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Old 08-31-2011, 12:20 PM
Calicoastin Calicoastin is offline
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Location: East Bay/Peninsula, California
Join Date: Jan 2009
Posts: 179
Mein Auto: 2003 E39 540i auto
Exclamation Replacing Alternator on my 540i..Any tips?

Well...the battery light came on while on my way home from work yesterday. I already ordered the alternator (Watercooled), should arrive tomorrow. I already sourced a diy ( ).

I think I got this down but wanted to know if anyone thats done this task before has any tips.

I narrowed it down to the alt because:

Battery is fairly new, replaced it in Feb 2010
Battery volt with car off: 12.2 volts
volts with car on & idling (after 1 min): 11.79 volts
volts with car on and approx. 3k RPM: 11.78 volts

So it seems like the alternator isn't charging the battery. I guess it's due anyway (106k miles, 500watt amp on board with 5 farad cap.)

So..Any tips? I appreciate any help/insight..Thanks.

Last edited by Calicoastin; 08-31-2011 at 12:58 PM.
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