Yes, it is OK to leave AirPods charging overnight, over a week, or over a month.
The case will go into a trickle charge mode when full capacity is reached, which minimizes the number of charging cycles used while preserving the life of the battery.
Is it bad to overcharge your AirPods?
It is best to keep the AirPods in the case when you are not using them. They also do not overcharge. When your AirPods are out of the case they use battery even if you are not using them. To keep your AirPods charged, put them in the case when you’re not using them.
How long can you leave AirPods charging?
Your AirPods can get up to 5 hours of listening time3 or 3 hours of talk time on a single charge. If you charge your AirPods for 15 minutes in their case, you get up to 3 hours of listening time5 or up to 2 hours of talk time.
Should I charge my AirPods every night?
You don’t need to keep your iPhone or other devices from getting below 40 or 20 percent, you won’t hurt them if you run them down until the device powers itself off. You can charge it every night, even if only at 90%.