Generally speaking, this situation is rare. You can check the battery health through our education first. Under normal use, the battery health of iPhone is above 85% within one year and above 75% within two years. But if you use it for a year and it drops by 80%, there are only two possibilities. One is that you bought a fake, and the other is that you often commit the behavior of damaging the battery mentioned in the previous chapter. I have met people who have been charged several times a day for playing card games. As a result, the health of mobile phone batteries dropped to 78% in less than half a year.
2. The battery management IC is damaged
This situation is mostly because the mobile phone falls to the ground, which leads to the disconnection of motherboard components, and the probability is very small. If the battery is not charged, it is said that the motherboard is damaged, and the store will charge you more than 500 so-called motherboard replacement fees. In fact, it only takes more than 100 to replace the power IC.
3. The charger is not original, and the charging cable is damaged.
This is easy to handle. Just ask someone for an original iPhone charger and charging cable to try.
4, mobile phone system failure
At the same time, press the power button +Home button until the Apple Logo appears, and forcibly restart the iPhone, which should be solved.
5. The gold finger of the charging port is oxidized or dirty.
Scrape off the gold finger of the charging port on the iPhone with the Sim card pin that comes with the iPhone, and try to scrape off some oxides (generally, the old iPhone with this problem must have been used for more than 1-2 years).