This is kind of ridiculous.
I've been liking my Serfas True 500 bike light. It's one of the new generation of bicycle lights - compact, LiOn, charges from a mini-USB cable and power supply, and brighter than you can believe. These lights are a generation after the Ixon IQ that we were excited about in 2008.
Even if you're not a bicyclist you've seen these; in blinkie mode they are impossible to miss. In fact blinkie mode is so conspicuous its almost rude; I only use it in dim daylight.
These lights are amazing. Sometimes progress happens. It costs less than a replacement NiMH battery for my $350+ NiteRider gear of the 1990s, is brighter, 1/10th the weight, 1/10th the size and so on.
On the other hand, these are techie things. So progress is imperfect.
Coming home in the dark on a blustery sub-freezing night my Serfas was totally dead. Nothing - despite charging off my laptop just minutes before. Not good. Fortunately I use a Blackburn Voyager Click light as a sidelight (I go with one forward light, two lateral very bright white blinkies, and 1-2 posterior red LEDs and reflector), I made that an emergency front light. Aside from almost running over an off-leash wee doggie who dashed in front of me I made it home fine.
At home I plugged in the Serfas. Nothing happened. Not a blink.
Then, for lack of anything else to try, I pulled the battery. Looked fine, so I put it in. The light worked. It was fully charged.
So what happened?
Well, maybe the battery compartment wasn't quite closed. It seemed closed, but maybe it was a bit off. Or maybe this light has an embedded OS and I rebooted it when I pulled the battery. Could be either, but I like the second. This is one weird world we live in.
PS. The current generation of ultra-light and compact USB LiOn bicycle lights are amazing utility flashlights.
Update 5/1/12: This time it started turning itself off. It came right on when I pressed the power switch. I discovered tapping it on a hard surface would turn it off. Not an obvious bulb problem though; once it was off tapping didn't make it flicker and a power button turned it on again. I pulled the battery and again it seemed better. A bad battery sensor? If this is a widespread bug the Serfas True 500 deserves a recall.