Trampa EMTB Dual Motor "No-Wind"

N

nowind

100 W
Joined
Nov 9, 2014
Messages
160
Hi Everyone,

my name is Jenso from Germany.

I´m a Kite and Kitelandboarder, have some Rc Knowledge and working as a Millingmachineoperator.

So i decidet to build up an EMTB based on my excisting Trampa Kite board.

Started with one Motor Rearleft, then a second on diagonal Frontright, and at the moment Dualrear Setup.

I think its most fun with the rear drive, drifting and carving and so on

Using parts from RC i had still left from my RcCars :
Hobbywing 150A ESC
Spektrum DX3R
Hyperion Duo Charger

New parts are :
2X SK3 6374 168kV
6S2P 5800mAh ZippyCompact

Using a 4mm Chaindrive with 6mm pitch.
The gear Ratio is 4.15

Milled Aluminium Motor mounts from 10mm 7075-T6

Tracked the Speed via mobilephone gps about 30kmh, more then enough for offroad i think.
Set the Timing from the ESC to the max, now its really nice directly driveable.
For sure from deadend you will notice a bit cogging but not much, see the video.

Not really sure if it will being better with shorter gear ratio from 5:1 or 6:1, maybe its more a "sensorless motor" problem. What do you think?

I get really into the EMTB Stuff and i LOVE IT

THX to the ES Forum, many great builds and loads of knowledge up here!

Best Regards
Jenso

https://www.youtube.com/watch?v=zjZafqjvnME&feature=youtu.be













 
Great mounts, nice and simple! When you go back to dual rear drive, link them with a rod for stiffness. I don't know if it could actually be a problem, but the cutouts in your mounts will decrease the strenght and only offer very little weightsaving, so when not linked, like in dual diagonal drive, they mitght bend over time. Or they might not :) I just know that beetbocks removed those cutouts from his kit to increase durability (but his plate is only 6mm thick).

Good choice on the chain, I think I got the same ones!
 
Very well made.

Helps to have access to machining equipment
 
ThX man, glad you like it.

Yes Life is easier with a cnc (-;

Have the same thought about a rod between the motormounts.

Made one yesterday, maybe will mount two more of these to ad more strenght

Here its mounted:



 
Nice one! Will aluminum generate eddy currents? I have n clue, but I always thought you would need a conductive material for that, like hendo using copper plates.
 
Well, I was right then: I have no clue. Was just wondering why hendo uses copper plates then.
 
Hey man,

wow ok thats new to me thats aluminium have an influence on the magnetic field of the motor.

I thought the motormounts itself are full aluminium and attached direct to the motor so i dont mind.

Now i´m really confused, because i have had a short ride today and must stop after 15minutes cause its started raining.
I charged the batteries and wondered that only 30% left, normaly after 15minutes there are at least 50-55% capacity left.

I thought it was in cause of soft ground and much full throttle.... mmmh do you really think it caused by the rod?
I measured 7mm space between motor and rod, is it too near?
Made a second rod today which i wanna mount under the other rod, now i´m not sure !!!
 
Really nice build!! I love the trampa boards from the start and the mounts look amazing.

Got a couple of qu:

Is your top speed of 30kmh measured on road or off-road.
How much does your board weight?
I though or outrunners the timing is suppose to be low not high?
Are you useing the 6s2p 5800mah for both motors or is that for each motor?
How many ESCs are you useing?

Lol that's a lot of qu!!!! Amazing build!! EMTB is the way to go!
 
As long as the metal isn't in the magnetic field it doesn't matter. it's only if it ends up there that it makes a difference, and even then only if it's moving within the field (or the field is moving past it). If you want to see, you could use an IR imager, and then run the unit for a while, and see what gets warm.

You could also use an IR thermometer, tha tjust tells you the temperature fo the spot you point it at, and carefully move it around to see what parts are at what temperatures.

If there is any warmth generated on the questioned areas, and they are not actively being warmed by hot air from teh motor, or radiated heat, then it would be induced heat by eddy currents.

You could also probalby measure the magnetic field strengths and see about how far it goes from the motor, and if it intersects the areas, but I dunno that would be worth the effort of figuring out how to do it and setting it up.


Basically any metal moving isnide a magnetic field will create a current within the metal. That's how a generator (or regen braking) works. The coils cut thru the magnet fields, and generate a current in the wire.

You can even take a powerful enough magnet, and move it around in circles on a piece of metal (aluminum, etc) and heat the metal up by the induced currents, but doing it by hand with the magnets you'd typically have laying around probably won't be that noticeable.
 
BShady said:
Really nice build!! I love the trampa boards from the start and the mounts look amazing.

Got a couple of qu:

Is your top speed of 30kmh measured on road or off-road.
How much does your board weight?
I though or outrunners the timing is suppose to be low not high?
Are you useing the 6s2p 5800mah for both motors or is that for each motor?
How many ESCs are you useing?

Lol that's a lot of qu!!!! Amazing build!! EMTB is the way to go!
Click to expand...

Hi BShady
I meassured it via Handy GPS on a gravel path. But that was one of the first test with only one motor.

Sorry no balance here i dont know, will tell you soon.

My knowledge is that this big outrunners used with high timing. Maybe some experts up in here can tell us the truth (-;
First runs i used lowest timing and if i hit the trigger hard the motors lost it sync(cogging), after setting max timing its much better, the driving is more direct. It felts the motors have 30% more power with full timing. The Temperature increase about 10 degrees.

I am using 6S2P with overall 11600mAh for both motors, runtime normally at least 30 minutes if you go hard on triggger.

I am using two Hobbywing 150A ESC connected via Y-Harness
Hope that helps

amberwolf said:
As long as the metal isn't in the magnetic field it doesn't matter. it's only if it ends up there that it makes a difference, and even then only if it's moving within the field (or the field is moving past it). If you want to see, you could use an IR imager, and then run the unit for a while, and see what gets warm.

You could also use an IR thermometer, tha tjust tells you the temperature fo the spot you point it at, and carefully move it around to see what parts are at what temperatures.

If there is any warmth generated on the questioned areas, and they are not actively being warmed by hot air from teh motor, or radiated heat, then it would be induced heat by eddy currents.

You could also probalby measure the magnetic field strengths and see about how far it goes from the motor, and if it intersects the areas, but I dunno that would be worth the effort of figuring out how to do it and setting it up.


Basically any metal moving isnide a magnetic field will create a current within the metal. That's how a generator (or regen braking) works. The coils cut thru the magnet fields, and generate a current in the wire.

You can even take a powerful enough magnet, and move it around in circles on a piece of metal (aluminum, etc) and heat the metal up by the induced currents, but doing it by hand with the magnets you'd typically have laying around probably won't be that noticeable.
Click to expand...

Hey Amberwolf,

thx for elaborate answer. It make sense. Unfortunately i have no IR device at the moment, i lost it on weekend during riding the EMTB (-;
I need to buy a new one. To detect if there is a influence i will do the following:

I will do testruns of 10 minutes today with nearly equal terms and conditions. First one with the Rod, second one without, maybe a third one with the second Rod i milled last night. I´m really excited what will happen.

If i get it right my logic tells me that the amount of eddy current depends on the mass of the metal material in the magnetic field of the rotor?
So i could think about to machine the braces(rod) much lighter (-; isnt it ?
Better would be using more distance for the rods, but that means new motormounts...

But first i will test it like i described.
will report...

Have a nice day
 
How tight do you make your bindings?
Mine are pretty loose but not sure if I should make them tighter.
 
BShady said:
How tight do you make your bindings?
Mine are pretty loose but not sure if I should make them tighter.
Click to expand...

Have a look here, cant explain better :
https://www.youtube.com/watch?v=ObNSURYIj9E
 
I tryed to evaluate today if there are any side effects from my rods like eddy currents or not.

I run three times the same track (same distance) in the same time (10minutes) and measured the left capacity of the batterie.

First run without any braces and second run with two of my rods. It was exacty the same amount left in the batteries.

But by both runs i need more then the last times.
So i started to check the board and recognized that one tire has really low preasure, insteads of 50PSi less then 20PSI.
After refill all tires made the third run and had left 10% more capacity in the batterie. So guys check your pressure,
Highspeed loged via GPS increases about 3kmh .... now 37kmh.

Decided to machine the Rods again to remove all material which is not necessary.
Now they look a bit more badass and i hope any left eddycurrents are minimized.
Hope they are no secret eddy currents wich destroy my motors!







Also rebuild the both driven Hubs with wider spacer to get more clearence between the sprocket and the tire.
Because i recogniced on the inner wall of the tire traces from the chain.
Must using longer screws now too.
Inox M4x60MM Countersunk with 12mm spacers give me 3mm more clearence now.





Greetz
 
Good weather last days, so got some new video footage.

Have a look on my youtube channel :

https://www.youtube.com/watch?v=9Xt_FsBXRcE&feature=youtu.be
 
mortifiedMORTY said:
It's definitely fast! this is awesome
Click to expand...

Yes it is, 35kmh not sounds much, but it felts much faster standing on the board!

BShady said:
Dude insane carving???!!!! How do you carve that good?
Click to expand...

Thx BShady, i´m driving everyday since 3 weeks (-;
Also using the softest Trampa Dampas (yellow ones) this helps too.
 
Man that Trampa Board looks nice.. Looks way lighter than my heavy Vault one. Not to mention the great motor mounts.
 
+1 benj :wink:
Would you please also tell us some electrical consumption numbers on flat at a given average speed ?
We aren't many to sustain 35+ kph average speed, so if you could have a try in this range, that would be great :twisted: :twisted:

(it's to feed our "battery range" topic :wink: )
 
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