Hi Tom,
Presumably, the battery power disappears altogether
(battery gauge LEDs on the throttle go off as well) and instantly comes back on when the battery is turned off and back on again?
It could be due to a poor connection on the keyswitch which could fail under load, and the movement of the switch temporarily improves the poor connection enough for voltage to flow again. Check out
this post for more details.
It could also be a problem with a weak
(faulty) battery cell whose individual voltage drops too far as soon as any load is applied, as this would cause the battery's
BMS to shut of the power to protect the low voltage cell.
Another possible cause could be an intermittent short circuit which overloads the Battery's
BMS causing it to shut off power to protect the battery.
Check carefully for signs of damage to the wires, especially where they exit the motor and are secured to the motor's axle. If the retaining clip has come loose, the insulation of the wires can soon be rubbed through by the centre of the rotating cooling fan/disc mount assembly which could cause a direct short circuit across the battery feed wires.
Alan
