Update on Charging problems

I had posted on a loss of charging a -30. Well, I have not been able to get it checked out yet, but what I am noticing is the alternator will charge at about 7 volts when I start it up. It will continue to charge at that rate until it has been hit with some high RPM or some other shock. The colder it is, the greater the shock needs to be. When it finally switches, it jumps up to 15 volts and then settles back to 14-14.5.

Any ideas?