Join Date: Mar 2013
Location: Los Angeles, C.A.
I Ride: 2012 ZX6R
This actually happened to me yesterday. I ran a quick errand, got home, hit kill switch, but left key in the On position.
I didn't time it, but I'd say it was left On for about 30mins or so. Keep in mind, bike was already running previously, so one head light was on. Anyway, after about 30mins headlight was on, but voltage had dropped enough to not start the bike.
Shit happens. Battery is a little over 2 years old.