You need to make sure that a genuine Apple battery is installed in your phone, but Apple or an authorized Apple Service shop will not sell the part to you unless they also install the battery in the phone.
If you or a non-authorized shop install a "knock off" battery, the Battery Health feature will not operate correctly and the phone will display a message that it does not recognize the battery that was installed.
Expect to pay about $50-70 for the battery installation service depending on how old your phone might be.
