Folk, I drove my 1980 MGB for about 90 miles the other day and all of a sudden the car died. The battery was dead. I got a jump and got home. I charged the battery which was new. Then I tested it with my multimeter. 12.4; perfect. I purchased a new alternator and installed it. Then tested it and got 14.25 while running. Turned it off and she ready 12.4. Again, all as it should be. then I drove to the gas station and back (5miles total) and checked my reading whilst running and it read 12.18. You can imagine my concern. Turned the car off and now she reads 12.27. I am starting to kill the battery again. Took the alternator off and took it to the local parts store, had it tested and the said it test good; its charging. So then I checked all connections, battery cables, ground, belt is tight, not slipping etc. In fact I changed all four fuses for new fresh ones and also changed the Voltage Stabilizer which is mounted on the fire wall above the steering column. Still the same readings.
Has any body had this before? I have not owned the car long so I don't have a long history with this car and frankly I suspect the car was doing this the entire time, because that 90 mile ride was the longest ride I ever took.
Folk, any ideas or what I should consider next?