Do you have a link to what you mean? If you can make contact with the 2 pins on the back with 5v in the correct polarity (see https://www.espruino.com/Bangle.js+Technical#charging-pins) then it'll charge and you'll be fine. Anything would do...
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Do you have a link to what you mean? If you can make contact with the 2 pins on the back with 5v in the correct polarity (see https://www.espruino.com/Bangle.js+Technical#charging-pins) then it'll charge and you'll be fine. Anything would do...