[strictlypersonl]

The voltage regulator should keep the peak voltage below about 14.8V. More than 17V will cook the battery pretty quickly, but I doubt that's already happened. (I hope.) Charge the battery again and disconnect the plug at the voltage regulator. See whether the battery holds a charge overnight. If it does, check the wiring from the regulator to the alternator. If that's OK, replace the regulator.

!!! If you have a dash charge-warning light, check that the wire from the regulator to it is not grounding out somewhere. !!!

And put a fuse in the regulator power circuit, making sure that the power goes off with the key.