One of the most useful accessories for 360 cameras is a USB power bank. There are many of them and it can be confusing to choose one that works well. I found one that has sufficient power, strong output, and is sufficiently compact.
It’s called Okzu and is about the size of a smartphone, and it’s slim enough to fit in the storage case I found for the XPhase. Note: The photo at the top of the article shows a different brand which has been discontinued, but has the same dimensions as the Okzu.
It’s a 10,000 mAh USB power bank with three ports (two USB Type A, one USB Type C), each with up to 3A (at 5V), which is strong enough to charge the XPhase while it is being used, and is even powerful enough to charge the Oculus Quest (reviewed here) while in use.
Note that to plug the XPhase into a USB power source, you’ll need to remove the bottom cover which has the 1/4-20 tripod hole. You’ll therefore need this clamp to hold the XPhase and attach it to a tripod.