Summary:
About the Airpods:

I discovered the following (please follow my line of reasoning):

1) If the Airpods are paired to a single device (example: iPAD Pro 9.7, using last iOS version), or my PC (Windows 10-64 bit, using a dongle 4.0 Bluetooth),or the Apple TV 4;

2) This after a few full discharges;

3) The charger case from the Airpods without any defects. Meaning that if I let the Airpods INSIDE THE CASE (paired to a single device) and don't open it for 24 hours, there's no drain, the battery continues at 100%. This after both the case/Airpods were fully charged. So my unit is not one of the defective ones that had this issue.

If I reset the Airpods to factory settings, and pair them to the iPAD or PC;

And if I turn Bluetooth off in ALL MY DEVICES (and don't pair to Apple-TV 4, for this test);

The battery (this is where I am describing the issue for the bug reporter) is wasted COMPLETELY after less than 12 hours. Meaning it keeps trying to connect to previous devices, no matter what. I believe it wastes 4% each hour, or more.

This is a bug that needs to be fixed in a future firmware. I use the last one, 3.5.1. I noticed the Airpods keep trying to connect to the previous device used, even if I hit DISCONNECT in the device settings. They keep broadcasting the battery levels, even if inside my drawer, from a short distance.

Bottom line: since there's no ON/OFF switch, this must be a bug from these Airpods. The reason I need to let the Airpods outside the case is to be able to grab them quickly and put them back in my ears, at random moments of the day. This unnecessary waste (despite the fact the charger case is really useful/fast for a few minutes, if we need to recharge them) thwarts those plans.

To compare products, I also have the Apple Pencil.

The Pencil is paired to one iPAD. This iPAD Pro 9.7 never has Bluetooth disabled.

In 24 hours, even I don't use the Pencil for anything, the battery wastes a few %. Not 100 to 0% in a few hours. In other words, "constant monitoring" is "constant use" for the Airpods. This must be a bug, it can't be normal.

Steps to Reproduce:
Just fully charge the Airpods and case (or just the Airpods). Then pair them to a single device. And let the Airpods OUTSIDE the case. Monitor them for at least 12 hours. In 12 hours they are going to be fully depleted. Don't put them in your ears and don't use them AT ALL during this period. Use your own iPAD/device speakers, don't use the Airpods.

Expected Results:
See above.

Observed Results:
See above.

Version:
Airpods using last firmware, 3.5.1. iPAD Pro 9.7, last iOS.

Notes:
Please clarify this issue.

Configuration:
See above.