33w charger to 30w mobile phone charging will cause harm to the mobile phone battery, this is because the rated power of 33w charger is larger than the rated power of 30w mobile phone, the rated power of the two does not match, if the 33w charger to 30w mobile phone charging, the mobile phone battery will explode. Therefore, the 33w charger to charge the 3Ow mobile phone will cause damage to the mobile phone battery.
Charging once in a while is not much harm, and it will certainly cause damage to the battery if it is used all the time