Hard power cutoff idea


What do you folks think of this?

I mount it inside the battery box with some sort of rotational spring and a latch on the outside. Hook the ankle strap up to the latch so what when I fall off the board it yanks the latch, releases the spring which rotates the knob and shuts off the power. Obviously there’d have to be a secondary release that let me loose from the board, but that’s just velcro.

This seems easier than a solenoid, relay or contactor.

What are your thoughts? If we don’t see any problems with the basic idea I’ll try to model up a complete setup for review.


Interesting idea. Might rely on too many mechanical parts to be failproof? I bought a used solenoid on ebay (as have others) so am playing with that. Works fine on my bench though It’s a little bulky. Solenoid


How do you plan to re-arm it?
Getting out of the water to get the board ready again will be a major pain :slight_smile:

I would only see that safety needed if something starts smoking inside. but it seems overkill for when you just fall off… setting you ESC to 0 should be enough.

Has anyone experienced a board running away because the ESC refused to stop when it should have?


You would re-arm it by twisting it back until the spring lock mechanism (TBD) latches and then attach the breakaway strap.

I come from the Esk8 world and I actually have had 2 runaways. The first one was caused by a static hit (not terribly likely on an eFoil) and the second was a code error. Actually both were code errors of some type. So setting the ESC to 0 makes a lot of assumptions about the state of the rest of the system that may not be true. Especially if you get water intrusion.