iPhone 15 battery capacity drop in a week

Thanks for the information.

The battery in the iPhone 15 is designed to go up to 1,000 Charge Cycles before the battery declines to 80% Maximum Capacity under ideal conditions.

That works out to an expected 1% average decline in Maximum Capacity for every 50 Charge Cycles.

Your battery has completed 215 Charge Cycles. So, 215 divided by 50 = 4.3%

100% minus 4.3% = 95.7%....which is about 96% because Apple does not display tenths of a percent.

So 100% minus 4% = 96%. Your battery display is exactly the same.....96%.

This information confirms that your battery is operating normally. If you take your phone in to the Apple Store / Genius Bar, they will tell you exactly the same thing.

It is not unusual for a battery to decline 2-3% suddenly and then not decline at all for the next month or two because batteries are chemical devices. They do not decline in a constant way.

When your battery has completed 500 Charge Cycles, the battery Maximum Capacity will be about 90%. There is no need to check the battery constantly. It will do what it will do.

The measure of battery health deterioration/drainage is subjective and can vary depending on individual usage patterns. There is no universal standard to determine whether the battery health deterioration/drainage is normal or abnormal because it heavily relies on how the battery is used and maintained.

Protect & Prolong the Life of your iPhone's Battery:

1. About the battery usage on your iPhone, iPad, and iPod touch ...
2. Batteries - Maximising Performance - Apple (IN)
3. iPhone Battery and Performance

Try to monitor Battery usage by iPhone Activity as shown below

What is shown under battery usage? Checking that would give you an indication of the usage behavior.

1. Background Activity
2. Notifications
3. Connected to Charger
4. Or any Other

See the pic below (iPhone 12 Pro iOS 17.3.1)

"Show Activity" feature will show you more info see the pic below

Try some of these options too.

To prolong the life of your iPhone battery, you can follow these tips and best practices:

To prolong the life of your iPhone battery, you can follow these tips and best practices:

1. Optimize Battery Charging: Enable the "Optimized Battery Charging" feature on your iPhone. It helps reduce the wear on the battery by slowing down the battery aging process. You can find this option in Settings > Battery > Battery Health. About Optimized Battery Charging on your iPhone - Apple Support (IN)
2. Avoid Extreme Temperatures: Extreme temperatures, both hot and cold, can negatively impact your battery life. Avoid exposing your iPhone to excessive heat or cold, such as leaving it in direct sunlight or in a freezing car.If your iPhone or iPad gets too hot or too cold – Apple Support (UK)
3. Use Original Chargers and Cables: Always use Apple's original chargers and cables or certified third-party accessories. Low-quality chargers or cables can damage the battery and reduce its lifespan. Identify counterfeit or uncertified Lightning connector accessories - Apple Support (IN)
4. Avoid Draining the Battery to Zero: Charge it whenever the charge becomes lower than 20%. The rest is up to you when to charge. how long to charge, how often to charge, which adapter to use starting from 5W to 140W USB-C Power Adapter etc.
5. Optimize Display Settings: Adjust your display settings to optimize battery life. Lower the screen brightness, enable auto-brightness, and use shorter screen timeout durations. Adjust the display and text size on iPhone - Apple Support (IN)
6. Minimize Background App Refresh: Limit the number of apps allowed to refresh in the background. Go to Settings > General > Background App Refresh and disable it for apps that don't require real-time updates. Switch apps on your iPhone, iPad, or iPod touch - Apple Support (IN)
7. Disable Push Email: Push email notifications can drain your battery quickly. Instead, set your email accounts to fetch data manually or at longer intervals. You can change this setting in Settings > Mail > Accounts > Fetch New Data.

While we will avoid posting cut and paste boilerplate as a reply, we do need more information to make any kind of evaluation at this point.

• Was the iPhone 15 purchases as new, refurbished or used?
• What is the actual Maximum Capacity of the battery at this time?
• How many Charge Cycles on the battery?
• What iOS version is installed on the iPhone 15?