Choosing the right motor kv for the VESC

I made some today, can be shipped on Monday.

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How much ? And from where?

@elkick is the owner of www.esk8.de in Germany.

O ok thanks

Hi, I am a new builder/user to this forum and I am very excited to be getting into such a fun project. I live in SF where there are plenty of hills and I weigh about 145-150 lbs and was wondering what components I needed. I will be running a single motor with the VESC, with 2x 4s 5000mah 20c Lipo in series. I bought DIYelectricskateboard’s 16T/36T motor mount kit as well. SO what I don’t know is what motor I need (been told 230kv is good) and does any suggestions for a comparable but cheaper alternative to DIYelectricskateboard’s on/off antispark switch. Thanks to anyone who replies!

@SFrider http://www.electric-skateboard.builders/t/how-to-anti-spark-xt-90-loop-key/204

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@SFrider - yeah the xt-90 anti-spark loop key is the uber simplest. Alternatively you can make your own anti-spark switch. If you want one, i have only a couple left. Feel free to PM me if interested. Here’s the ES thread in their sale section.

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So above 8570 RPM is less efficient (and prone to failure). but I don’t understand if it’s more efficient to be closer to the limit from below, VESC wise. For example, Is 8s 245kv (8,232 RPM) more efficient than 6s 245kv (6,174 RPM)? I’m not talking about motor efficiency. Thanks.

@SFRider - We have 6355 170/190kv in the works for people who use higher voltage ranges. 5055 280KV/190KV options as well.

To my understanding the erpm of 8s on a 245kv motor is 50764 erpm with 3.7 volts cell (29.62457=50764) and 57624 rpm with 4.2 volts cells (33.62457=57624). So even if the cells were fully charged it is below 60k erpm so it is completely safe to run a 8s 245kv setup with the vesc.

@jrpwit Thanks for helping, but I meant to ask Is much lower erpm than the limit is less efficient than closer to the limit?. Thanks. well my syntax sucks.

Anything under the 60,000 should be good. I would think that being close to 60k would be less efficient but anything under 60k will work fine.

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I bought one on these Trackstar motor analyzers and tested it on a couple motors: TB’s 6355 230kv Result 197kv Alien 6355 190kv Result 172kv Both motors had results lower than there rating. You would think that this analyzer could calculate KV at any rpm but it doesn’t seem to work that way. As I turned the knob and increased rpm, the KV went higher. Because the rpm is limited to 2s voltage which is the max this analyzer can handle, I believe that it is not giving a true analysis of either motor. Bottom line, this analyzer was a waste of money.

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I used the VESC and calculated kV using erpm, duty cycle, and voltage measurements during bench testing and came out to 197kv on a 200kv motor with chaka’s help. You could try that.

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My TB 230kv motor is actually 198kv according to the VESC so that seems pretty accurate to me

Referring to the track star analyzer, why would the KV increase as the rpm is ramped up ? And it stops at 197 at 8 volts. What would it read if I could run it at 50v?

Good point

60k is what I’m shooting for. I’m gonna go with 10s and 190kv when my Vesc’s arrive.

Longhairboy has used 12s 190kv and hasnt had a problem or maybe he has and I just haven’t seen it yet

I think Photorph said he face planted on his LHB due to some VESC issue.

I seem to recall that anyway.