If you have a constant red light, there is definitely a problem in the charging system. I ran into this in my airhead's charging system years ago. Sounds like brush problems to me. If you can solder, they solder on fairly easily.
Running two electric garments is death to these bike's electrical systems. They are barley adequate to keep the battery charged and light the lights. Yes, they can run a vest, but that really puts the rubber to the road if there is any flakiness in the system.
Motoelectrik sells more powerful alternator for the airhead series, along with all of the ancillaries it requires. I believe that this increases the output from something like 40 amps from he stoker 20 amps.
Some people claim that when BMW increased the ampereage of the alternator form the /5 series to the /6 series, the engines made less power. I cannot testify to this as truth.
For the love of Baldy, would someone please buy my bikes?
For the next several days I will be telling a true abdenture from my own life. It seems harrowing, and will involve a sighting of Richard Gere, but I want to share this for many reasons.