Gary, If you were able to turn the cable on the terminal, it wasn't tight enough. Brand new or recently cleaned and that loose, you could get by with. It is amazing how some battery connections can look perfect, but are not. The only way to be sure of a good connection is to clean both surfaces and tighten securely.

The only other thing in the back of my mind is a bad internal battery connection. Sometimes just touching the post will correct the problem for a period of time. But since you had plenty volts, you probably found the problem.

James