30w charger can be charged to other mobile phones (most), the current charger standard is generally 5V\/1A, 30w fast charge to other mobile phones when charging, if you do not support 30w fast charge protocol, will automatically drop to 5V\/1A standard. Although it is said in theory, it is not completely correct, I have tried Huawei 22.5w fast charge to Xiaomi 8 charge, completely charged, obviously does not support the 5V\/1A standard.