There is no separate AC charger. No information is provided concerning the need for a separate charger. There is no information concerning charging via computer.
The AC Adaptor plus into AC source. In my case it is a wall unit. The adaptor has no fixed wire. The USB cable plugs into one side of the USB port on the AC Adaptor. The other end of the cable plugs into a device with a micro port.
The Nikon and two of my cell phones have the same port. In each case I see a green light if -- and only if -- there is a proper connection between the AC source and the unit.
I would never dream of using a camera while it is tethered to a charging unit. It may come to pass that a freshly charged Li.ion battery is a better choice.
Mac: No windows, No Gates, Apple inside