IF your voltage is being properly rectified, then your AC readings will be minimal.
If your voltage is NOT being properly rectified, your AC readings will be high. Many times, the entire diode rectifier doesn't fail. Instead, only one or two diodes fail and you get a large AC voltage out.
If your DC voltage is low, and never goes higher to indicate a charge, then the voltage regulator isn't providing the excitation to increase the voltage.
Many times, the rectifier causes damage to the regulator when it fails.