We can also test the charger's performance during use. A slight temperature rise in the battery towards the end of charging is normal, but if the battery becomes noticeably hot, it indicates the charger failed to detect when the battery was fully charged, resulting in overcharging, which is detrimental to battery life.
Many chargers, while not overcharging, suffer from undercharging, directly manifesting as short battery discharge time, i.e., short standby and talk time for the phone. Users using the original new battery can compare the approximate reference time provided in the instruction manual. If there is a significant difference between the reference value and actual usage, there is reason to suspect a problem with the charger. Of course, other factors such as battery quality and the phone's usage environment cannot be ruled out.
