Has anyone ever heard of a voltage drop as the engine gets warm?

On a cold start my turbo timer (no comments please. The previous owner installed it) shows 14.0V. Then it´ll begin to drop as the engine gets warm. I´ve seen as low as 12.9V even with a 1000RPM idle!

Measured the voltage on alternator terminals and it shows solid 14.4V. Couldn´t find a short.

 

Did you ever figure out the cause of the voltage drop?

 

Not yet. But my alternator was bad. I'm waiting for a new one. Should arrive by thursday.