charging issues

hello everyone! first post here! so glad i found this site because im stumped!

so i was out riding this past weekend with a bunch of friends, and left my hardwired gps on between rides. the battery seemed to be doing fine, but one time, after starting it with the easy button, i was driving, and all of a sudden my headlights dimmed. when i eventually came to a stop and put it in neutral, i noticed the following:

1. when i rev the engine, both the stock headlights, and the neutral light dim. but when i let it idle, and almost die, they get real bright.

2. i have a pair of headlights mounted to my handlebars which are directly wired to the battery(inline fuse). these do not dim or brighten regardless of the rev's.

3. at the battery i show 12.8 volts when off, as well as when on.

4. when it is off, the neutral light and stock headlights do not turn on.

5. when it is off, the direct wired headlights turn on and are as bright as ever.

i have a clymer manual on the way but i was hoping you guys would be able to suggest if its the stator, rectifier, battery, etc, or tell me some tests that i could do to find out for myself.

i really appreciate any help i can get from you guys, and hopefully i posted this in the correct place!

thanks!
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