Go Back   986 Forum - for Porsche Boxster & Cayman Owners > Porsche Boxster & Cayman Forums > Boxster General Discussions

LinkBack Thread Tools Display Modes
Old 09-07-2014, 04:06 PM   #1
Registered User
amagalla's Avatar
Join Date: Nov 2009
Location: San Jose , CA
Posts: 519
Alternator dying?

Hello all,

I've been investigating the source of some alternator whine that I have coming through my stereo. With the car at idle, I checked the voltage at the battery. It's seeing only 13.65 volts. This seems a bit low to me, but I don't know enough about the Porsche alternators to say for sure. So I pose the question: Is my alternator dying?



Lapis Blue 03 Boxster S
Seal Grey 04 Boxster S (RIP 9-21-14)
amagalla is offline   Reply With Quote
Old 09-07-2014, 04:25 PM   #2
Registered User
Steve Tinker's Avatar
Join Date: Dec 2008
Location: Queensland, Australia
Posts: 1,522
No, @ 13.6 v, that's OK for a fully charged battery condition.....

A better (quick) test is to check you battery voltage after the car has sat for an hour or so - a fully charged battery should indicate 12.6v. Now start the car for a few minutes and check the voltage again @ idle which should indicate your 13.6 v. Increase the revs to +/- 2,000rpm and see if the voltage rises to +/- 14.0v to 14.5v, steadily dropping as the battery reaches a fully charged state.

A fully charged battery will show only about 13.5v charge from the alternator but a low charged battery will show over 14v from the alternator.

Alternators will whine when under load and rumble when the bearings are worn.

2001 Boxster S (triple black). Sleeping easier with LN Engineering/Flat 6 IMS upgrade, low temp thermostat & underspeed pulley.
2001 MV Agusta F4.
Steve Tinker is offline   Reply With Quote

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

All times are GMT -8. The time now is 10:00 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page