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Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 3 Series / 4 Series > E46 (1999 - 2006)

E46 (1999 - 2006)
The fourth generation 3 Series (E46 chassis) was introduced in 1999 and set the standard for engineering and performance during it's years of production including being named to Car & Driver's 10 best list every one of those years! ! -- View the E46 Wiki

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  #1  
Old 11-10-2012, 12:40 PM
nfsplayer2 nfsplayer2 is offline
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Location: new jersey
 
Join Date: Jul 2011
Posts: 82
Mein Auto: 2001 bmw 325i
Alternator not putting out enough amps.

I have a huge problem with alternator and voltage in my bmw e46 325i.

Little back ground about the problem:

I put a little system a while back. First amplifier was 1200watts and alternator was keeping up with it. I also upgraded my battery to kinetik hc1800 so everything was going good.

After few months I upgraded amplfiier to 2500watts (it pulls ~250amps) and the battery to xs power D3100. One day after picking up my car from good year (took it for suspension check) my voltage was pretty low, ~13.5-13.7v. But eventually it went back up to 14v.

So I decided to upgrade my alternator to a high output one, 260A. When I pulled the original alternator out, it was locked, wasn't turning at all. When I put the 260A in, the voltage was around 13.8v at idle and 14v at 2k rpm. BUT, when I put a load on it, like rolling windows up, the voltage would drop down to ~13v and climb back up. So I thought that the alternator was no good and sent it back to the guy who tested it and it came out to be perfectly fine.

So I ordered another stock alternator which does the same exact thing. As soon as I apply load in it, voltage goes down. Like if I shift the gear into "rear" voltage drops down little bit and climb back up.

I talked to the guy who built HO alternator and he said that it's because of the belt slip. But how can I have belt slip with stock alternator?

What could the problem possibly be? I've checked all connections, charged battery and bought a new belt from dealership.
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  #2  
Old 11-10-2012, 03:53 PM
my05crf280 my05crf280 is offline
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Location: andreas pa
 
Join Date: Mar 2012
Posts: 113
Mein Auto: 2000 323i 5spd
your alternator is merely there to keep the battery/batteries charged. I've been in the audio business for a long time. Ase certified and mecp. its sounds like your amperage numbers are a bit exaggerated but none the less your solution is wrong. with that much current your gonna need more batteries. as they supply the short term draws the stereo or other equipment demand. typically anytime you run a system over 100amps your going to need to upgrade your factory ground to zero gauge or bigger. also the positive from the battery to your amps and the one from the alternator to battery. especially on BMW's with the battery in the trunk. its definitely a good idea to run a higher amperage alternator like you mentioned but for short term loaded like you mentioned you'll need more batteries or even caps. but usually for the money I like to go with batteries.
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  #3  
Old 11-10-2012, 03:58 PM
nfsplayer2 nfsplayer2 is offline
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Location: new jersey
 
Join Date: Jul 2011
Posts: 82
Mein Auto: 2001 bmw 325i
Already have 1 run of 0 gauge to alternator, 0 gauge for ground and amp. The battery I have is big enough for the amp for now.

Right now I'm trying to get the alternator going.
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  #4  
Old 11-10-2012, 06:37 PM
my05crf280 my05crf280 is offline
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Location: andreas pa
 
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Mein Auto: 2000 323i 5spd
I still say you want more batteries. if you insist alternator. did you run a larger ground from the alternator to the chassis?
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  #5  
Old 11-10-2012, 06:38 PM
nfsplayer2 nfsplayer2 is offline
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Location: new jersey
 
Join Date: Jul 2011
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Mein Auto: 2001 bmw 325i
right now I'm working with stock alternator.
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