Problem on Q128h Motor with s12sh controller 40A

Seems like a lot of amps for the Q128H. It does not have a temperature sensor, but this sounds like the controller or battery cutting out. Can the battery BMS handle 40A? Did you connect a throttle and does that work continuously. What's the battery voltage and capacity?

What is the voltage of the battery when the cut out occurs.
I have a pair of q128h motors installed on a Big Dummy cargo bike with a pair of S12s controllers and LCD 3 displays. When my 14s pack is full I get periodic cutouts similar to what you described. As soon as my battery voltage decreases to below 56 volts the problem goes away. I think the controllers are doing some kind of high voltage shut down. The system seems to have been designed to recognize 13s packs but not 14 s.

Does the display go blank when this happens?Can the LCD8 show the running voltage? If it does, what does it show when the motors stop? If it doesn't put a meter on the battery and see what it shows.

My questions are pointed toward determining if your battery is just too old to power the system. Usually, a bike that runs with wheels in the air and stops with them on the ground has a battery unable to supply sufficient current under load. That could be bad connectors, one or more unbalanced cells, or other.