How to maintain battery health on iPhone 14?

There is currently nothing wrong with your iPhone’s battery health, in fact it is declining at the expected rate. You can expect your iPhone to decline 1% battery health a month, so after 2 months of your iPhone, it has declined 98%. Note that the decline isn’t always linear and you may notice a few more or less percent decline on a monthly basis. You should only go to a Service Provider when it reaches 80%, that is when the battery has significantly degraded and needs a replacement.

You can review these support resources too:

iPhone battery and performance - Apple Support

Batteries - Maximizing Performance - Apple

Battery Health always declines. This is normal.

You might not be aware that Apple always rounds down any tenths of a percent to a whole number. So, for example your battery health might have been 99.0% and the battery declined to 98.9%.

The battery health only declined .1%, but because of the rounding down, it looks like your battery declined from 99% to 98%......a full 1%.....when it really only declined .1%.

After a year, your battery will be in the 88-89% range. When the battery health has declined to 80%, it is time to replace the battery.

You will drive yourself crazy if you are checking the battery all the time. You only need to check it few times a year.....maybe every 6 months or so.