'99 E-300 "Battery Charge" warning at cold start-up?

This problem began Sunday morning over in Las Vegas, so we stayed over an extra day and had it checked at Fletcher Jones MBZ there on Monday. Of course, the technician couldn't see it happening because by the time I had driven it the several miles to the agency, the trouble had cleared out, and of course, they could find no indications that there had been a problem, and no codes had been set. They did find a supposedly loose battery connection for which I guess I got off lucky. They only charged me $53.09!
I thought the problem was corrected, but the following morning it did it again, and again on Tuesday and again this morning.

When this happens, the altenator tries to pick up the load, and it litterly makes the engine shake as there seems to be that much drag on the belt. But it won't stay charging, and the light comes on again. After the temperature gauge is up to normal and the motor is turned off just once and it is restarted, everything is fine with no malfunctions for the remainder of that day.
Only when it cools down as in overnight, does the problem return.

I have an appointment with the local Fletcher Jones in Newport Beach CA on Friday, and they'll keep it overnight if necessary. Hope they can locate and correct the problem.

I hope that the problem is not some relay having to do with the glow plug system, as the late 606962s are rather scarce in these parts, and the tech might never have laid eyes on one.
Kind of hard for them when they have had no experience with this problem locally.

Anyone hear of or had this happen to them?