I bought a pack of "Deleepow" batteries similar to these. I tried them in a Dremel tool, and right off the batt (pun intended) one failed, internally shorted the protection circuit, and self-discharged with plenty of heat released. It would never charge again. Too fragile for me.
Does the adapter have a USB connection? If so, that's probably what's doing it.
Also, I've had perfectly good 20V batteries show up as bad when the thermistor goes bad. It's a little black thing, supposed to be around 8 k ohms at room temperature, if not the pack will not charge and shows up as bad. I have a few of them from past failures.
Hey, good job by Nikon. I have Nikon equipment through a back door, i.e. a Kodak DCS Pro 14nx in my Kodak collection, but if I ever wound up with FF equipment it would be Nikon mirrorless. Too bad they didn't include a Z adapter for free with their new cameras...
I have one of the cheap ones. It's reasonably accurate. I marked the spot that the detector tube faces for better readings on objects such as Super Takumar lenses, orange neon pilot light bulbs, and smoke detectors.
Somewhere on my computer I have a photo of a plane with the license N3EG after a crash. No connection to me and I am not a pilot. I specialize in crashing flight simulators only. I'm just a ham radio operator and photographer.
It was 1981, and I was moving from Philadelphia to Los Angeles. I had just met my future wife, and was doubling my salary with the move. I bought a Pentax Auto 110, since I was into smaller things. This was where I got my start with the four thirds format as film, and I still shoot micro four thirds 41 years later with some of those original lenses.
I've wondered about some people for a while. There's a certain color called "shadow bronze" that I always say is green - nothing bronze about it. Motorola radios used to use that color.