As the latest system, IOS 14 integrates a series of new functions, and the smooth use of these functions obviously requires a price. The more functions, the more power consumption of the mobile phone. The burden of the whole system will increase greatly. Even the closed system of iOS system can be optimized, but the model of five years ago can't bear it from the hardware, which will inevitably lead to faster power failure.
In addition to system factors, there are also health problems of the battery itself. The system battery of iOS mobile phone is not durable. Generally, it will obviously age after 2-3 years. At this time, the most remarkable feature is the fast power failure, which was the case with Apple's 5S before. Power failure is too fast in the later period. Sometimes it seems that 80% of the power fluctuates up and down, and then it drops below 50% after a while, and then it is not unusual to charge it twice a day. Therefore, it is found that the power failure is fast now, and whether it is the aging factor of the battery itself can also be considered.
If the subsequent power failure is faster and faster, you can consider changing the battery. Upgrading the old model to the new system is not recommended. Personally, I never recommend upgrading the iPhone to the latest system version. Many people always think that the newer the system, the better, but it is not.
New systems are usually more bloated, which is a burden to many old models. It will not only affect the use of electrical power consumption, but also affect the startup speed and system fluency. Similar to the model that has been used for 5 years, in fact, upgrading to 13 is almost the same, and upgrading to 14 is still a bit reluctant. Not surprisingly, it is estimated that iOS 15 is an unsupported model. In fact, in most cases, even if we don't upgrade the system, the iPhone can still be positive.