When your phone battery cannot last you a whole day, it’s time for a new battery. A phone battery capacity goes slowly down as time goes by.
The two diagrams below show battery level trend. When a battery is with high capacity, the percentage will go slowly down, otherwise sharply down. It’s the same case when charging it up. It always takes longer time to charge up a high capacity battery, and shorter for a low capacity one.
Now you know how to tell a battery capacity and when to get it replaced.
phone battery level trend (high capacity)
phone battery level (low capacity)
But batteries with same capacity can differ a lot from each other. As we all know, battery capacity, or battery life, goes slowly down in year scale. For a good quality battery, the capacity goes down slowly; but for a poor one, it can be quite steep.
The capacity of a battery is very important, because it determines how long it can power your phone.
battery capacity trend (good quality)
battery capacity trend (
But a proper and stable voltage a battery can provide to the motherboard of a phone matters even more than the capacity of a battery, because if it fails to output minimum voltage for a motherboard, the phone might die or restart.
That explains why phones with newly replaced batteries die or restart with no reason. Components, including all kinds of integrated chips, camera, speaker, microphone, compass etc. on a motherboard work under specific voltage window. If a battery fails to provide proper voltage, either too low or too high, those components may be malfunctional, sometimes even damaged.
The two diagrams below show battery voltage output trend for good and poor battery. For a good quality battery, even though the capacity of it is quite low after a few years, it can still provide proper voltage. For a bad quality one, it’s a different story: even though the capacity of it is still quite high, it cannot power a motherboard.
4.2V, 3.8V, 20%, 70% in the diagram are just an example. They vary among different batteries.
battery voltage output (good quality)
battery voltage output (poor quality)
A lady customer called in our shop and asked for help yesterday. Her samsung phone had a new battery replaced recently, but it restarted randomly. We checked the phone and found something unusual.
In the short footage below, you can notice that within 2 minutes, the battery level drops from 70% to 69% and then to 68%. And the phone was doing nothing at all! For a quality battery, it’s not supposed be like this. We doubt that the quality is too bad and it cannot output proper voltage to power the motherboard. A quality battery was ordered and installed, and issue sorted out.