Hi Martin,
It sounds to me as if your battery's
BMS may be cutting off the power under high load due to excessive voltage drop on one or more of the battery's cells.
As soon as the controller cuts out, the battery/cell voltage will often recover quite quickly and enable the controller to start working normally again, but some batteries require the power to be cycled Off and back On again in order to reset the
BMS after a Low Voltage Cutout has occurred.
If the cutting out was due to the controller simply getting too hot, it would take much longer than a few seconds for the controller to cool down sufficiently to allow it to start working again.
Alan
