Just wanted to see if anyone has had a similar problem. When I start my car up my voltage reading on my dash is about 12volts, which is pretty low. I let it idle and the voltages doesn't move...i check battery voltage and it's reading 12 volts also. I start driving it and after a while all the lights on my dash brighten up and the voltage jumps to about 14.3volts and stays there. I come home and park it for like 5 min. and start it up again and it reads 12 volts. I have a powermaster alternator that i've had for about 3 years...maybe the internal regulator going bad??

 

voltage regulator. depending on alternator it could be on the fenderwell

 

sounds like most mustangs

 

Do you have underdrive pullies? They'll make the alt turn slow enough that it won't charge at idle. Also, the 1 wires have an internal switch whereby the alt rpm has to increase enough for the alternator to turn on. With my March UDP's and Powermaster alt I have to bring the engine up to 1,500rpm when I first start it to get the alternator to turn on.

 

No I don't have underdrive pulleys...it just started doing this out of nowhere and i've never had a problem like this before...Although i forgot to mention...one time i was driving about 60 on the highway and i put the pedal to the floor and the voltage actually dropped from 14 to 12 and it stayed at 12 the whole way home....Still sound like a regulator?

 

if it jumps higher than 14 i'd be worried. between 12-14 is ok. but if its 14 or above i'd suspect an issue.

 

Yea i know...I try not to be picky about the car but it's run perfectly at 14 volts for the past 4 years and now this happens...it just urks me...the Powermaster I have is a 1-wire design which goes right to the battery...I'm gonna have a new internal voltage regulator put in it and i'll let you guys know how it goes from there.