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Temperature cutoffs with Lacroix Nazaré motors


I‘m somewhat irregularly experiencing what I believe to be motor temperature cutoffs from the motors on my Lacroix Nazaré.
I live in the sticks so to speak and have a lot of hills and so on, quite often my motors get hot, around 100C and I get little jolts, yesterday I even had some on relatively flat ground.
I then have to stop, see the temperature plummet after a few minutes and I can ride on.
Is there something to mitigate this problem?
I don’t want to stop for a break, I want to keep riding.
Also, what do I do in the summer?
Stop every ten minutes?

Lacroix customer service told me to „update the settings to current Stormcore settings“ whatever that means.
Does this mean I could up the temperature limit?
Wouldn’t that kill the motors quicker?

I’ve attached pictures of the motor temperatures from the last two rides, on one you can clearly see the temperature dropping.

Wow 100C is VERY hot for a motor, what size are yours?

Might be worth considering some 63100’s for better heat performance

I think you can just increase the thermal cutoff for them but once you get over a certain temperature it can start to demagnitize the magnets, @hummie knows what that is

The best possible solution is 4wd + lower motor current settings but that is a much more expensive and involved mod

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they are the stock 6389 190kv motors, the stock ones on my board.
I don’t know why they get so hot, is it because i’m 100kg (220lbs)?

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I suppose the combination of that / hard riding would do it - that’s not even that heavy but compared to me, I can heat up 6374’s to nearly 80, and I’m only 150 lbs


One option would be to go for bigger motors. Larger motors have a larger thermal mass to soak up more heat before reaching the thermal cutoff, and also have more surface area to radiate that heat away.

Another would be to add some active cooling if possible. If your motors have holes in the back of the can, you can add a 3d-printed impeller to the motor’s can so that as it spins, it sucks air through the motor, cooling it.

Of course there’s also the software fix: Lower your battery and motor current settings to limit your heat generation. Obviously this is less than ideal because it also reduces your performance and thus fun.


I’m just laying this out without givning it too much thought since i never used sensored motors but… could perhaps the temperature calibration setting in vesc tool be a bit off?

Maybe the “stormcore setting” would fix that.

I just thought your wh/km was quite low if this is a log where you punish the motors to overheat🧐

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Yeah, that’s possible too. Could always crack open one of the motors and add an extra independent temperature sensor to verify.

It would also be possible to verify by putting the motor in a place of known temperature, like a freezer , and seeing if the temperature sensor agrees with what the freezer should be.
Likewise with an oven set as low as it will go - Mine will go down to 175F, which is about 80C, just about the maximum temperature you’d want to subject your magnets to. Might be best to only put the stator assembly in there, just in case.

I think my ebike’s hub motor thermistor is out of whack, so I’m waiting for a nice 0-degree-celsius day to reset my thermal calibration (the dashboard uses a zero point and a slope coefficient)

Pfff I run mine at 90 in the summer. It’s fiiiine. The epoxy melts at 120


Are you sure that telemetry is correct?
8.3 wh/km seems pretty ridiculous for pnums

That’s just one side.

That’s still WAY low in my opinion. 16.3wh/km? That’s like nothin haha.


@exx are you sure your motors are actually getting that hot? 100c is enough to boil water, which would definitely burn your bare skin if you touch it. Are you able to touch your motors when you get these temp cut-offs?

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For what he is doing kinda. BUT my average is also in the 16-18wh/km range though I’m far from overheating my board/motors (FS BH 6374)

I weigh the same so my guess is also on the bad temp sensor

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Oh shit my bad, I was comparing to my numbers which are in wh/mi not wh/km.

Off topic, but how does one convert from wh/km to wh/km and back?


I let metr do the work :man_shrugging:t3:

Or google

Google conversion

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Ah nice, didnt know that google had a converter for that. Thanks dude :metal:

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That’s why they are hot:

High RPMs create high core losses, even at very low amps. You can actually heat up a motor by spinning it fast with a drill. The magnets induce currents into the stator and the stator gets hot.
Riding with high average speed simply warms them up.


Bear in mind that the temperature is measured at the coils/stator, and the magnets/rotor, which is what you can touch from the outside, are not thermally coupled to the stator - that air gap between them, plus the can spinning in free air, can result in an extreme temperature difference between the stator and the can - deltas well in excess of 30 degrees are not hard to achieve, especially if the ambient air temp is low.


You need to adjust your settings. Results you are getting don’t seem to be what it should be.

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I thought for typical outrunners, most losses are in the copper?

I remember @hummieee mentioning something like 90% copper vs 10% iron losses (eddy currents + hysteresis)