Noob question thread! 2020_Summer

Where did you get the 44.4 A number?

1600w/36v since my motors does not tell me max motor current.

Or would it be /42 since that’s max voltage in 10s?

I did both just incase.

Edit: I think I’m off on this…

I tried that. Imported the file in FreeCAD and tried to derive a drawing but that kinda didnt work because when you import the stl and make a solid out of it, it has a lot of weird triangles on non-flat surfaces and makes it impossible to get the measurements :confused:

You can’t find the amps without at least knowing the voltage the manufacturer assumed those 1600W.

Also motors take as much as you give them. If they run cold, they can take a few more amps. If they’re too hot to touch it’s too much. No complicated math needed

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800w² voltage used 36v 10s4p (32A) setup. But in my end, my motors gets extremely hot due to hills around my area. So I can’t tell for my part.

10S is 42.0V, not 36V

The ebike companies are all full of shit, to put it bluntly.

Get out a multimeter and check :crazy_face:

nominally its 36. I’ll try 42 though.

It’s not even 36 nominally, that’s the silliest part.

It’s closer to 37 than 36.

I think the 36 comes from “lead-acid equivalent” numbers or some horseshit like that.

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isn’t 3.7 lipo?

Really, in science you should just use voltage, and the voltage is 42.

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Basically the ESC will not output more than what the motor amps are set to, and will not pull in more than what the battery amps are set to. It is possible for there to be more amps outputted than inputted because it acting almost like a buck converter, inputting high voltage and low amps, and outputting low voltage and high amps.

Let’s say you have a 10s setup with 60A motor max and 25A battery max. At 5% duty cycle, the motor sees 2.1 volts and outputs the full 60 amps. The motor amps will stay at 60 as the duty cycle rises until in this case, 41.6% duty cycle. This is the point where there is 60A of motor current and also 25A of battery current. From now on, passing this duty cycle will reduce the motor amps while maintaining the 25 battery amps. At 50% duty cycle, there is still 25A of battery current, but now the motor current is reduced to 50A. At a full 95% duty cycle, there is 25A of battery current still, but only 26.3A of motor current.

This is all assuming you are running at 100% current because VESCs usually control current not speed. Above, duty cycle is referring to speed as voltage=speed.

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Sorry, its in the esk8 calc. Lol

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It’s different for each specific cell, but if I recall, a lot of modern li-ion cylindrical cells are almost 37V nominal.

Nominal voltages means very little though to this. The max wattage will come at max voltage.

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Sounds like its esc dependant as said earlier.

Right. I’m still learning these things. Been trying ever since I got the motors with very little info.

You can set whatever you want into the VESC tool, you just have to make sure the numbers you set are safe. ESC doesn’t matter much, I could go out any buy a $50 VESC and set it to 150 amps, it may output that for a few seconds but then die shortly after…

That sounds easy enough. Thanks.

I made a quick graph representing battery/motor current.

X axis is duty cycle, Y axis is Amps.
Red is motor current, blue is battery.

It matches up with the scenario I explained above with 60A motor and 25A battery max.

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Where is @professor_shartsis when you need him

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He might need to explain how he got his pwm numbers. That was 100% confusing.