Bad Battery???

I'm sorry if this question is the same as the one previous mine, but I'm having a problem following that thread.
I had a new starter relay and wiring fixed this past weekend. 1973 Dart 318 wouldn't start, and I thought its was a bad alternator. Took alternator to Autozone and it tested good three times. Still having problems with charging.

So here's the issue, when the mechanic tested the alternator, it tested over 14 volts. When he tested the battery, it only tests out at 12.57 volts. Couldn't he make a test wire to go from alternator to battery + and if the battery starts to test at or more than 14 volts we know it has to be something from alternator to amp meter or from amp meter to battery?

Thanks in advance,

Jason