Motor stalling. I am guessing at no load.

[ElMaco]

I have put a Leaf motor in my boat. It's an EM-57 with a gen 3 OI board.
The other day when we were out on a test run the motor suddenly stalled and I believe came to a complete stop. Boat still making some speed. After a little while it came on again. This repeated a few times until I made it back to berth. To make sure to have controlled starts I shut of the motor and restarted the rest of the times it happened.

Today we ran a few tests still tied to land. I suspected a few things about noise from pumps to bad throttle. But everything worked as good as one could expect. That led me to believe that it is happening when I am reaching the speed where I am not accelerating any more at a certain throttle position.Tied to dock we are constantly "accelerating" from a motor perspective. Does that make any sense?

What can I do to confirm this or what other tests can I run?

A couple of photos for attention:

[uhi22]

Nice project Just a few ideas with my limited knowledge:
- Is there already a "boat mode" implemented? For car usage, the throttle is just giving a torque request, which leads to increasing rpm on an dry boat. As far as I know for boat a speed regulator would be normally used, to have a certain thottle position leading to a certain, regulated RPM.
- You could observe the spot values of the pot and the error information (lasterr), maybe this gives a hint what is going wrong.
- Maybe also a temperature issue or low voltage, should be visible in the spot values.

[ElMaco]

Thanks Uhi22,

I was thinking the same ways you are, regarding the differences between a car and a boat, at first. But then I was thinking about a sort of ideal case where a car is given a certain small amount of throttle on a long flat road. The car would accelerate to a certain point where all universe’s forces are at equilibrium, and the car would make constant speed. What is the big difference between that, ideal, case and my boat. Would the motor in the car suddenly want to stop when constant speed was achieved?

When it comes to temp and voltage I am fairly sure that is not the issue since we have about 390V in the batteries and the temperatures were constantly monitored @ about 20° to 30° (I am assuming Celsius).

I’ll run some more tests today as you suggest, logging throttle pot, rpm (speed), temperatures, status and lasterr.

[uhi22]

Your example sounds plausible. I guess the difference is while accelerating. Giving full throttle at a car will just lead to high torque and a motor rpm linear with vehicle speed. At at boat, this will cause a lot of slip, maybe overturning the motor decreased accelerating. Of course, an experienced operator could compensate this lack, so No problem for some trials.

[johu]

I know OI foc doesn't like fast spinup. There is a boat mode where throttle controls speed, currently not sure how to activate it... Check cruisemode or potmode

[ElMaco]

@Zieg, I noticed in another thread that you have your motor "mounted backwards". I have as well, for practical physical reasons. Have you made any settings specifically for running the motor backwards?

because the motor is running in reverse

Also, since I am running a slow boat, with a huge propeller, I am running low RPMs. I have limited the revs to 3 000 RPM, 100 Hz (with my setup) if I remember correctly. Are there any specific settings I should be aware of running only low RPMs? I am using the stock ~8:1 reduction gearbox that came with the motor, so prop revs are max 375 RPM (about 45 km/h in a LEAF with 205/55-16 tires). I don't need anything above 3 000 RPM. I want stable and smooth operation from 0 to 3 000.

[Zieg]

Cool, first time I've been summoned to a thread, haha.

Well to get the mechanical part out of the way because it's simple, make sure you have proper oiling in the reducer box since spinning reverse doesn't get oil to the places it needs to go.

As for configuration, there's nothing specific in the settings that has to be done for reverse operation aside from either inverting the direction switch polarity or changing it in settings. I don't think that applies if you're using boat mode, though. Be aware that if you mess up the synofs badly enough it can make the motor spin the wrong direction, which may cause all sorts of other problems. I learned the hard way that it's possible to get into a 'double negative' type situation where the switch is wrong but so is the syncofs so when you press forward you move forward, but the motor is spinning in the opposite direction it thinks it is. Hope that makes sense.

I also had to adjust my syncadv in the opposite direction of what we intuitively thought would work. However, there's a fork in the foc github which includes a test fix in the form of some different math. That seems to have completely fixed the issues I was having with unwanted acceleration. Not sure if it's been merged back into the main branch yet.

I agree with the suggestion above to log potnom too just to rule out it being an issue with the deadzone being too small or something. The only time my motor stalled on me was when I had the aforementioned syncofs very wrong, at low throttle it seemed to drive normally but as soon as I goosed it, bam. Desat error in the middle of an intersection.

[ElMaco]

Thanks for the quick and qualitative reply @Zieg.

Regarding reduction gear oiling. I have filled it to the supposed level for ordinary use. Are you suggesting to add more?

I would believe my syncofs is about right. I haven't had any issues with the motor starting in the wrong direction, as you describe. I have however had issues with the motor not starting at all, from time to time. I am assuming that this has the same root cause as the stalling. Just haven't found it yet.

Haven't tried boat mode to any extent yet. But I'm getting there soon enough. Starting a separate thread on that.

Regarding potnom and dead zone, how can I rule this out? Are there any tests I can do?

[Zieg]

by ElMaco » Wed Jul 09, 2025 7:06 am
I have filled it to the supposed level for ordinary use. Are you suggesting to add more?

Ah, no, there's more you have to do, unfortunately. See when the car is driving forward, the differential ring gear acts like a pump by pulling oil from the bottom of the case and slinging it upward into a pocket in the housing. You can see the teeth of the gear are quite close to the outside of the housing on the side of the gear that goes 'up', which is how the oil is transported. From there, it runs out a hole and onto the teeth of the intermediate shaft. That's how the teeth between the motor and intermediate shaft are lubricated. It also appears as though oil being slung by the main gear follows some channels on the sides of the housing to reach the bearings on the motor and intermediate shafts. If the motor runs in reverse for prolonged periods there have been issues reported with bearings failing (and I would assume accelerated wear to the gear teeth). What I did was attach a scavenge pump to the drain plug at the bottom of the housing, drill and tap a return line through the side of the housing into the chamber that would normally be filled by the gear teeth running forward, then I drilled some extra holes and carved new channels into the housing to help get the oil where it needs to go. I only have a couple thousand kilometres on the car, but so far so good. Also, mine is an older unit with open bearings. Later reducer boxes (perhaps after 2019, we aren't sure) have shielded bearings. It's unclear if these still need oil passing over them - I personally think they do, but others think not.

Anyway, as far as troubleshooting, the test you can do is go out and record some logs and post them here. I think the reason everyone wants to see potnom is to see if it is reading some value when it is accelerating while it shouldn't be - and to see if it is for some reason going to 0 when the motor seems to stall.