For who try/have tried direct drive with outrunner


Sorry to hear that MAC, that really sucks!
Its a great learning lesson for us all thought if it does not feel right check the prop right away. I had a similar issue first day out with my thrust stopping dead, I flipped it up and the propeller was gone but I found it on the bay floor after 2 hours of snorkeling :slight_smile:

On an ESC note, long story short after confirming with a couple guys who know ESC’s very well, they all came to the same conclusion, and I see what they mean happening in this forum all the time with builders as ESC or wire connections meltdown.

Bottom line RC controllers are meant for short bursts for a car or boat to blast forward for 3-8 seconds and be out of sight before letting off on the throttle. With efoils, we draw full power for longer periods of time, and then still keep the power up at 50% when cruising which is a lot of current still. I was told whatever the ESC is rated for like your 200A flier is that you take 60% of 200 (.5*200 = 100A), that is your safe burst draw for long-term use so the motor should not draw more than that at peak, then take 60% of 100A which is 60A continuous and this should allow a long life on an ESC.

The reality is most of us are pushing ESCs way beyond their normal operating limits and the only way to resolve this is to use a smaller motor, or upsize the ESC so your motor is not straining the ESC ever ride or when weeds get stuck in it for only 30 seconds.

Hope this helps shed some light on ESC sizing for readers? :slight_smile:


I think I remember telling you that about a year ago.:grinning:
I was reminded of the alien 420 amp esc being tested over on endless sphere by Luke. Blew up after a few seconds of 100amps.

One reason an ebike controller makes more sense, they have current control.


There is another video like this on the 300A swordfish ESC it did the exact same died in less than a minute as well with about 100A and they compared its AMPS (current) tracking that is built into the swordfish data logger and it was way off. Swordfish data logger said it was at 170+ amps but it died and fried at 100A.

This is why they are RC controllers and not used in human transport :slight_smile:

But just shows why so many smaller ESC’s like the 100A - 200A esc’s trying to be used for Efoiling burn out so quickly. More or less rate the ESC at 25% of rated current and use that as benchmark.
Thanks for sharing Dirkdiggler


Have anyone tried a simple ebike controller? 1-2kg extra are worth the simplicity of no forced cooling need. A simple 24 fet xiechang with IRF transistors will laugh about all you could possibly push into those tiny motors.


I was wanting to use directly in water, outrunner I have seen that problem with regard to direct motor salt water, I’m from Brazil here has Yes many many more distant Beach people will typically for freshwater, and closer anyway, I was wanting to use This setting I’m sorry if I’m talking nonsense I don’t know much more.

EMAX gt5345-170 kv-12s-RMP 6500-80a
ESC HobbyWing SeaKing V3 130A HV ESC BL Motor 6 V/5A BEC
Prob pa rev3 - pacificmeister

will be connected directly without gear box.


I ordered a replacement Flier ESC 380 AMPs. Delivery is scheduled for 4 to 5 weeks. Since I have time to wait I decided to open up my 83100 out runner to see how things looked. There is no sign of being cooked. My biggest fear has always been that there was no good way to keep a dry out runner cool. This is the motor I winded myself. Now its about 116 KV Delta. I am considering going to a Wye configuration to bring the current down farther, I am currently running a 12S.

, IMG_20180629_091936132


I plan to replace the large rear bearing, it has sounded rough since day 1. I also need to build a new Stainless Steel 12mm motor shaft because the shaft materisl I originally used is rusting. I run in fresh water only. No oceans near me.


I think I could have avoided burning up my ESC if I had a thermisister mounted inside my motor and possibly other spots. I am going to try to learn how to build a audible alarm that I can set to go off at safe temperature. Maybe a Ardirino project.


Have a look at titanium, not necessarily more expensive, but great corrosion resistance, easier to machine, and lighter… :slight_smile:

I used that one to replace the shaft on my 80-100, ran it a few time in salty water and it’s as new…
it’s not exactly perfect machining but very easy… I put it in my drill press and used fine sandpaper to bring the diameter down for the bearing, and a metal handsaw to make the circlip groove :slight_smile:


I use this one. I adjusted the beep alarm to 70 degrees @ESC. Works quite good.

DC 12V Red LED Digital Thermometer High Low Alarm -60~125C Temperature with Temp Probe Sensor B3950 10K Temperature Meter


Thanks Mat, Unfortunately I just bought some ss shaft from E-bay minutes before I read your post. Everyday I learn something new I should have tried. I bet most of you guys are already planning your next build. I know I am.


Yea, something just like that. I never have bought any thing from Aliexpress. But here goes. Thanks.


I installed the new ESC and made several improvements. I especially like the temperature display monitoring my cooling water output. It has big 7 segment display that I can read without my glass’s. It also has a warning buzzer that you can set. Its not very load so I don’t think I would hear it inside my battery box. Anyhow I rode it around for about 1/2 hour. Water temp in was about 78F, water temp out 85F. It was working good.


The next day, as soon as I went to use it, the motor was making kind of a grinding noise. It only made the grinding noise in the water. Sounds like the clutch on a drill. it was so bad that it sometimes caused the motor to stall. After about 5 minutes of trying to understand the problem I went home and opened the motor pod up. Everything looked as it should. A very small amount of water was in my dry out-runner. When I got to the water again the problem showed back up. I am thinking bearings?? but they don’t feel that bad. Do motor winding ever short only when drawing heavy current? ESC? I have not changed any ESC settings.


Could a magnet have come unglued from the rotor? this has happened to me before and it makes a kind if grinding sound. In fact it was nearly every magnet in the motor that came unglued in my case, its surprising it still worked. I glued them back on with JB-weld epoxy and they’ve been fine since.


I have the motor completely apart now, Its not the magnets, they look good. Just before I took it apart I ran it in a barrel. I ran it in a deep bath tub like tank I have. After a minute of revving it, I think it got a little better. One observation, on the FWD side of the out runner there is a large bearing. Its used to keep the large magnet shell where it need be, centered over the motor core. That bearing was the slightest bit crooked. Maybe 0.5 mm. The grinding noise frequency seemed to match the RPMs. So I am going to pull the bearings out, clean the surfaces, and install new.


ah yes that makes sense it would be wobbling in its slot. Where did you buy your 80-100? They seem hard to find.


I got the motor on Ebay, from r-mambabrushless. Its a 83100, I have made many changes to the motor.


The motor arrived with a cooling water leak in the core. I contacted the vendor, he was willing to do what he had to, to make things right, Anyhow I fixed it myself. just required disassembly and gasket sealer. Its kind of amazing how much torque that motor has. You probably will not be happy with the 180 KV. I think about 100- 110 KV would be perfect.


i found 1 there but they don’t seem to have stock anymore:

And Alien have quite a few versions, but you need to talk to him to see what he has in stock.

you can also find chinese suppliers… but you need to order a few :slight_smile: