The old alternator was reading around 14.5 cold and only 13.1-13.4 volts with a warm engine and I was also having the problem with the guages flickering and trip odo resetting itself to zero due to a low battery (99 tsb bulletin). This was before the asp install. Now, with the asp pulley and new alternator, it reads around 15 on cold starts, but it drops at around 13.6-13.7 volts after it's fully warmed up and running. However, my battery stayed charged at around 12.8. Is this normal for the alt voltage to drop after the car is fully warmed up? For the A4 cars with asp pulleys, where does your gauge read at idle and what's considered acceptable? Any help is appreciated.

 

normal for the voltage to drop, as the alt has already recharged the batt. from the cranking discharge, your warm voltage looks good, and the batt. voltage is good, if a little high

 

You know they make an alt pulley to compensate for the smaller crank pulley right?

 

I'm aware of an alt pulley, but held off on it since i don't have any aftermarket components to help drain the battery. Thanks for the info.

 

Your car was designed with the stock alternator output in mind, in putting an underdrive pully your car is now running with less voltage than design intended as you are now experiencing.

 

I figured it was the underdrive pulley, but wanted to make sure since I had problems before installing the pulley and new alternator. So far, the alternator is doing it's job keeping the battery charged. I appreciate the help.

 

Its doing the job but having to work harder at it.

 

^True, but I will hold off on the alt pulley for now, unless I get more electronics and/or the alt dies earlier than expected.