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120kv, 1.5kW brushless motor for a single motor setup


#1

Hello guys, I am a newbie in e-skating and actually also in skating world. Nevertheless I am to building an e-longboard. I need an advice regarding a motor. I am proposed the brushless D-Power BL 6362/120 motor, I guess some kind of German brand, I am located in Berlin. Basically specs are the following:

  • dimensions: 62 x 60 mm
  • weight 550g
  • 120 kv
  • 1500 W
  • battery support up to 12s
  • price: 40 euros = 46 USD

I wonder if this motor is ok for my setup? I’ve learnt that the less kv i have, the higher torque and lower max speed I get. However when I make some calcs with a standard variables like 15 teeth pinion and 36 teeth spur, 83 mm wheels and 24V battery I get 19 km/h as a max speed. I wonder if that’s acceptable (pls keep in mind I have no clue how fast it means since I tried skate/longboarding 3-4 times).

The items I already have in a setup are:

  • 83mm abec wheels
  • 27 cm long, 9 mm wide, pitch 5 belt

I also understand that I can theoretically increase max speed by using different spurs and pinions however not sure that the length of my belt (27 cm) allows that.

What would be a difference if I use for example this: http://alienpowersystem.com/shop/brushless-motors/alien-5065-fr-outrunner-brushless-motor-270kv-2000w/
or this motor: RC C6364 245kv

thanks in advance!


#2

Hey bro…

Let’s start here…use a 70-75 efficiency :metal:t2:


#3

Hi, Michael! Thanks a lot. That’s what I get with the most standard numbers and 120kv:

Does it make sense? I mean I read couple of sources stating “buy the lowest kv motor you can since max speed isn’t that important as torque”. So I would assume I would get a lot of torque, in other words I would be accelelrating very fast with 120kv motor, however in order to get higher speed (than 17 km/h) I’ll have to choose different pulleys or higher voltage battery, right? Is there any other principal advantage of having a high torque motor except getting faster acceleration? E.g. how would this motor behave when it needs to go uphill?


#4

Yes, more torque = more power to go uphill too.
The problem is that with 17km/h max speed you may get bored too quickly.
Almost everyone will suggest you a motor around 190-200kv or getting a 12S battery if your kvs are that low with that motor.
Also your motor power should be probably > 2000w if you want enough power, also it depends if you’re hevvy or not, and how high are the hills you want to go onto, if you’re ~60kg and you keep high torque then it will be ok.

If you go with the second instead you will have more power (2kw instead of 1.5kw) but then you’ll may need to stick with a 6S setup because a 12S the torque may be a bit too low? Also the motor is small (50x65mm) so it could overheat.

Many people from this forum will suggest you the SK3 192kv from hobbyking:
http://www.hobbyking.com/hobbyking/store/__672__663__Electric_Motors-63mm.html or the rspec+ from enertion 6372 if you have the $$

post how much you weigh and if you need to go up big hills


#5

How much do you weigh?

I would say that if you weigh less than 150kg then 120kv is waaay too low if you only plan on running 6s. When I started eboarding I had little experience with skate/longboarding in general and my board could do about 25 km/h and after just a few weeks I started gaining more confidence and yearning for more speed. 13km/h will feel like a toy after a very short time.

If you weigh 70-80 kg or less then I’d recommend a motor with around 250-280 kv. It will still give you plenty of torque and a better top speed with those gears.

Of course you could also run your motor in a 12s config for more top speed + more torque. Low kv is generally good, but you shouldn’t go too low.


#6

am I wrong or if you go from 6S to 12S the torque actually decreases because of the RPM increase?

Power (watts) = Volts * Amps * motor efficiency
Torque = (Power60)/(2pi*RPM)

The RPM with higher voltage increases so the torque lowers, isn’t it?


#7

As far as my first hand experience and knowledge goes, going from 6s to 12s theoretically means double up on torque and max speed and it halves the used amps.

I don’t know about the fancy mathematical formulas tho :sweat_smile::sweat_smile:


#8

I don’t know either :sweat_smile::sweat_smile:, I just found them online and now I’m curious to know if really everything is doubled so there’s basically no point of running on low voltage, if somebody can explain :smiley:


#9

The lowest I’m going is 149kv with the Turnigy Sk…but I’ll use 12s with a 16/36


#10

Hey guys, thx a lot for all the answers. I am about 72-75 kg, hills would be an exception rather than EV every day practice, but nevertheless good to be able to climb some of them I guess. Generally not steep.


#11

I am located in germany. I asked about this 120 motor only bcoz it’s super affordable since it s private sale however motor is new and I can get it quickly. The next cheapest motor is 62-70 euros. Anyways none of famous hobbyking turnigies are in stock. Another option is probably this: http://m.ebay.de/itm/RC-C6364-245kv-Brushless-Outrunner-Motor-/152069194891?_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20150519202354%26meid%3D498325e53a6b4c559ea96df5b8b66b19%26pid%3D100408%26rk%3D4%26rkt%3D21%26sd%3D161988186137&_trksid=p2056116.c100408.m2460.

Wow sorry for this… I am typing from my mobile! :slight_smile: or motors from aliendrive. They seem to have couple in stock. I found one from aliexpress ad well but I am kinda reluctant to trust Chinese also those customs payments I guess.


#12

Bro…spend your good Euros on something else…it may be a great deal…but it’s less than ideal for what you want to use it for…

But move to a kv Range I would say…149 low and at the most 270kv

There are plenty of diffrent motors and price points


#13

When I look at these formulas, it seems that torque wont change, bcoz RPM = KV * Voltage and power = current * voltage, if we fit those two equations in the torque formule, the those voltages would just “remove” each other - sorry I don’t know the correct English word, hope you get what I mean.

May be I am wrong, just my opinion.


#14

My problem is that I cant find the online sources to order those motors… I need delivery to Berlin.


#15

I hear you mate…we don’t have such problems here in the US…


#16

Hey im from germany too.
You could visit the german forum elektro-skateboard.de . There are also a few people from berlin and maybe someone is selling a motor in the market.


#17

Had a recent email conversation with Bruno from alien drive systems and he assures me all his motors are in stock even though it doesn’t show this on the website.
Could be worth dropping him an email?


#18

Thank you for valuable advice!


#19

Thanks, i am familir with this forum as well! :slight_smile: I actually started the similar topic there and got some good input! Shortly: seems like motor should be ok if I use a high voltage battery like 12s. But I still wanna look at the cost factor. Here is the thread:

http://www.elektro-skateboard.de/forum/szene-talk-63/120kv-1-5kw-motor-ok-fuer-single-motor-setup-5430.php

There is some English at the end - guys were tired of my broken German… :slight_smile:


#20

I did a lot of reading and I can’t figure out what gearing to use… I would like to have about 30 km/h as top speed, and decent amount of torque, can you help me? Thanks