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12-19-2009, 10:23 AM

pauliehcfr

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I have a 2004 545i. Can someone check what the voltage is at the battery with the engine running, no accessories on, and let me know what they are getting? I think I have a bad alternator/voltage regulator, but want to compare it before I spend $$$$$$$ for a new alternator. Thanks

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12-20-2009, 08:49 AM

porsche911targa

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My Ride: 2006 525XI, Jet black on Dakota beige. Premium and winter packages. I consider myself a purist and intend to keep my car absolutely stock and shiny. 2008 328I Convertible, Sapphire black on beige interior. Premium package, NAV, iPod adapter. Retired: 2002 325I, Titanium silver on black leather. Premium package. Absolutely stock and proud of it.

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Originally Posted by pauliehcfr' post='1076608' date='Dec 19 2009, 02:23 PM

What is your current voltage at the battery?

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12-20-2009, 11:42 AM

JasonH

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At the charging points under the bonnet you should see around 14.5V with the engine running.

I'd say more that 15V or less than say 13.5V would be a problem.

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12-21-2009, 05:55 AM

pauliehcfr

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Quote:

Originally Posted by porsche911targa' post='1077077' date='Dec 20 2009, 12:49 PM

What is your current voltage at the battery?

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At the battery with key off, around 12-12.5 volts. Engine running at idle, 14.9-15.1 volts. when I blip the accelerator pedal, the voltage spikes as high as 16.8 volts and then returns to the 14.9-15.1 volt range.
I am thinking I have a ba alternator, but want to be sure before I spend the money and time replacing it. I am having problems with the radio sound going out for a couple of seconds and then coming back on, dynamic drive failure occurs at the same time, the interior lights flicker, the a/c blower sounds like it surges on acceleration, and more recently the illumination on the window switches goes off and on. Any help would be appreciated.

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12-21-2009, 06:22 AM

pukka

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My Ride: 2008 535i: (8/07 Build) Metallic Bronze, Beige NASCA Leather, Ventilated Seats, Sport Pkg, Cold Wxr Pkg, Logic-7 Sound, HUD, Night Vision, PDC, Split Rear Seats, NAV, Premium Pkg, Comfort Access, HD Radio, Sport Auto Trans Current mods: M-Aero Kit, JB4, Motorcepts 6000k HID Foglamps Umnitza ICE-Lite 10w LED 6000k AE's 1992 Camaro RS: Fully Restored w/Custom Interior, 5.0L V8, T-tops, OEM Z28 Foglamps, Inst Cluster, & Spoiler, Custom Sound, Too many engine mods to list

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Originally Posted by pauliehcfr' post='1077565

I am thinking I have a ba alternator, but want to be sure before I spend the money and time replacing it. I am having problems with the radio sound going out for a couple of seconds and then coming back on, dynamic drive failure occurs at the same time, the interior lights flicker, the a/c blower sounds like it surges on acceleration, and more recently the illumination on the window switches goes off and on. Any help would be appreciated.

What exactly is the car doing when it acts up? (idling, accelerating, etc). Try running the car with no accessories on, then turn on each accessory one by one while paying attention to the alternator voltage. Turn on the blower motor and headlamps last since they usually draw the most current. If everything runs fine with these two things off then your alt is probably weak and needs to be replaced/upgraded. If things still don't work right then your problem is somewhere else.