I'll bet Apple is going to update these to not include the battery percentage anymore.
Anyways, I've gone 15-20 hours with my pair of AirPods and case fully charged without any noticeable case drain. But if I look over a period of days, not hours, it's clear the AirPods themselves are draining about 3-4% per hour on average while just sitting in the case. That results in a case drain of up to 20% per day.
If I add up the actual use of the AirPods and the standby time, it's fairly consistent over a period of days (don't bother trying to see what happens after an hour or two - it isn't a long enough period of time to be accurate). I go periods of many hours where it looks like the case drain isn't happening - but I think it is. It's simply the battery meter isn't all that accurate, especially when at a full charge. You really have to sort of add up what you get from use and standby over a full charge cycle to know if there is a problem or not. Even though my case and AirPods can appear no to drain overnight, I'm pretty sure they are and the battery meter will catch up over the next few days.
Apple would have been better to say the usage is:
AirPods with Charging Case: more then 24 hours listening time, up to 11 hour talk time, or up to 5 days standby.
AirPods (single charge): up to 5 hours of listening time, up to 2 hours of talk time, or up to 1 day standby.
Instead of:
AirPods with Charging Case: more than 24 hours of listening time,(3) up to 11 hours of talk time(6)
AirPods (single charge): up to 5 hours of listening time,(2) Up to 2 hours of talk time(5)
The way they say they tested to come up with the "24 hours listening time" completely ignores standby time, which is significant for a device like this that has sensors always on:
Testing consisted of full AirPods battery discharge while playing audio until the first AirPod stopped playback. The drained AirPods were charged for 30 minutes, then audio playback was continued until the first AirPod stopped playback. This cycle was repeated until both the AirPods and the Charging Case were fully discharged.
They include standby time in iPhones, and it seems like it would be even more important to include in this product.
My expectation was that I'd be able to use these for an hour or two each day, and just charge them once every 2 weeks or so. The way they presented battery life claims and the way they tested was very misleading.
I think it's still a great product, fun to use, and charging every 2-3 days isn't that big a deal. But they really mislead people and are probably going to have a lot of returns/exchanges that aren't really necessary with people thinking their battery life is shot.