1. The charger is used incorrectly
2, data line aging
3. Cell phone battery is damaged
Can not fast charge, one of the three must have a problem, in order to achieve the purpose of fast charge, charger, data cable, mobile phone must support fast charge.
Charger use error, originally 9 volt 2 amp charger, used into 5 volt 2 amp, naturally can not be fast charging. Because the charger can support the power is 10 watts.
The same is true for data cables and mobile phones. If the long-term use of the data cable or mobile phone causes its internal damage, it will also lead to too low charging power, resulting in too slow charging speed.
There is also a case of internal judgment error, resulting in the charger mistakenly believing that the phone does not support fast charging. For example, using a charger of a different brand from the mobile phone to charge, sometimes even if the mobile phone supports fast charging, it will not be fast charging.