Airpods battery level disappears after 15 seconds of connecting.

Hello iftekhar-alam.

Thank you for using Apple Support Communities. It sounds like you're experiencing issues not being able to see your charge status when using your AirPods. Allow us to investigate this issue and assist in any way we can.

Currently, there are multiple ways to check your charge status for your AirPods. We'd like to share a helpful resource with you. Please check out the link below:

Charge your AirPods and learn about battery life - Apple Support

Please review the section under "Check the charge status". You'll see that you can use the Batteries widget to view your charge status and also follow these steps "open your case lid with your AirPods inside and hold your case close to your device. Wait a few seconds to see the charge status of your AirPods with charging case.".

We hope this information is useful. Cheers.