When I turn on a significant electrical load (AC, headlamps, windshield wipers, radio etc) and travel slowly, you know, rush hour traffic, the voltage gauge will sometimes read around 11 volts. The ammeter I installed continues to read on the + side regardless of what the voltage gauge is doing so I assume the alternator is putting out enough current to drive the load. Lights are full bright (no dimming), the heater/AC fan runs at a constant speed whatever the engine speed may be. The alternator is about 3 years old, battery is about 4 years old and nothing bad seems to be happening. I am just trying to understand what's going on. All input cheerfully accepted.