When doing the engine run-up and pulling either engine to idle, the respective alternator warning light comes on as expected, but the alternator load in the a-meter doesn't chage at all and remains evenly distributed between the two alternators. It should, however, drop on the low idling engine (showing the warning light) drop to 0 (and rise on the other side), as the RPM is now too low. At least that's what all the Bonanzas did, that I flew, admittedly only on one engine and without another alternator to take over the load.

BR,

Markus