I am wondering if anybody has experience with using a portable powerpack to power the teensy 3. I recently purchased a Portable powerpack made by Verbatim, it works to turn the teensy on, however after about 10 minutes it stops sending power. I am not sure why it does this, maybe it is looking for some sort of signal from a device like a cell phone, that indicates it is actually charging. So, if anybody has another device that they have used in the past and works that would be great. I need something people can wear while walking around, so can't be too bulky, and only needs to last 8-10 hours at most. Thought this would be any easy solution since already has a usb port and not bulky. Thanks for your time and any suggestions are appreciated.