Mmm.. between 50% and 75% depending on discharge rate, quality, and chemistry, but yes, a lot less than 100Ah.
USB Adapter Compatible with Dewalt 10.8V/14.4V/18V Lithium Ion Battery Packs YEX-BUR Cordless USB Charger Power Source Portable Converter Charging Adapter for USB Mobile Devices https://amzn.eu/d/3dSlfqvHave you got a link to it?
Have you got a link to it?