A:Answer Hi J,
Thanks for your inquiry about the WH1000XM4 headphones. Using a USB charger with an output current of less than 1.5 A would work. However, the charging time will increase, and the music playback time after 10 minutes of charging will decrease. A USB AC adaptor capable of supplying an output current of 1.5 A or more is recommended for optimum performance. You can refer to this link for more information:
https://helpguide.sony.net/mdr/wh1000xm4/v1/en/contents/TP0002752803.html
~Ralph