I have been searching for a motor for my project for some time now. Its not exactly an e-foil, but this forum is the closest I have been able to find; as far as utilizing a submersible sensor less brushless motor, waterproof esc’s, lifepo4 battery packs, etc.
The project is a small submersible centrifugal pump system that is backpackable. Since it being hiked in, I would like to use the power effeciently.
I currently have a working version using a Flipsky 5062 at 160 kv. If the motor data sheet can be believed, it reaches peak efficiency at 5.5 amps, which is near ideal to get a reasonable run time out of my available battery packs. I only have 2 issues with the current motor (if the motor data sheet can be believed). First is that the kv is a bit low at 24 volts. It works great at 36v, but that means backpacking the larger of the battery packs. The second issue is the motor being an outrunner; I dont have the number off the top of my head but the shell spinning underwater with no load causes a fair bit of drag, nearly 1.5 amps increase in running it in open air to running it underwater.
So I am wondering if anyone here might know of a source for an ideal motor. I know that my application is a bit smaller and higher KV rated than typically used for foiling, but I can hope.
The ideal motor would be:
-Inrunner
-24-36v nominal
-200-300kv
-Max effeceiency reached at 5-10 amps
If you haver any thoughts, please let me know. I have thought about putting a close fitting shell around the outrunner bell to see if that would reduce the parasitic drag. However, Im not sure that the ‘pocket’ of water that would be trapped in the narrow gap between the static shell and spinning motor housing wouldnt cause more drag to begin with. More experimentation may be needed.
Ok, so no go with that. How about any company that sells any smaller brushless inrunners (submersible).
I have found, so far:
-Apisqueen
-Flipsky
-DiamondDynamics
-Maytech
I understand that these kind of motors are pretty small for anyone trying to foil, I am just hoping that people may have found sellers that I have missed.
It depends on costs, the best brushless motors are made in either Germany or USA, but come at a cost.
If you go direct to motor manufacturers in china, you can get better than the resellers but for custom wound they come at a cost.
Parasitic drag of outrunners is more of a theoretical problem. With nearly the same setup (same front wing, same rider), I use the same amount of Wh/km with a 63100 and a FR (Lift) motor, so not worth to increase the diameter for that. Direct watercooling of the windigs is also very efficient. It needs more maintenance though, especially in salt watet.
Any chance to use a normal drone motor and make it waterproof yourself? Those usually come with higher kV than boat/eFoil motors
And I too would not worry about outrunner stirring up the water, there is probably many other things that can be improved for moving water before the spinning drag becomes a major inefficiency
@Strongarm - The application is for a smaller centrifugal pump, a source of medium pressure/high volume water used to create suction in a power jet suction system. (Dredging nozzle)
I am currently using a Flipsky 5062 out runner at 160kV. In the first hour of testing the bearings went bad in it and after disassembling it I found that they used cheap bearings. The kV rating is on the low side, and I had to 3d print a scaled up version of the impeller to compensate.
But an inrunner would be much better for my application. The silty water that this operates in has a lot of fine magnetic particles in it that build up on the inside of a outrunner. (Magnetite sand) . Inrunner motors will be better sealed in general agaist silt and muddy water.
@ludwig_bre - I have looked into normalish drone motors. The kv rating on them usually puts them operating at RPM’s that are way too high for an impeller. (I imagine it would cause cavitation on the trailing edge of the impeller blades)
I would look at the 65121 motor or a Manta sealed outrunner.
The 65121 seems to only come in 130kv, but if you gave it a higher voltage then it would spin faster, maybe enough for your needs. 12-14s packs are common for e-bikes and efoils.