Lower kv vs higher kv?

Lightweight / Folding / Portable EVs - seats optional
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mkoch820   100 µW

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Lower kv vs higher kv?

Post by mkoch820 » May 23 2016 11:19am

Hi!
I'm trying to find the best motour for my needs... As you all might be aware of, Turnigy SK3 motours are out of stock in all warehouses at HK :/
The famous budget option, SK3 5055 280kv is unavailable, but there's this one, still available in the UK: SK3 - 6374-168kv
http://www.hobbyking.com/hobbyking/stor ... ouse_.html
My question is, can I use this one as a substitution? Based on CalcRC, using 24T pinion and 36T spur with the 168kv motor, would give me about the same top speed as the 280kv motour with 14T pinion and 36T spur.
My setup is going to be a single motour version on 6s (2x8000mAh 3S), 70mm wheels. http://www.decathlon.fr/longboard-bambo ... 30718.html
Will i get similar results in terms of torque and range?
I appreciate every feedback! :)

EDIT: Also on the product page of the 168kv motour, it says "Voltage: 12S Lipoly". Does that mean that it can be used ONLY on 12S, or is that the maximum?

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Vanarian   10 kW

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Location: France!

Re: Lower kv vs higher kv?

Post by Vanarian » May 23 2016 3:51pm

Welcome to ES! Are you french? :D

If you run only 6S I reckon you will prefer the higher KV version. But now this depends also of your ESC choice. You need to check if you can fit your motors on the Oxelo's trucks, unless you have access to a dremel?

Good luck on your build ;) you should make a more precise title for your thread too.
-+AT-One project : electric inline skates - no remote, hub motors, one frame for various wheel sizes & quasi-universal boot mount

Rollo Ergo Sum!

mkoch820   100 µW

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Re: Lower kv vs higher kv?

Post by mkoch820 » May 23 2016 5:16pm

I'm European, but not French (hungarian). I struggle with finding the suitable motor, since I don't want to order from America, paying for the duties and shipping would make my budget build not so budget. .If someone could recommend a reasonably priced EU webshop for the electrical parts, i would be grateful!
The oxelo has trucks similar to Paris trucks, but I also have Dremel and an angle grinder, so modifications shouldn't be an issue.
If that fails, choosing the right gear ratio would give me the same top speed, would the motor work less efficiently?
Thank you

WeeChumlee   1 kW

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Re: Lower kv vs higher kv?

Post by WeeChumlee » May 24 2016 2:36am

Hi mkoch820

Motors, in the UK, are available here:
http://alienpowersystem.com/product-cat ... tors/63mm/

I personally have one of these on one board and can say it pulls like a train.
http://alienpowersystem.com/shop/brushl ... 0kv-3200w/

I hope that helps.

chuttney1   100 W

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Re: Lower kv vs higher kv?

Post by chuttney1 » May 24 2016 3:35am

This topic was discussed before here, but I am not sure if you are new here or came back after a hiatus. So I'll put a link to one of the more knowledgeable members here who did testing and found a conclusion.

Link about Kv:
http://vedder.se/2014/10/chosing-the-ri ... kateboard/.

A comment about this article. The Kv rating was tailored specifically to the VESC to run at a specific RPM range for greatest efficiency. That being said, the general rule of having a lower Kv such as 192Kv is partially preferably because of the higher torque need to move you. It is okay to have a high Kv such as 320Kv, but not 1000Kv becuase of a high gearing reduction. You must take into consideration what gearing ratio to have between acceleration/torque and top speed depending on the terrain you wish to ride on.

mkoch820   100 µW

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Re: Lower kv vs higher kv?

Post by mkoch820 » May 24 2016 9:16am

Thanks, for both of you, that guide was exactly what I needed.
I'm completely new here, I only have experience with rc planes and multirotors, gear ratio is something, I haven't had to bother with before.
That 6374 170kv alien motor seems to be perfect, I'm definitely going for it! To futureproof my build, I decided to get an 8S capable ESC, like this one:
http://www.hobbyking.com/hobbyking/stor ... ouse_.html
Since all these HV ESCs seem to be OPTOs, I'm going to need a BEC. The only thing that requires the 5V of the BEC is the transmitter, so I should be able to get away with a cheaper one, right?
http://www.hobbyking.com/hobbyking/stor ... ouse_.html
I really appreciate your patience, and helpfulness!

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mccloed   100 W

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Re: Lower kv vs higher kv?

Post by mccloed » May 24 2016 4:18pm

Welcome @mkoch820, I would advise against that particular ESC. I have had two of those. One went up in smoke and the other has to be configured every time you turn it on. If you still decide to go with that ESC someone here figured out that it does actually have a built in BEC.

mkoch820   100 µW

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Re: Lower kv vs higher kv?

Post by mkoch820 » May 24 2016 4:48pm

mccloed wrote:Welcome @mkoch820, I would advise against that particular ESC. I have had two of those. One went up in smoke and the other has to be configured every time you turn it on. If you still decide to go with that ESC someone here figured out that it does actually have a built in BEC.
Oh... Thank you! Can you suggest something instead? Preferably car ESC, so it can do reverse

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