Thought I'd report back on my experience re-calibrating the Oasis1 battery.
Before re-calibrating, I was getting some odd readings where the cover battery suddenly plummets, though the readings for the Oasis seemed okay.
I ran the cover down to 1% (the lowest it would go and the point at which a low-battery warning would appear every time the Oasis was connected to the cover), then it took a bit more reading to run the Oasis battery all the way down. I ignored the low-battery warnings until the Oasis shut off by itself.
Then I connected the Oasis to the cover, plugged into a/c power and charged up to 100%.
After all that, I was alarmed to find the Oasis battery would go from a full charge to 30% in less than 2 hours!
I then let the Oasis battery run all the way down again until it shut itself off by itself. This happened after only 3 hours of reading!
Then I re-connected the Oasis to the cover and charged everything up to 100%.
Now everything is operating smoothly. I'm getting about 8 hours of reading on a full charge, the battery readings for both Oasis and cover are as expected (no more odd plummeting).
So if anyone is planning to re-calibrate, you might want to start with just running down the Oasis itself, not the cover. If that doesn't get you the desired results, then run down both, keeping in mind that you might have to re-calibrate the Oasis again afterward.