Alternator voltage low

lilredpo · 05-31-2011, 06:10 PM

2002 Boxster S. 'Battery / Generator' as well as other flashing messages. Replaced battery. Voltage now reading 12.5 across battery with key off. Running, voltage reads 11.41 at high rpm as well as at idle.

Everything I have read points to a failed alternator if running voltage reads over 15/16.

Should I assume alternator is bad with low reading or should I look for other issues?

TIA.

JFP in PA · 05-31-2011, 06:32 PM

You have a bad voltage regulator.

turboflyer · turboflyer's Garage

+1 on the regulator. Get a replacement regulator and replace it yourself. Not hard to do at all. You will have to remove and reinstall the alternator. Should cost about 50 to 75 bucks. Check the diodes and fields as well to ensure everything else is healthy.

DCinVA · 06-01-2011, 06:40 AM

+2 on the regulator.

Some interesting/helpful reading here.
http://forums.pelicanparts.com/porsche-996-997-forum/408495-alternator-repair-regulator-replacement.html

Wayne 962 · Wayne 962's Garage

See this thread here too: Battery Light On - 101 Projects to the Rescue!

-Wayne

JMatta · 06-02-2011, 05:15 AM

Yep, my car was not putting out the required voltage. I replaced the regulator per my post and problem solved. Drove the car 250 miles last weekend and not a single issue.

lilredpo · 06-02-2011, 05:48 AM

Great, thanks everyone. I will post when back on the road!

JMatta · 06-02-2011, 08:18 AM

Have fun removing the alternator...wear some mechanic's gloves, as I scratched the heck out of the back of my hand trying to wiggle the sucker out of there; it really does help to remove the passenger seat to gain access/leverage. Per Wayne's book, you do need to rap the pulley bolt to loosen the rear bushing or you won't get it out. Good time to consider belt condition, since you need to release the tension.

JMatta · 06-02-2011, 09:11 PM

Good news...Pelican now has the voltage regulator in the catalog!

Pelican Parts - Automotive Parts and Accessories - Porsche & BMW

lilredpo · 06-10-2011, 04:48 AM

Thanks for everyone help! I replaced the alternator, as opposed to just the regulator, did notice it is a little quieter. Now running well. Did belt and detailed engine while in there. Very straight forward and relatively easy job thanks to Pelican and the boards. Took longer to gain access and close than it did to replace alt and belt, buit recommend to any shade-tree mechanic.

Thanks again all!