Overcharging Problems?

my 72 dart was fine, then started charging 16 to 18 volts with the engine revved up. I thought I checked all of my wiring and it appeared to be fine. The next day i started it and still had the same problem. I shut it off, tried to restart and nothing. Got looking things over again, and the negative battery terminal wire was loose. I tightened it and it broke. I replaced the wire end, cleaned the battery post, put it back on and it's charging properly. Sometimes the most simple and obvious reasons are the ones we miss....