986 Forum - The Community for Porsche Boxster & Cayman Owners - View Single Post - What's the typical Boxster voltage while driving?

JFP in PA · 07-08-2011, 01:43 PM

Your alternator is weak, and most likely candidate would be the voltage regulator (which you have indicated you already changed), so the next suspect would be one or more of the diodes are weak. You should be in the low to mid 14 volt range, either at idle or running.

Hydrometer reading is a measure of the battery charge condition, not a measure of the charging system. To find a somewhat weak battery on a car with a below par voltage output is not unusual. Replace the alternator, or the diodes if you are so inclined, and you battery will most likely come back up to snuff, assuming it has no organic issues itself.

07-08-2011, 01:43 PM	#2
JFP in PA Registered User Join Date: Feb 2005 Location: It's a kind of magic..... Posts: 6,608	Your alternator is weak, and most likely candidate would be the voltage regulator (which you have indicated you already changed), so the next suspect would be one or more of the diodes are weak. You should be in the low to mid 14 volt range, either at idle or running. Hydrometer reading is a measure of the battery charge condition, not a measure of the charging system. To find a somewhat weak battery on a car with a below par voltage output is not unusual. Replace the alternator, or the diodes if you are so inclined, and you battery will most likely come back up to snuff, assuming it has no organic issues itself. __________________ “Anything really new is invented only in one’s youth. Later, one becomes more experienced, more famous – and more stupid.” - Albert Einstein Last edited by JFP in PA; 07-08-2011 at 01:46 PM.