Overcharging

[Barnsworth]

So my '92 3pg had trouble starting the other day, like the battery was just about flat so I charged it and it ran okay for a day or so then did the same thing.

I put the volt meter on the battery and it was showing around 14.7v, I started it up and it pulled it down to around 10v and then with it running at almost full throttle it went up to a little over 20v!

I thought that the green wire from the start/gen may be off but checked it and it was fine.

How (and why) can it be charging that much and the battery showing that may volts and still going flat? Did it fry the battery? The voltage regulator was new this past summer although I know that doesn't really mean anything with some of the junk a person buys.

Does anyone have any idea of what my issue could be?

All suggestions are appreciated! Thanks in advance.