A poor connection will typically fail more when higher current is trying to pass through it
(when load is applied to the motor) .
If the voltage drop was due to an excessive load from a faulty motor or controller, then the current would read very high on the Wattmeter, but I did not notice any high current being drawn when the fault condition was active in the video.
What is the maximum current recorded on the wattmeter when the battery is turned on with the fault active?
As you cannot see low voltage electricity, you will need to use a voltmeter to locate the point at which the voltage drops from 50V to 40V
(while the fault is active).
Simply start at the battery output wires and measure the voltage as you work towards the wattmeter.
If you only have 40V or less at the battery output wires, then the fault is somewhere within the battery or the battery holder unit.
If you place the meter probes across the switch connection
(while the fault is active) you would be able to measure at least 10V if poor switch contacts were causing the fault.
I would suspect the battery or bms, have you tried another battery?
I am convinced it is a poor physical connection rather than a failed electronic component.
The
BMS is comprised of solid state components, which are not usually affected by physical movement unless there is a poor soldered joint between a component
(or wire) and the
BMS circuit board, as the fault was definitely affected when the trike was jarred.
If the fault is on the battery side, I think it is more likely to be the key switch contacts within the battery holder, or poor contacts in the connector between the battery and the holder where the two items separate each time the battery is physically removed.
Alan