This was more of an observation than an issue but @siliconlabs suggested posting it here.
When running a Thunderboard Sense from a Primo Power Bank the battery box shutdown shortly after boot. We are guessing it was detecting a very low current draw. The same board worked fine from a mains USB or from a coin cell.
Interesting observation! Unfortunately that makes the battery box poorly suited to powering an unattended Thunderboard.
Thanks for posting,