Question: how do you know if your cell phone battery is bad?
Answer: Battery drains easily. Batteries perform at its best in the first 2 years. ... 
Phone does not charge after being plugged in. This is another common sign of a bad battery. ... 
The phone doesn't hold the charger. If the battery has started to deteriorate, the device won't stay on for long. ... 
Phone restarts on its own.