Originally Posted by DaBigBR
I believe that light would use a NiMh battery, in which case it would be better to cycle it as completely as possible and definitely avoid leaving it on the charger for long stretches
What he said
I have used an ultra stinger for the past couple years and while I love the power and size, I don't really care for the battery life. I have found it necessary to completely deplete the battery at least once a week and recharge it from zero to avoid the battery memory issues.
Also, streamlight says that you can keep the light in the charger indefinitely and thanks to their on board circuitry, it won't affect the battery life or performance. That's true to a point, I've found it better to use the light till its dead before I plug it back in for an extended period. I just rotate my spare battery and I always seem to have enough juice to get through the day.
That being said, there have been times when I've had to transition to a back up light because the ultra just runs out of juice. It hasn't been very often though, and overall, I really like the ultrastinger.