Charging System Question on a 90 D250

[PGunther]

Please forgive me as I am posting under my friends logon, but we are having some problems with the charging system on the above truck.

Here is the scenario...a while back I was driving said truck and I noticed I was loosing power on the gauges...when I noticed it was probablly around 11 volts. By the time I got it home, I had nothing...it had totally drained the battery.

After making some quick checks I don't see anything out of the ordinary. So the first thing I do is charge the battery and throw the battery tester on it. It immediatly pointed at the charging system.

So I start off by checking connections, cleaning posts on battery, checking the grounds and cleaning other connections. Still nothing.

Next I put a new reman alternator on it and still the same results. Tester still says there is a charging system failure. I am only getting charging volts off the alternator at where the battery is charged to at the time. Say the battery is at 12 volts when not running, I get the same off of the alternator once is started. If the batter is running dead and is at 11, then the charging volts is 11. Running the truck turns into running the battery down without the alternator recharging the system.

My next stop...voltage regulator. I find another used regulator around the shop and the resistance on the 2 regulators are different. So I swap the regulator hoping that I fixed the problem. Battery tester says good to go. Charging volts where it should be. I am getting 14+ volts from the alternator. Drive it for a couple of days with no change. Still get 14+ volts. I drive it today and it starts slowly falling. When I got back to the shop, I am only reading 12.3 volts off the alternator that read 14+ the other day.

Does anybody have any kind of idea what may be going on? Is there a way to test the voltage regulators? Should I just order a new regulator? I traced as many wires as I could before seeing cross eyed and I don't see any freyed wires or anything.

Anybody's help is greatly appreciated.

Mitch