These would be treated partly the same as an electric bicycle. however, there are problems for you.
I am fully aware of the regulations surrounding electrical bicycles because my best friend happens to be a main supplier of them
There are no rules that cover skateboards and if you are being prosecuted, the prosecutor would rely on a mix of the rules with regard to how would wheelchairs and mobility scooters and electric bicycles.
A powered wheelchair has an upper speed limit of 4 mph, which is a fast walk and are only designed to the pavement
Mobility scooters have an upper speed limit of 8 mph and can be used on the road and pavement.
I imagine that your powered skateboard has a higher limit than that. There are certain requirements with regard to makers nameplates and power outputs etc.
The fact that magistrates may have dismissed other cases simply means that the prosecutors have not convinced that there was an offence,
There is no way that if this is capable of doing more than 4 mph, you can legally ride it on the pavement, and if there are no pedals, it needs to be taxed, MOT, and insured to use it on the road.
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