solve:

1. When the voltage is adjusted to a certain value, it cannot be increased. There are two possibilities: 1) the output voltage limit switch inside the controller is turned on.

2. Long press the "knob" for 0.8 seconds to enter the function menu, then turn right to find UL180 (this value may be any value or the highest value we just adjusted the voltage to).

3. Adjust the parameters to UL250. 2. It may be a coding switch fault in the controller. If it is a fault, it needs to be returned to the factory for repair.