Marlon

Mine appears to read halfway between 13 and 14 - and yours???

GulleyGulley

About the same - 2004 C2

C4CRNA

Mine starts at 14 and drops between 13-14 after a few minutes driving.

himself

Close to 14 on both my 996 and GT3. Looking at a clock face, it would be the hour hand at 9:45-10:00 with no accessories on. Underload, it get's closer to 9:30.

-td

ivangene

9:30 is WAY past beer-o'clock

quickxotica

Follow up question: What does this gauge really indicate? Is it how much voltage the car is currently using, or how much voltage-capacity is still available (net of current usage)? Is the reading taken at the battery or the alternator?

Mine is always roughly the same as others have posted above.

AmirShaikh

Actually neither...it's showing what voltage the electrical supply (battery + alternator) is providing at that moment. You could take it at either the battery or alternator and it would be the same.

The voltage varies based on health of battery, health of alternator, engine RPM (assuming it's started), and electrical load at the moment (aka what stuff is on). Voltage drops when system cannot supply the required current needed (aka low RPM, highbeam + rear defroster on).

So car off..you should see 12V. Turn on accessories, you may see a drop if battery cannot supply current at 12V.

Crank the car, voltage will definitely drop.

Once car is started, alternator voltage is higher which lets the battery charge...13.5V to 14.4V (operating range for our cars may be different - have to check). If it goes outside of this range, the alternator and/or battery is getting (or is) bad.

Marlon

Then if my battery checked at 12.23 volts this morning and my voltmeter reads about 13 - 13.5V, my alternator is probably OK? The read the alternator at 13.3 or something and it was suggested to me that it was on the 'lo' side.

Steven B

Marlon, If your battery really started at 12.23 V this morning (yesterday, obviously!), your battery is close to being dead. Were you using a good multimeter? (I would not suggest using the dash instrument unless calibrated.) I might have the battery "load-tested" and if it comes out fine, check alternator.

Marlon

Yes, I used a handheld mulitmeter. Last night it was 12.29. The battery in the car was brand new 2 months ago. Maybe I'll go ahead with my alternator R&R. I notice that the alternator is pretty exposed to the elements - how come there's no 'cover' over it to prevent drenching in rain, etc. I had a 120K mile 99' Range Rover that had to have a new alternator at 90K miles - why? Because the passenger-side windshield washer hose became disconnected from the washer jet and for about 4 months was squirting washer fluid directly on the alternator whenever I used the washer system (about once a week - maybe). (shame on me for not investigating loss of windshield washing ability during that time). Anyway, the electrical system 'failed' and the cause was: dead alternator. Gotta' be a way to fab a simple cover for the alternator while not affecting cooling air flowing over it and prevent drenching. My guess is that the 996 alternator will last longer. I am going to get some thin sheet aluminum and see if I can fab a tasteful cover during my alternator R&R.

wwest

Useless...

To be really usefull it needs to be digital or have an even tighter "span", say of only 12-14 volts.

Marlon

Would not the battery be 'overcharged' at 14 volts? On what kind of car do you find a 14 volt system? Your logic suggests that maybe 15 or 16 volts would be even better?

C4CRNA

Marlon: Didn't the reman engine come with a new alternator?

Marlon

Yes it did - BTW: according to the charging system diagnostic just NOW: my alternator is putting out 13.98V/12.8A NO load and 13.720V/9.6A under load. During cranking the system draws 10.27V/264.7A over 1.78 seconds. The battery is 3 months old and after charging at Advance Auto (for free) it reads 12.84V / 675CCA/rated at 700CCA at 74 degrees. My battery and charging system is fine - whewww~!

goliver

Close to 14 for me. Never really moves.