Even if the battery were going bad, it should run just fine if the bike's charging system is doing its job. I'm also getting a Datel, as I'm paranoid about stator and rectifier problems. Had a stator go out on a Ninja and without a meter there's no way to know it's a problem until too late. I think as soon as I noticed the voltage was dropping, I would unplug the headlights to help preserve the battery for the ignition circuits.
2014 V-Strom 1000 - Desert Khaki
2011 Burgman 400
2007 Honda Helix
2013 V-Strom 650 - sold