Give me an idea what's blowing out the electrical system on my 1999 Ford Windstar?

Two new batteries, two new alternators, two new serpentine belts in the past two years. Most recently a new battery (last one was only less than halfway through its warranty) a new alternator, and a new belt with tension pulley on July 20, 2015 - two months ago. Check charging system light started coming on a few times starting about 5 days ago. Then another lost day of work today. Anybody got a clue? I'd really appreciate any help.

Take it to the dealer. I pretty sure the computer runs the alternator on your vehicle. There may be mechanic TSB reports for your problem and by now you need all the help you can get. The grounds to the alternator need to be tested and after market alternators may be causing more problems as I've seen many bad right out of the box.

I'll bet you have BAD GROUNDS. All grounds need to be Clean and Tight or strange things can happen.