Coldpower is a no go with SeedSigner -- not enough power to drive all of the components, camera activation will commonly cause a software crash. The usb port closest to the thumbstick is hard wired for power only, so if you use that port, "offline" power isn't really necessary.
Discussion
Seems like there’s a market opportunity for a ColdPower alternative with higher output.
Maybe one of those phone recharger external batteries?
Just about any usb power bank will work great. 🙂
There’s also these https://www.amazon.com/PortaPow-3rd-Data-Blocker-Pack/dp/B00T0DW3F8
Thank you for letting me know. I’ll look for an alternative power source