https://matrix.zimage.com/_matrix/media/v3/download/ross154.net/uWAvgOnkKrcScFUZUoAAmOlD/IMG_7370.JPG for a photo.

4S uses the original battery and mostly connected to a power connector. Rarely used these days.

2 6+s on their battery replacements (92% and 83%) from a local Apple store on 5/1/2018 due to the batterygate).

Do I need to worry about them? They both still work and used for basic usages.

Thank you for reading and hopefully answering soon.