OK, so I had a real bad day yesterday due to a pulled muscle in my neck, sending shooting pain into my left ear! Nothing like the feeling of a pencil being shoved down your ear canal to to ruin your afternoon. My doctor prescribed muscle relaxers and I obeyed. I took one shortly before bed and don't actually remember putting my head down. Long story short, I never plugged my phone in to charge.
This morning the phone was dead as a door nail, not responding to the power button, so I plugged in the charger and in about 15 seconds the animated battery appeared, but instead of it saying 0%, it started at 5%. This confirms (at least to me) what I've been saying all along.
Have you ever had batteries in something like in a flashlight and watched them die, for instance? Have you then powered off and on again only to have it come on bright for a brief moment and then go dim quickly? How about sitting it down for a while and coming back to find it's bright again, and for longer than before, but eventually dies again? This is the battery slowly finding increased voltage while at rest, because while being used the current being pulled was so strong it pulled the voltage of the battery down. Once relieved of the loud sucking sound the battery starts regenerating voltages. This is a common phenomenon.
The point...if I had actually drained the battery to 0%, and had done so with a battery meter that wasn't calibrated properly (by charging with power off to 100% and avoiding letting it drop much below 15% before charging again), I might have had a BSOD, boot looping or any of a number of other low-battery related issues. Instead once the phone powered down at 0% (as was read by the phone's battery meter), the battery actually started rejuvinating slightly so that once I plugged it in, the voltages were higher and as a result the meter sees the battery at 5%, not 0% or worse.
Anyone care to debate?