Battery not charging - tell me what I'm missing

[doodah man]

Ok, this will be a long story. If you're not into long rambling stories, skip to the bottom for a concise summary.

We left Philadelphia on Friday on our way to Tichonderoga, NY for a friend's wedding party. There was a crazy thunderstorm about 60 miles south of Albany that lasted about 10 miles. We were running the AC/defrost, wipers, headlights and flashers. We just made it to Albany when the truck started to miss and sputter. I babied it to the nearest exit and it died at the first stop light. The battery was completely dead. We have AAA+ so we had 100 miles free towing and our destination was 97 miles away. Figuring it would be easier to work on there in the morning, we rode the rollback the rest of the way to the wedding. The next morning I pulled the battery and alternator and took them to a Napa for testing. Battery drained but OK, alternator "possibly" bad (the guy there wasn't sure he hooked it up right. Yeah, I know, "What?"). They didn't have a replacement anyway, so I took it over to Advance Auto. I had them test it again on their machine. It came up good (putting out 14.4 V) twice in a row. So I charged the battery and put everything back together. It started right up and ran fine on a 30 mile test drive. So we enjoyed the rest of the party and headed out Sunday morning for another friend's house in Chatham NY (~100 miles away) and had no problems on the way including a few stops and starts. Monday morning we got an early start for Philly, but stopped at a gas station in Chatham for coffee. When we tried to start it again the battery was drained. We got a jump and made it back to our friends house. I borrowed a car and picked up a new battery (the original one was 8.5 years old) and a volt meter. The battery read 12.6V when I installed it. At idle, the voltage at the battery posts was 12.3V and the voltage at the battery terminal on the alternator was 12.3V. I was expecting something like 14 V. I was able to track down an alternator locally and installed it in the parking lot of Chatham Auto Parts (That place was an old school independent parts house. Awesome.). The guy at the parts store had a tester that showed no voltage change with the new alternator (still about 12.3V). So I put the old one back on and drove 15 miles to Hudson to get a new voltage regulator. I put that on (used the old condenser) and still no change in the voltage at the battery. Drove the 240 miles back to Philly without turning off the motor. The battery was 12.0 V when I parked in Philly.

The only other thing I noticed is that it seems to be running a little colder than usual (maybe 10% or so). I figure that is unrelated and maybe just a thermostat that needs replaced. Also, the alternator belt did break about a month ago.

Now I'm lost. I never tried cleaning contacts on the alternator plug. Will try that after work today.

Here's the summary of what happened and what I've tried to fix it:

1. Truck died after about 250 miles of driving including one soaking T-storm that required heavy use of accessories. Truck would not crank and accessories barely worked. Battery was drained.

2. Battery tested ok, alternator tested Ok: putting out 14.4 V.

3. Charged battery, reinstalled alternator and drove ~120 miles with at least 6 or 7 stops and starts without incident. The only weird thing was that the engine temperature was consistently lower than before by about 10%. After several normal starts the battery was drained again and required a jump start.

4. Picked up new battery (12.6 V off the shelf) and 12.3 V at battery and alternator battery terminal with the engine at idle. I expect 14 V.

5. Installed new alternator. Still 12.3 V at idle.

6. Put old alternator back in and replaced the external voltage regulator. Still no change. 12.3 V at idle.

7. Drove 240 miles back home without shutting off the engine. Battery at the end of the trip measured 12.0 V with engine off.

Any suggestions for other diagnostics or ideas why this thing won't charge?

Thanks in advance.