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E46 M3 (2001-2006) Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006.


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Old Sat, Dec-02-2017, 03:57:34 PM   #31
den_bart
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Default Re: Possible bad alternator?

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Originally Posted by daytonaviolet View Post
plus he sold the m3 years ago but i believe the his AE was causing a battery drain. once removing/fixing it, problem solved.

den_bart, 12V is low when running. why not swap out with another battery and measure again while running.
I swapped, my battery with a Wal-Mart one and its reading 12V still. When initially starting the car the voltage of the battery increases slowly up to 13V and this only happens sometimes. And sometimes it just stays the same voltage. It seems like the alternator is trying to charge but gives up over time.

Just a note, I have my angel eyes tapped to the interior lights and the engine wire. Im not sure if this may be a culprit. Even without the lights plugged in its still the same.

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Old Sat, Dec-02-2017, 10:22:26 PM   #32
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Default Re: Possible bad alternator?

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Originally Posted by den_bart View Post
I swapped, my battery with a Wal-Mart one and its reading 12V still. When initially starting the car the voltage of the battery increases slowly up to 13V and this only happens sometimes. And sometimes it just stays the same voltage. It seems like the alternator is trying to charge but gives up over time.

Just a note, I have my angel eyes tapped to the interior lights and the engine wire. Im not sure if this may be a culprit. Even without the lights plugged in its still the same.

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Your voltage regulator should put out 13.9V-14.1V.
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Old Sun, Dec-03-2017, 06:21:58 PM   #33
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Default Re: Possible bad alternator?

Is it my voltage regulator then?

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Old Sun, Dec-03-2017, 06:55:39 PM   #34
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Default Re: Possible bad alternator?

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Is it my voltage regulator then?

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If there are no odd bearing noises then the chances are high that your VR is done for. You can remove it from the back of the alt and visually inspect the brushes. Theyre allowed to be a minimum of 5mm, new is 12mm
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Old Sun, Dec-03-2017, 10:04:16 PM   #35
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Default Re: Possible bad alternator?

Ok so reading the voltage from the cluster, when the car is off the batt is good and reads 12V+. When the car runs its reading 13.7-13.8V. So im thinking it might be a connection issue?

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Old Wed, Dec-06-2017, 08:40:55 PM   #36
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Default Re: Possible bad alternator?

also, the op switched out the other rings and put back the Orion V2 and didn't have a battery drain...fwiw - before the car was sold.
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Old Wed, Dec-06-2017, 11:22:41 PM   #37
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Default Re: Possible bad alternator?

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Your voltage regulator should put out 13.9V-14.1V.
My alternator died last year and I replaced it with a Bosch unit from FCP.

Torque/OBD shows it running at between 13.6 to 14.0 with most of the time at 13.8.

Normal or should I get it replaced?
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Old Thu, Dec-07-2017, 06:20:02 AM   #38
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Default Re: Possible bad alternator?

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My alternator died last year and I replaced it with a Bosch unit from FCP.

Torque/OBD shows it running at between 13.6 to 14.0 with most of the time at 13.8.

Normal or should I get it replaced?
Youíre okay. Itís the 12s and lower that start to Drain the system
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Old Thu, Dec-07-2017, 04:26:00 PM   #39
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Default Re: Possible bad alternator?

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Originally Posted by den_bart View Post
Ok so reading the voltage from the cluster, when the car is off the batt is good and reads 12V+. When the car runs its reading 13.7-13.8V. So im thinking it might be a connection issue?

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when the car is running and you remove the gnd of the battery.. does the car continue to run? what if you raise the rpm?
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Old Sun, Dec-10-2017, 04:31:59 AM   #40
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Default Re: Possible bad alternator?

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when the car is running and you remove the gnd of the battery.. does the car continue to run? what if you raise the rpm?
So I took off the neg ground from the battery while the car was running and the car still worked. It was slightly hesitating to turn off but it kept running. Although, my radio turned off. When I pressed/held the accelerator it seemed to kick in more power from the alternator and it did not have trouble running; the radio turned on as well from doing this.

It seems my alternator is still okay but may need to replace it soon? Or it might be a connection issue since when battery is plugged in, the alternator only charges in the low 13V but when accelerator is pressed/held it goes up to 13.7/13.8.

I tested my other e46 and when I turned on the car the Voltage goes up to 14.2V.
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Discussing Possible bad alternator? in the E46 M3 (2001-2006) Forum - Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006. at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)