Following are the ways to check airpod battery life on your iphone, ipad or ipod touch:
Open the lid of your Airpods case and hold it close to your ipad, iphone or ipod touch. Wait for a few seconds and the charging status of your airpods will be visible on the screen of your device.
You can also check the battery of your airpods with the widget of batteries present on ipad & iphone.
Also, the charging of the case only appears when one of the airpods is inside the case.