I got an 18650 shield, which I got wired up and powered everything from there. But the LED displays are very dim and don't behave as expected, after a couple of button presses they reset or display odd values. I assume that this is a current problem?
I would expect a single 18650 to be able to supply enough current, the one I am using is rated for 24amps. The module is supposed to have a 1.5amp supply steady, with 3amp max at burst.
I have some dual 18650 battery holders that I will run through a buck converter to see if that makes a difference, but my confidence has been shot in the solution so far!