One reason why 1% battery might last a long time. Your phone is playing the safe 1% charge left for you to use Bluetooth, stream a movie, or download a system update. But if you are scrolling through a feed, 1% is gone last in a while. There is also a bit of psychology in it when you see when your phone is going to turn off. It encourages you to the plugin to electricity as soon as possible. Now modern batteries cannot fully be charged or fully drained. The smartphone has a special protection circuit in it to save its battery. When it is heard the most, and you have zero percent of charge. A tiny bit of juice is left in it, but your device is not designed to use it if a modern battery magically got to the actual to zero. Then you have to through it in the toilet and get a new phone.