Odd AMP Gauge behavior

In the morning, during my 4 mile commute in light traffic, the amp gauge shows negative charge at around 11 volts. Yet, it starts in the evening, driving after dark with headlights on, the gauge shows 13 volts.

Ground issue perhaps. Morning – colder = higher resistance somewhere in the circuit.

Hmmm, will check again, but everything looks clean.

I assume this is the volt gauge (not amp gauge).

11 Volts with engine running suggests alternator not performing well, or weak. This is likely worn brushes but could be other things.

The thing to do is to measure the battery voltage with the engine running and head lights on. If it won’t pick up to 14.5V or thereabouts, you have a suspect alternator. Usually quite simple to fix.

It could be belt slipping, but this will likely be indicated by squeal under load.