My DRZ recently died due to a weak battery DURING a night ride.
I hadn’t ridden it for almsot a month (due to travel and stuff). The bike started a bit hesitantly but then it ran fine. About three miles down the road, I got stuck at a traffic light for a couple of minutes, because the police had blocked off the road due to an accident. When I finally got clear, I made it to the next light, and as I slow down and signaled to turn, the bike died. It woudn’t restart, and the cranking got weaker quickly. My wife came by and gave me a jump from the car battery, and the bike started right up. I rode it home in heavy rain just fine. The bike sat for another 2 weeks, and yesterday I rode it to work and back home (39 miles total) ok.
I think what happened was I started with a weak battery (from sitting for nearly a month), didn’t go far, and then idling at the light, with the brake light on, drained the battery below the level to keep the bike running.