TimmyT, that's almost a sure sign that the battery won't take a charge any more. When a rechargeable battery is in this state, it reaches full voltage after very brief charging. That's why you get the "charged" indication. It's a voltmeter, though, and it doesn't tell you how many watt-hours are in the battery. As you now know, you have pretty much zero.

A 2-watt tail light? Is a progressively increasing amount of overkill always a good idea? Jeez, my Cygolite Hotshot is pretty darned bright, maybe too bright. Do we really need something better?