Noob question thread! 2020_Summer

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.

If you mean are the motors actually hot, then yes. Is there a chance the temp sensor would somehow not be calibrated correctly? Is there a chance that doing the motor detection at around 25c is causing an intolerance in the resistance and causing them to overheat? Should I try a motor detection while they are warmed up at all?

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Hmm. Thats less than ideal dude, i think you need bigger motors.

Regarding the detections and inductance and all that other fancy shit, thats way over my head :sweat_smile:

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Only in Europe so freaking awesome :call_me_hand:

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So I filled the area with epoxy yesterday, do I need to sand it down to even out the area?

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The real question is “do I want to sand it down?”
Cosmetically, it’ll cause a bump in your griptape. You can sand it but if your wires weren’t tucked in far enough, you risk sanding the cable’s insulation. Proceed with caution imo

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Okay, it mostly pretty flat and even, except the excess epoxy on the sides, so I will see what I can do

Different resistors used as temp sensors do have different “base” resistance at room temp (in marlin config for 3d printers need to tell it which thermistor is being used 10k 100k and like 20 options for different resistance to temp tables for different sensors I think). Unfortunately don’t know if you can somehow adjust what the vesc does with regard to the resistance to temp conversion.

What epoxy did you use?
I’m planning to do something similar but with tinned braided copper cable

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terminologiy question.

what’s nominally mean here? my understanding is just meant “in name”. or “as it’s labeled” or “as it’s called”. so… I thought it had very little technical distinction and couldn’t be closer to any particular number.

West systems 650

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So I sanded it down and the bumps are smoother and not as obvious so should I be fine with the griptape?

It depends on your cutoff settings. LiPo cells get angry if you discharge them below about ~3v/cell, whereas a lot of li-ion cells are rated to be discharged al the way down to 2.5v/cell. That lower discharge cutoff voltage lowers the average or nominal voltage.

Similarly the “HV” lipos and li-ions that have a 4.25, 4.3 or 4.35v maximum voltage end up with a higher nominal voltage like 3.65, 3.75 or 3.8v/cell.

The nominal voltage is basically the average voltage across your discharge. So if you only go from 4v to 3v, then your nominal is more like 3.5, or if you go from 4.2 to 3.5, your nominal would be something like 3.8 or 3.9.