While returning from Rolling Thunder Sunday I pulled off to a rest stop and noticed the battery light on and the volt meter around 10 volts. Revving the engine did not turn off the battery light or significantly move the volt meter. I turned off my passing lights and continued to ride at 70 mph, the volt meter read just below 12 and the battery light stayed on. I rode this way for the next 300 miles, and kept it running while I got gas. I could not find an open Harley Dealer. I stopped for 6 hours at a motel and when I started the engine the battery light was off and the volt meter was pegged at 18. After 5 minutes riding the cruise dropped, speedometer and tach lights went out as well as all the indicator lights in those two gages. Thankfully I had a Garmin 660 and was able to tell my speed as I could not see the speedometer. When I slowed for fuel the lights came on and the volt meter read around 14 so I stopped the engine while fueling. The engine started normally and all gauges read properly. As I started down the on ramp the volt meter pegged and the speedometer and tach including their warning lights went out, cruise would not engage. This continued for several hundred miles until it became light. At one point when I could see my trip gauge I tried to reset the A to zero but it would not change. The volt meter remained pegged and would read correctly, the cruise would engage at lower speeds, below 45. As I neared home off the interstate cruising at 55 for an hour with several stop and goes, everything looked normal. After I arrived home I turned on the ignition with the engine not running and the volt meter read 12.