The charging problem was my mistake. The battery had a transparent plastic covering that I hadn’t noticed. Once I removed it, the charger worked fine, glowing red while charging and green with fully charged. Once charged, it works fine. I’d say it’s slightly brighter than my Princeton Tec Impact XL (4 AA), and much brighter then the Streamlight 4AA I keep in the car. This 18650 “zoomie” light will replace that for my car light.
However, it’s not nearly as bright as a friend’s larger “zoomie” with a 26650 battery.