"At the battery" is EXACTLY where you should be measuring it.
You are not "under" charging, your system is not charging at all
For a really quick check, pull both field connections (the push on connectors) off at the alternator
Disconnect the connector at the regulator
Turn the key to "run", engine off.
Identify the blue field wire at the alternator, and check the voltage of that wire to ground. Should be very close to battery
Hook the blue wire back up to the alternator field (does not matter which one) and take your meter and measure from the SECOND alternator field terminal to ground. Again, you should have very close to battery
Take a clip lead and hook this exposed alternator terminal to ground. With the key in "run" you should get a small spark as you hook it up
Start the car and gently bring up the RPM, watching your voltmeter on the battery. The voltage should start to climb, do NOT let the voltage get above 15 if you can, and in NO case allow it above 16
IF this the voltage does not climb, either you have a problem in the alternator, or the charging lead / ammeter circuit has a problem
IF no change (still low volts at battery) move your voltmeter to the big output stud on the alternator. If the voltage is low here, the alternator has a problem
If the voltage is high here (much much above 14V) and low at the battery, you have a break in the charging line , the bulkhead connector, or the ammeter circuit.
If the voltage in the test above DID go up at the battery, you have a problem in the regulator or regulator circuit
Now hook the green field wire (the one unhooked) back up to the other field connector. Identify the green wire up at the regulator and hook this to ground with a clip lead
Once again, more RPM should result in increased voltage. If so, the green wire is OK.
With the key on or the engine running, confirm that you have "battery" at the blue wire to the regulator. IF so, and the above checks were OK, replace the regulator.
rayer:
