Battery recalibration is a process used to ensure a smartphone's battery indicator accurately reflects its actual charge level. Over time, batteries can degrade due to chemical changes, which may cause the phone's display to show a different battery level than what's actually available. This can lead to issues such as the phone refusing to charge beyond a certain percentage or shutting off unexpectedly even when the battery appears to have charge left. Recalibration can help improve the accuracy of the battery reading, but it may not fix problems if the battery has lost 20% or more of its original capacity, as noted by Apple. The iPhone 15 is designed to retain 80% of its battery capacity after 1,000 charge cycles (500 cycles for the iPhone 14). Once this threshold is exceeded, it is generally recommended to replace the battery or the phone. Users can check their battery's health on an iPhone by going to Settings > Battery > Battery Health, and on Android devices, it can be found in Settings > Battery. Newer Android models, such as the Pixel 8a, provide an estimate of the battery's current capacity compared to a new one. There is no universal method for recalibrating a battery, and the process varies by device. For most Android phones, the approach involves fully discharging the phone until it turns off, then charging it for two hours after it reaches 100%. If the phone doesn't show 100% charge, the process is repeated until it does. Apple has used software-based recalibration in the past, such as with the iOS 14.5 update, which allowed certain iPhone models to recalibrate automatically over time without needing to discharge the battery. If recalibration fails, Apple offers free battery replacements under warranty. Recalibration is helpful when the battery indicator is misleading, such as when a phone turns off unexpectedly despite showing remaining charge. However, it does not address other battery-related issues, such as apps using excessive power. It also cannot restore the battery’s original capacity, as battery degradation is a natural and irreversible process. On newer Pixel devices, a feature called Battery Health Assistance, introduced with Android 16, intentionally reduces the battery's maximum voltage over time to slow aging. This feature is enabled by default on the Pixel 9a and cannot be disabled on other models. If this feature is active, recalibration will not have any effect on battery performance.