So I have three Photons with identical system firmware, identical application software, identical USB/Battery-based power supplies, all using identical batteries. One of these Photons consistently drains the battery much quicker than the other two (1 day vs. 30 days).
Though trial and error I have been able to rule out the batteries, as well as the power supplies as being the issue. The problem seems to follow this one particular Photon itself. I suspect and am willing to accept that its a one-off hardware error on the device but I just thought I’d share this situation in case anyone had comments.
Here is one further piece of information: by coincidence I was able to witness the problem-Photon reaching the end of it’s battery’s life. It was pulsing white; the frequency of the pulse seemed to decrease until it was finally lights out. At that point I plugged in the USB supply, the Photon powered up and behaved normally. Once I disconnected USB power, it again reverted to the white pulse after a few minutes. before going dark.
From what I understand, the Photon pulses white when it is reset so I suspect this white pulsing was simply a symptom of the battery being low, resulting in multiple resets before it died. In other words I think this white pulse was just a symptom of the main issue.