Why do older phones only get to 100% after they hit a seemingly arbitrary cap and it’s plugged in again later?
In: Technology
All modern phones use “lithium” technology. It allows a lot more energy to be stored than older types. But they are easily damaged if not charged up very carefully. It is also difficult to know how much they are charged. So phones use a small computer to control the battery charging. It records how much it has been charged, and how much energy has been used, and simply tries to guess how full they are. When the battery is new and healthy, the computer can detect when it is actually completely full, and when it is actually almost empty. It can then adjust it’s guess to be better. But if it is never let to go flat or charged to full, over time the guesses get worse. This is not so noticeable for a healthy battery, but an old one can behave differently, so the guesses the computer makes become wrong quickly. Often, the computer thinks the battery is full, so it only charges it very slowly, even if it is only partly charged. Or, it thinks there is plenty of life left when it is empty, so the phone stops working suddenly. Leaving the phone on charge for 24 hours even if it says it is full, then letting it get completely flat will help the computer to adjust its guesses a bit better.
Latest Answers