Charging system test
Race Director
Joined: Sep 2001
Posts: 10,560
Likes: 439
From: Wellington, FL
St. Jude Donor '11 thru '25
By attaching the volt meter to your battery, red to the positive and black to the negative, the output or volts with the engine running should be between 13.5 and 14.5 or so. This test pertains only to system output and other problems such as bad alternator diodes and battery drains must be checked in other ways. 
Racer
Joined: Dec 2007
Posts: 374
Likes: 12
From: PHILADELPHIA PA
voltmeter will only allow you to read system voltage. about 14.3 vdc @ 2000 rpm depending on batt condition. will need ammeter to read system amperage coming from alt. check manual for full field testing.
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
That meter will tell you just about everything you nee to know.
As stated above, test the voltage at the battery AND at the alternator.
They Should be virtually the same, but there might be a Small amount of voltage difference between the two, less than .2v
Set the meter to DC Volts, ground the black lead and put the red one to the the stud on the back of the alternator. With RPMs above idle you should read 14.xx volts. Same test at the battery, same reading.
Engine off, key off, same tests should get 12.xx.
Are you having battery problems? If so let me know and I'll walk you thru troubleshooting.
As stated above, test the voltage at the battery AND at the alternator.
They Should be virtually the same, but there might be a Small amount of voltage difference between the two, less than .2v
Set the meter to DC Volts, ground the black lead and put the red one to the the stud on the back of the alternator. With RPMs above idle you should read 14.xx volts. Same test at the battery, same reading.
Engine off, key off, same tests should get 12.xx.
Are you having battery problems? If so let me know and I'll walk you thru troubleshooting.
