Battery capacity drop

Batteries are consumables; they lose a little capacity every time they are discharged, then recharged. On average this works out to about a 1% loss for every 25 “full charge cycles”. As one example, if you charge the phone overnight, every night (and that is what you should do; it is a best practice), it starts the day at 100%. If it drops to 20% by the end of the day before you charge it again overnight that counts as 0.8 full charge cycles (20% to 100%), or about 24 full charge cycles per month of use. For this example your battery capacity will lose about 1% per month. Of course, if the end-of-day level is higher than 20% the capacity loss will be a little less, and if it is lower than 20%, or you charge it during the day, the capacity loss will be higher.

Once the capacity drops below 80%, or if there is a message in Battery Health that the battery is not meeting peak performance expectations, it’s time to change the battery→iPhone Battery Replacement - Official Apple Supportx

odus228 wrote:

Why does my battery capacity keep dropping since the new iPhone 15 came out?

Your battery capacity has been dropping since it left the factory.