93 Ranger Charging system problem

[chollis]

My son changed his solenoid as it went bad last week. After installing the new one and driving for a day or two the battery went dead. He took the battery and alternator to the shop and had them tested. The battery tested out as good and the alternator tested as bad. He replaced the alternator with a new one. Two days later the truck dies again due to a dead battery. He takes the alternator off, goes back to the shop for another test on the new one and is told that it is bad, it voltage output was good but the diodes are bad. So, they test another new alternator before he leaves the shop, he installs it. The truck dies two days later. I suspected a wiring issue so today I pull the alternator and checked for continuity back to the battery. There was none..... long story short, I found a wire he didn't hook up when he installed the solenoid. I hooked that up thinking the problem should be solved but now after starting the engine the battery light comes on and the voltmeter zooms past 18 volts.

Could running the alternator without it being properly connecting the wiring thru the solenoid damage the alternator? I am really open to suggestions.