It is the most suitable choice for Redmi K40 to use the original 3A charger. This is because the battery capacity and charging requirements of Redmi K40 are relatively small, and the charger of 3A will not generate excessive current load on the mobile phone. Using the original charger can ensure the safety and stability of charging, and at the same time, it can protect the health of mobile phone battery to the maximum extent.

6A charger can also charge Redmi K40, but the high current will cause some damage to the mobile phone battery, and the price is higher. In order to ensure the normal use of Redmi K40 and prolong the battery life, it is recommended to use the original 3A charger.