You guys are all crazy… Putting motors on a longboard 
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Absolutely, but having an accusatory tone? As if it were negligence or indifference on his side…
I’m mean how many of his motors have you tested to even make the claim of “puffing” … Have you tested another? Has someone else done the same test and have come up with the same results? You talk of precision … How percise were you when you did your tests? How percise are the instrumentas that you are using? Were you precise in your investigation that @torqueboards is “puffing” the facts? Let’s get real man…those specs, written by the motor maker…It’s marketing material … All of it is…no matter if it’s in paragraph form or bullet points
We’re blasting down the road on a piece of wood with a motor made for an RC plane…We aren’t building mini space shuttles to take us into space…or using it to save people lives … These motors are far from what would be considered precision in certain circles…
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I am new to this and have read for the past two days and not the best at electrics im more of a cnc cad milling kind of guy but I am stuck with once you have your vecs how do you connect that to your throttle controller?? I.e numb chuck or enertion hand held controller also would love other ideas on another way of controlling your throttle thanks delete if im mot ment to write this here
Throttle is controlled wirelessly with with a hand held Transmitter and a Reciever that is conected to the ESC .
@chaka I’m definitely not arguing, but I’m curious about why you make the calculation based off the max charge voltage instead of the nominal voltage? My experience has been that I’m only at 4.2v per cell for 5%-10% of the ride time I get, and then I’m at 3.8v for the majority of the usage. We’ve all seen the lipo and lion discharge histograms… the majority of the line is flat at 3.8.
Is it because we are at the greatest risk of VESC failure during that full voltage period? If so, could we limit amp draw or ERPM to protect ourselves if we’re out of this specification?
I’m about to switch from 8S Lipo to 10S Li-Ion and I’m wondering if it’s necessary to get a new motor (currently using a 245kv, but could go lower to 192KV to align with your suggestion)
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Some people run 245kv on 10s but it can cause problems. That is a really high ERPM. I personally don’t go over 230kv on 10s. The higher you go with ERPM the higher the chance of errors and blowing a drv chip.
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Can’t we limit the erpm through the bldc tool to prevent this issue?
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Sure you can do that. You can also limit the battery current to 30 amps if your battery pack is filled with weak sauce. All kinds of compromises can be made. Not ideal.
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I understand a 200kv would be better on 10s ,…but limiting rpm on a 245kv on 10s to around 9000 rpm would keep things safe no?
In addition to what Chaka wrote, I would point out that you would also give up torque by staying with the higher kv motor. Remember, torque is inversely proportional to kv.
I understand that the torque is going to be lower, but I’m saying this so people don’t have to go out and buy new motors just because their motors’ kv are off by a little bit. The torque is going to be lower due to the erpm limit, but it is going to even out once the voltage goes down a little bit. In my case, I have 245kv at 10s, so the erpm limit is not going to be in effect that long anyway.
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Wow I’m really glad I read this! Was was just about to hook my new vesc from enertion (which I have waited forever for) to a tacon 160 245kv and a 12s lipo setup. I will totally be limiting to voltage to 8s instead of the full 12s.
I think you can still use the 12s setup if you want by limiting the erpm in the bldc tool. You just won’t have all of the power that 12s offer at full voltage, but you still have the benefit of the longer ride time from battery with higher voltage.
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Yup I will have to I guess. I originally set out to May my board a speed board but I guess 25 mph should be fine until I decide to get a different esc that can hand the erpm.
What motor or battery limit are yours set to or what’s considered safe? I’ve been running 60/60 and read 50 is the safe max. Is it solely heat dependent? Maybe 60 for shorter periods? Isn’t there a temp limit that would get tripped before it burned up. Don’t want to go down to 50
You missed a serious factor, the revolutions in kv is per V. Lets say you go with a 200 kv and 24 volts, that gives you 24 * 200 RPM on a fresh battery. What RPM will you have at 1/4 battery charge? You need motors to be around four times too fast and four times too powerful at the top of the battery life, in order to have the performance you want all the way through your battery use range.
You also need to consider your gear down ratio in the calculation.You need to consider the voltage top and bottom of battery life, gear down, kv, circumference of the wheel, desired top speed, and torque for hill climbing. I strongly suggest building a spreadsheet and plugging various numbers in.
What? Your battery voltage will only decrease slightly while discharging.
You typically go from 4.2V to something like 3.3V per cell while spending most time between 3.8 and 3.6V.
So no you do NOT need a motor that is 4 times the speed you actually want.
See for example a Lipo discharge curve:
Or did I misunderstand your post?
Thanks, you know your batteries way better than I do. But voltage is additive in series.
You are showing a 1.4 volt drop per cell. Assume six cells in series. For a top voltage of 22.2v, the last quarter starts with an 8.4 volt drop, 22.2 - 8.4 leaves 13.8.v So you would want about double not four times the motor.
You are correct, with that kind of battery performance my numbers were way off. I do appreciate the feedback. Great stuff. Now I need to refactor my build specs, again, tenth time is the charm.
No you still don’t understand. You will not have a 1.4V drop per cell. It will be 0.7V - from 4.2 to maybe 3.5V. Anything below 3.5V is territory you should not go to with Lipos. There is almost no energy left in your battery after 3.5V anyway (look at the graph). Also you will not start at 22.2V at 6S because you charged them to 6*4.2V = 25.2V. That means you will go from 25.2 at full charge to 21V. That is not much and the reason why most people just use the nominal voltage for their drive train calculations. You will spend most time around the nominal voltage of 3.7V - again look at the graph.
Thank you again, I think I need to meditate on what you just said. That is pure gold to me.