Then one day it was dead (not atypical given my usage pattern), so I plugged it in. When I returned to it, expecting maybe a 10-15% battery level drop, it was dead again. Since then I've been charging it repeatedly but when I go to use it, it's again dead. Unfortunately, Fire O/S doesn't have any battery usage stats in it natively, and I just haven't taken the time to find an Amazon app that does, if there even is one.
Today I jumped onto my Pi-Hole (anti-ad DNS appliance) administration console and noticed a few very interesting things in the stats. First, of my first 5 "Top Clients", one is abnormally high in comparison:
That .124 address is the Fire tablet. Hmmm.
Then there are the "Top Blocked Domains". Again, a suspiciously high outlier:
Those numbers are pretty darn close, so the evidence is rather convincing that the tablet is attempting to report device metrics but failing and repeatedly retrying, killing the battery.
I haven't solved the issue yet. Part of the reason I set up the Pi-Hole in the first place was to improve the under powered performance of the Fire tablet so I don't want to just exclude it from using the Pi-Hole. I will likely just whitelist the offending domain and see what happens.