Mobile no battery backup
My headset mobile battery health down down more complicated no help please imdetliy actions
If you are laking about Battery Health in your mobile phone (Settings, Battery, Battery health) then it will gradually reduce at the rate of 1% drop every 4-8 weeks. If that is the case (eg 6 month old phone has 94% health) then that is normal. No action required.
If it drops below 80% in the first year then contact the Apple Store under warranty.