[bredren]

> A proper design would allow the battery and motor drive to cooperate so when the motor current demand rises to maintain velocity, the battery pack can tell the motor, sorry, I cant give you anymore and the motor drive can then decelerate or simply refuse to continue accelerating.

These are good thoughts though even in your solution I suspect it points toward the idea that the design is fundamentally unsafe.

The reason is if the motor decelerates you still must be prepared for your weight to shift, even gradually.

[shkkmo]

On a self balacing PEV, if the motor decelerates on it's own (without a weight shift from the rider), the resulting weight shift will not be gradual. You might tip forward slightly slower in comparison but the nose dive would still happen pretty much immediately. This is because in order to maintain speed, the CoM must be in front of the balance point.

The design of self-balancing PEVs isn't fundentally unsafe, but it (like most sports and means of transportation) does carry risks that you should be aware of and compensate for.