joystick charging

How are teams charging their V5 joysticks? Can we use a power bank? Or must we use a USB cable to our laptop or wall charger?

According to a Q&A it is legal to have a portable charger connected to your V5 controller during the matches. You can assume the rest :wink:
EDIT//: https://www.robotevents.com/VRC/2018-2019/QA/42

Thanks Connor.
Chuck