It should be no more than 14.2 volts. If it is than that is the reason
the battery is failing.

John, it is below that, I have a voltmeter on my dash.

I wouldn't trust an in-dash voltmeter to be that accurate.

ditto. if you haven't got 14.2 to 14.4 at a decent rpm, your charging
system has a problem. That would kill battery life.

Karl