TheSamba.com :: View topic - Alternator Voltage Regulator...how to test?

Wed Sep 21, 2011 9:31 pm

hello forum...again :D ...ive recently opened a forum regarding electrical issues but im not getting answers as quick as id like on that forum so i started this one...

vehicle specs: 1981 air cooled vanagon non camper version standard transmission.

here goes... ive charged my brand new battery, cleaned the ground cable from the chassis to the tranny, and im only reading at 12.9 volts at the battery while the motor is running. The alternator is new, and was also tested...it passed. i was told that with the motor running, the volt meter should read approximately 13.5 volts or higher. this isnt happening.

1. i was told that the alternator is rated at 14 volts.

2. i do not know how to test the alternator while it is in the motor.

3. my google searches lead me to believe that the voltage regulator is a possible problem. the voltage regulator is external in my van so it should be easy to test however, i do not know how to do this.

if anyone has experienced this, or has some info as to how to tell if the regulator is bad or how to test the darn thing please feel free to let me know.

Wed Sep 21, 2011 9:42 pm

Go to the positive post on the alternator and measure voltage. If it is substantially higher than voltage at the battery, your voltage loss is somewhere in between (including grounds.) To really test the alternator, disconnect the charging wire and measure it while running. It should be 14 volts+. Don't do this too long or your battery will wear down.

I suggest replacing the alternator-starter cable, available as an upgrade from Vancafe.

But first, figure out what's wrong.

Wed Sep 21, 2011 9:56 pm

ok perfect...thats putting me closer to understanding how to do this...now all i have to do is figure out what wire does what and goes where... i dont even know how many wires are on the alternator :shock: