eLofty Direct Drive Discussions-read before buying

Alright, I’ll set them even higher. I guess that shouldn’t affect the heat much as long as I use them only to have a torquey start.

However if I use the high current to climb hills at high speed, th n for sure it’s going to heat up a lot more.

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Edit: @rpasichnyk confirmed that there is a bug which causes the average consumption in the web plots to be higher than it actually is. I’ll post an update once the bug has been taken care of.

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In my opinion you can set whatever max current you want but after you saturate the stator then all the extra current goes in heat and more stress on VESC and do not get much more performance out of it. Would be nice if someone knows how to estimate the max current rating for each motor.

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https://ieeexplore.ieee.org/document/5947918
I’ll try to read it when I have time.

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Nice! Will read it too. Thanks for the input.

Yes you are probably right. Somehow I feel a difference in low end torque between 60A and 80A, going up a long incline is not a good Idea I guess. According to Metr. my highest drawn motor amps are 100A for two motors, so @mishrasubhransu `s 50A seems to be a good fit.

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Thst also depends on the battery you have. I also do in the same way with my direct drive. Started from 50A and now I am at 70A per motor, but the problem is that I hit the battery max. I can get up to 120A from two motors but battery is at max already. Actually even passed the limit I set :cry: Seems unity is not so fast in limiting the battery drawing. For sure not the best way to test them but no idea how to then

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A very simple test would be to start from rest(from same location everytime) and max the throttle. We do this for different max current setting. Plot the distance(from metr pro ) covered in 10 seconds vs the max current. At some current the plot should flatten out. That’s when you know it has saturated and is not longer increasing the acceleration.

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The problem is stay on top of the board with full throttle :rofl: Never gave full throttle all in once. Maybe with a slope is easier to hit the saturation point. I guess is a sigmoid curve

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Yeah, slope will definitely help in this regard. We can even just plot the velocity vs max current. That’s a good indicator too.

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In my mind also the internal resistance should give you a way to estimate the amount of current. No?

No. It’s just the property of material and I guess the amount of core material

The magnetizing field H is proportional to number of turns*current

From wikipedia we have:
“When an external magnetizing field H is applied to the material, it penetrates the material and aligns the domains, causing their tiny magnetic fields to turn and align parallel to the external field, adding together to create a large magnetic field B which extends out from the material. This is called magnetization. The stronger the external magnetic field H , the more the domains align, yielding a higher magnetic flux density B . Eventually, at a certain external magnetic field, the domain walls have moved as far as they can, and the domains are as aligned as the crystal structure allows them to be, so there is negligible change in the domain structure on increasing the external magnetic field above this. The magnetization remains nearly constant, and is said to have saturated”

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now we have to figure it out how to calculate or measure that.

I’m on 70/-70A and during long uphills I’ll get cutoff

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Cut off for temp limits?

No idea yet but here a session with cutout

@rpasichnyk I’m unable to upload the recordings:

The values are a bit weird. How can be that the speed is 5kmh with almost 80A motor current? Were the setting wrong for motor poles and wheel size?
I don’t see the motor temp. I thought this drive has it.

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If I remember correctly I was going up a very very steep hill (San Francisco).

I’ve 150mm wheels and 20 motor poles in the metr settings

Edit: there is no temp sensor on the motor

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How do you set the speed limit? I’m using flipsky new remote over uart

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Try again, if it doesn’t work, Settings - Show Logs - mail to support@metr.at

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