[McRider]

I worried about this myself a year or so ago when I added heated grips while also using a Synergy heated vest. It's not too hard to find the output of the alternator, and although I don't remember the exact number I believe it is around 350 watts, which seems plenty adequate. The problem, though, is it's hard to know how much power is used in normal running of the bike due to the headlight, taillight, fuel pump, ECU, etc. But, the bottom line is that I have been running the vest and grips with no problems.

 

[McRider]

Well, you shouldn't have your high beam on if you're stuck in traffic. In fact, without the high beam and brake light you've gained near 100 watts, and that's sort of the normal running mode.