How to diagnose AirPods battery issue?
Here is a method to determine if the frequent and/or intermittent disconnection of bluetooth, audio or microphone is caused by deteriorated batteries
Keep your AirPods buds in the charging case with lid open
Disable Automatic Ear Detection as shown in the screen below. The Toggle Switch should be greyed out to indicate that it has been disabled
Keep the lid open and the AirPods inside the charging case (do not remove the AirPods from the charging case). Make a phone call or play music or record using voice recorder app and determine if disconnection continues to happen.
You may need to turn up the volume and place it near your ear but keeping the AirPods in the case at all times during the diagnosis. If disconnection does not happen, this means that deteriorated batteries are the likely causes of issues and your AirPods are suitable for battery replacement
How does the test work?
The rationale for this test is to determine if the issue occurs when the AirPods are powered by the charging case. When the AirPods are in the charging case, it is no longer powered by the internal AirPods battery but by the charging case. Hence, if none of your AirPods issues occur, then it's likely an issue with the AirPods battery