On my buddies 2000 502 the voltage is around 12.3, and when he turns on the Capt's call it drops down to 10.5-11.0 depending on rpm. If he turns the lights on it drops another .5
or so. Another issue that may be related, is the rpm will be fine and then drop off 400-500 and the engine feels like it's bogging down. I was wondering if a bad alternator could cause this because it's not putting out enough juice for the ignition. The engine will do this even if Capt's call is on or not. Does he have 2 seperate problems of could the alternator be the culprit? Thanks.

Seems the voltage should be higher than that running. Mines about 14.2-14.7
I'd look at that alternator

Yeah, that's what I'm thinking. I am curious if that could cause the drop in rpm. Maybe not enough juice to fire the ignition.

Check the voltage at the batteries. Do a load check using a battery tester before and after the battery switch. Battery switch can go bad causing a voltage drop.

It is definitely an alternator or wiring problem. Check the alternator ground and output at the alternator. It will tell the story. Low voltage will cause the engine to start acting squirrely. The biggest danger is that the fuel pump isn't putting out enough and you will wind up in a lean condition.

Rene

Don't replace the alt. yet. Where are you getting these reading form? Need to take a good volt meter and check what voltage the battery is putting out. A fully charged battery will be 12.7 volts. I have see different VM' give all kinds of reading. Now start engine & rev engine up pass 1500rpm. (some alt's need a lot of rpm before they start working) Check and see what the voltage is at the battery. Voltage should be 13.8 or somewhere close to that. I have seen dash vm's all over the place.