Update my single motor mboard to 2x HobbyKing motors?

[mjp8081]

I have an MBS board with some older e-Glide GI parts, basically:
36v LiFePo 20aH
wired gun controller
800w single motor mounted to a GI rear truck
(http://www.e-glide.com/electric-skateboards-store/electric-skateboards/gi-powerboard-detail)

I want to change to 2wd, and try to reuse the parts I have and keep the torque and speed--to something like this: https://www.youtube.com/watch?v=NzPsFwT2iDY

When I looked up these motors on HobbyKing (SK3 6374 - 192 kv), I am a little confused by the voltage and watt/amp rating. Are these a newer technology of motor that accepts a wider range of power?

Can I split the 36v output from the speed controller and use these kind of motors? How do I tell if I'm getting the equivalent of 2x 400w motors?

Also, by pushing forward on my trigger controlled SC it has "braking", by reversing the polarity a bit to slow down--does anyone know if these motors work with that functionality?

Thanks everybody! Also any links to custom parts makers like motor mounts would be appreciated.

 

[chuttney1]

When I looked up these motors on HobbyKing (SK3 6374 - 192 kv), I am a little confused by the voltage and watt/amp rating. Are these a newer technology of motor that accepts a wider range of power?

Don't worry to much about the voltage and watt/amp thing. The voltage and amp rating are what I believe is the maximum rating for the motor before you kill it. Watt is just how much power it produces. I'm coming to a hunch, the motor on your MBS board has two wires leading from it instead of the three you saw on Hobbyking. This type of motor is just better for the any type of electric skateboard since it has more torque. These are called brushless outrunner motor. The magnets are on the spinning part of the motor as opposed to the inrunner. As for accepting a wider range power, only till you reach the limits for voltage and amperage do you burn your motor...

Can I split the 36v output from the speed controller and use these kind of motors?

A fully charged lipo is at 4.2 Volts. Your pack is slightly passed the voltage of an 8s lipo. Just for comparisson. Okay to this question, by splitting, what do you mean? If its to have it connected to two speed controller from 1 pack, the capacity of the battery will limit you and I'm not sure how far you will go. Most RC speed controller will take only 6s lipo packs. The output from the controller will only work with one outrunner. I've read on a hobby forum connecting two brushless outrunner motor to one speed controller is disastrous. You will need one speed controller for each motor.

How do I tell if I'm getting the equivalent of 2x 400w motors?
Also, by pushing forward on my trigger controlled SC it has "braking", by reversing the polarity a bit to slow down--does anyone know if these motors work with that functionality?

The power rating of the SK3-192 kv is 2750 watts, or so I am to believe as stated on Hobbyking's website. The motor on your board is 800 watts. The SK3-192 is 3 of your 800 watt motors and more in one small package and weighs less than 3, 800 watt motors. You are going to get more horse power from the SK3-192 than the one on your MBS. The motors slow down by an eddy current being generated to work against the magnetic in the outrunner.

 

[mjp8081]

What an excellent reply chuttney Thank you--I have since found a couple articles about these RC setups/motors.

So these RC-hobby motor/SC e-MB setups seem like a HUGE tech step forward from mine.

Just to be clear:
So just 1 of the HobbyKing motors, assuming the power in is the same, will have 3x the torque and speed? Just from the smaller size I was assuming a big drop off in low-end, hill climbing power
Also, all these RC based boards use wireless throttles?
Whats the third wire on the RC motor for?
Where can I get a MBS truck motor mount?
Is my 36v 10aH LiFePo4 battery going to be too much for these 8S RC parts? I think my current SC has 2(4 wires) outputs for dual motors--one is just not being used.
So all the braking comes from reverse throttling(an eddy current being generated to work against the magnetic), like my current setup?

Thanks

 

[chuttney1]

The upgrades you are about to take are a step up from what you have, but better.

Just to be clear: So just 1 of the HobbyKing motors, assuming the power in is the same, will have 3x the torque and speed? Just from the smaller size I was assuming a big drop off in low-end, hill climbing power

I'm not really sure about having 3x the torque as the math may suggest as I have not seen anyone do an independent thorough testing similar to that found for automobiles on a dyno to quantify and verify the power and torque generated from the brushless outrunner as advertised. All I know is the brushless outrunner with a kv value less than 200 has very good amount of torque and the SK3 6374-192kv motor works. You can use two SK3-6374 motors for better hill climbing ability, but the board might be getting heavier. Having two 50mm motors are also fine, but the choice is yours. Regardless of any electrical motor, you will always get 100% torque from 0 rpm as the automotive world says. So you will have plenty of low-end torque, but this is depending on the speed controller to be able to deliver it correctly.

Also, all these RC based boards use wireless throttles?

Yes. I have seen electric boards in the past with wires from the controller and it doesn't look pleasing to the eye. The best controller to use is one that is small. You probably read from this forum using the Nyko Karma, a wii nunchuck, to control an eboard. Some the members here have used it, but there are still kinks to be ironed out.

Whats the third wire on the RC motor for?

Are you familiar with the concept of 3 phase motor? If not, here is a quick summary for electric motors. A standard Direct Current (DC) motor only has two wires, one for positive and negative and run using "carbon brushes" making contact with the "commutator" and two coils of wire are on per so many degrees of a revolution. Brushless motors do away with the carbon brushes, and use the basic principles of the electric and magnetic forces to rotate the motor much like a DC motor, but are essentially called 3 phase motors because three coil are turned on for so many degrees of revolution which is why the third wire is needed. The SK3-6374 motor is a 12 pole stator motor. Best analogy for a 3 phase motor in general is the AC induction motor because it works on the same principle as the brushless outrunner but uses no brushes or magnets. I cannot say brushless outrunner are AC motors as I am not sure if the electrical signal output from the speed controller to the motor is a sine wave or a square wave or a square wave moving in the same path of a sine wave.

Is my 36v 10aH LiFePo4 battery going to be too much for these 8S RC parts? I think my current SC has 2(4 wires) outputs for dual motors--one is just not being used.
So all the braking comes from reverse throttling(an eddy current being generated to work against the magnetic), like my current setup?

Just as said most RC speed controller (ESC) run a maximum of a 6s lipo or 25.2 Volts fully charged lipo. That's 4.2 V per cell at full charge. Your battery pack is over the max input voltage for an ESC made for a 6S lipo and 8S ESC, but not for 10S ESC. There are few ESCs made to run on 10S to 12S lipos, but expensive and not worth it if trying to keep your setup light, which is what you want. I have used a hobbywing XERUN 150 amp ESC with a max rated voltage for 6S lipo to build my first electric board, but it would act weird like the motor would do wheel "burnouts" from dead stop and going down hill had unresponsive throttle when you let go of the throttle. Your battery pack is much safe than lipos since the battery's chemistry is less prone to have a thermal runaway.
Yes, an eddy current is generated to work against the magnetic field and slow the motor down, but I do not think so for your current setup. I really do not know how DC motors brake. I am assuming you have a DC motor which would explain why it is large and needs a 36V 10 Ah pack as designed by e-glide. From the picture provided, it does not seem like a portion of the motors housing can spin as it does for an outrunner.

 

[torqueboards]

As far as EMTBs go, they aren't necessarily lightweight. Since it is bigger most people tend to go all out and go 2wd and 4wd's as standard. You don't see many if at all 1 wheel EMTB's.

Most of them do use SK3 6374-192kv and/or less kv (dual rear) motors to pop wheelies and get massive torque from the rear end.

Most if not everyone uses wireless controllers being the Wiiceiver Wii Nunchuck, HobbyKing GT2B, Quantum Pistol Grip. They each have their advantages/disadvantages. In the end it's personal preference.

8S will most likely be fine. Most people end up using 8S/10S/12S voltage.

You can run a higher voltage setup to accommodate for added power and/or run higher amps. Pull higher amps than 60 amps with 4 motors and/or use 2 motors and opt for higher voltage and run at lower amps. Either way they both cost a lot and there isn't much difference in price.

I prefer higher voltage.

 

[mjp8081]

Great community, thanks for all the feedback guys. Chuttney...you are awesome--your fingers must be sore

I rechecked my battery, it's actually a chinese Ping(well made though) 20Ah, 36v with BMS control board--36/4.2=8, so it must be an S8 right?

So I had a wireless board before, and I went wired because it throttles smoother--not an issue withe the RC throttles? No jumpy acceleration?

How does the throttle control 2 separate ESCs? Using same RC freq/channel?

So having a 36v S8 20aH battery, what kind of motor power specs should I look for? (Kv/Max Current(A)Max Voltage(V) Power(W) Max Current(A)

I looked around a bit, I cant seem to find someone selling MBS truck motor mounts--a lot of requests here on ESTF

Battery Specs (Do these apply to BOM RC motors?)
Specifications:
Suitable Wattage of Motor: up to 1200 Watt, 600-1000 Watt suggested
Applications: E-Bike, Electric Bike, E-Scooter, Electric Scooter
Voltage: 36 Volts (38.4 Volts Nominal)
Capacity: 20 Amp Hours
Dimension: 275*105*155 mm / 10.8*4.1*6 inches
Weight: 7.5 kg / 16.5 lbs
Charging Voltage: 44-45 Volts
Charging Current: <8 Amps (<15 Amps with High Rate BMS)
Rated Discharging Amperage: 20 Amps
Max Continuous Discharging Amperage: 40 Amps (60 Amps with High Rate BMS)
Maximum Discharging Current: 60 Amps

Sorry for all these replies and questions--I will figure it all out soon.

 

[mjp8081]

After reading some more and answering a lot of my own questions, I think I might be better off trying to sell my current board complete or as parts (the battery http://www.pingbattery.com/servlet/the-10/36V-20AH-LiFePO4-lithium/Detail alone was $500, and I have a feeling the SC is industrial and pricey) and use the proceeds to buy all these newer, better, WAY cheaper RC components. BTW my 800w motor is 3-wire (has the braking mode)

Now I need to go through the build posts and develop a parts list--it would be cool if all the "golden build" posts were in one place on the forum

Any suggestions for battery/charger setup? dual in series or single? Seems like dual 6s has more charger options

Its interesting how these 3 phase motors and controllers have a "transmission" to get torque to speed