You should be at least 13 volts charging minimum, 14.7 maximum
Go to voltage regulator first for diagnosis, dianne has a good test procedure here on the forum i beleive;
Charge the battery first on low amps and test battery with a load tester,
If you dont have one, a fully charged, healthy battery will read 12.5 volts, if it reads 12 volts, it is not fully charged or will not hold.
There is a chart for testing the voltage regulator in the clymers manual, we should all own one of them. Let us know.