Hey ngeneer, I have made a few robotic boats where I used submerged hobby BLDC motors directly coupled to propellers.
Thanks! I'd sorta been looking that direction, too. Got some submersible toy-boat ducted-propeller thrusters with the aim to get them going with my own code on the nifty Parallax Universal Motor Controller. Looking at starting them very slowly with high-torque Field Oriented Control (FOC) then transition to just to unidirection (~60 RPM) more energy efficient brushless control. the difficulty arises in that there are no hall, or other, position sensors on those submersible BLDC motors.
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Has anyone here "potted" (encased the windings/electronics in epoxy) a motor like the BLDC hoverboard motors?
Polyurethane is better. I have cast circuit boards inside semi hard Polyurethane used for sub sea trawl sensors.
^^^ this ^^^
I did the same thing with a camera that spent 5 months at the bottom of a tank of otters. Worked great.
perfect tips! thank you!
Hey ngeneer, I have made a few robotic boats where I used submerged hobby BLDC motors directly coupled to propellers.
The motors run fine below water but need an oil bath when removed.
I am not sure about long term submergence.
Thanks! I'd sorta been looking that direction, too. Got some submersible toy-boat ducted-propeller thrusters with the aim to get them going with my own code on the nifty Parallax Universal Motor Controller. Looking at starting them very slowly with high-torque Field Oriented Control (FOC) then transition to just to unidirection (~60 RPM) more energy efficient brushless control. the difficulty arises in that there are no hall, or other, position sensors on those submersible BLDC motors.
ngeneer, I just used common hobby ESC (electronic speed control) modules. They are driven by normal hobby RC servo protocol.
The good ESC modules like EMAX can be programmed for soft start and other features, even bi-directional operation.
To control the ESC from the propeller microprocessor just use hobby RC servo programs - there are many examples on OBEX.