off, that means the only thing powering the car is the battery and your alternator (or something in the alternator) is bad. I just ordered my 120amp alternator off ebay for about 130$.
 

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I had the same problem. A quick test to determine whether or not its your alternator or battery is to start the car and disconnect the positive from the battery. If the car stays on, your alternator is good. If the car shuts off, that means the only thing powering the car is the battery and your alternator (or something in the alternator) is bad. I just ordered my 120amp alternator off ebay for about 130$.
No!

You didn't read this thread, and I understand you're trying to help, but apparently you do not know about the cluster test.

Read post #2 and learn how to do this, you will thank me.

Btw. You're welcome.:D


Sent haphazardly from my HTC
 
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