All,

Yesterday I installed an alternator that I rebuilt about a year ago.

On initial startup I read 11.56 Vdc at the battery with the lights on.

I went and turned the lights off and while doing so the car hesitated, but did not die, and then recovered.

When I checked the voltage again I was getting 13.59 Vdc, definitely charging, but below the Bentley manual specification of 13.8 - 14.8 (VDC)

My question is this, is there a potential break in period for the new brushes to fully mate with the new copper ring that I placed on the alternator?

Thanks in advance,

Matt

Here's my guess Matt...

The belts were slipping when the voltage was below 12V because the alternator's load is at its maximum just after starting the car. Your belts were slipping without making noise or you would have mentioned the typical squeal.

Once it began to charge your reading was OK. If the Bentley were to quibble about millivolts here, it would specify the temperature and where your probes belong. Check for voltage drop between B+ terminal and battery positive post; alternator frame ground bolt and battery negative post. This, and temperature of the regulator module is where the millivolts matter.

This chart just shows how the temp affects voltage...





--
Art Benstein near Baltimore

Real Engineers consider themselves well dressed if their socks match.
Real Engineers buy their spouses a set of matched screwdrivers for their birthday.
Real engineers have a non-technical vocabulary of 800 words.
Real Engineers repair their own cameras, telephones, televisions, watches, and automatic transmissions.
Real Engineers say "It's 70 degrees Fahrenheit, 25 degrees Celsius, and 298 Kelvin" and all you say is "Isn't it a nice day?"
Real Engineers wear badges so they don't forget who they are. Sometimes a note is attached saying "Don't offer me a ride today. I drove my own car".
Real Engineers' politics run towards acquiring a parking space with their name on it and an office with a window.
Real Engineers know the "ABC's of Infrared" from A to B.
Real Engineers know how to take the cover off of their computer, and are not afraid to do it.
Real Engineers' briefcases contain a Phillips screwdriver, a copy of "Quantum Physics", and a half of a peanut butter sandwich.
Real Engineers don't find the above at all funny.

Art,

Just did the voltage test:

13.6 Vdc at the battery terminals,

14.2 Vdc at the alternator terminals

I have a .6 Vdc drop from alternator to battery.

Any thought on where I should start to regain some of that lost .6 Volts, or is this good enough?

Thanks,

Matt
--
1989 - 245, 1990 - 245, 1991 - 245, and 1993 - 245

Art,

Thanks!

I thought about the voltage drop on Sunday after installing it and seeing what I saw, but was just wiped from the amount of time it took me to do this, and the fact that it was just so dang hot out.

I'll do this test sometime this week and report back.

Matt