from push scooter to EV: advice and comments welcome!

[Pouet]

Hi Tuurm

I did something similar to you last year and I think that it can be interesting that we share our work . Badfully, I had no extra time to use any software for drawing mechanical parts.

I did everything by hand with only a few tools.... : ( so sorry for the poor quality of this prototype....
I wanted to add a clutch... or something like a gearbox/demultiplier but can only fit a BMX freewheel.
In the pictures you will see a first "try" for the complete rear wheel system but there was some vibrations, so I switched to an other idea reusing and modifying existings escooter parts.

It's working very well but I wish I can replace all parts by parts crafted by a CNC and having a better transmission.

This is old pictures, just proto for riding test before to make a more finished product with a better motor mount, and all black paint.

More pic here : http://www.flickr.com/photos/73415413@N07

Pouet

 

[tuurb]

Hi pouet,

Your setup looks very nice.
In fact when I started on mine I thought to make it quite similar, also with the motor on that place!
I think the quality of your built looks good for a manually manufactured product!

What kind of motor, esc and batteries are you using? What gear ratio, speeds and range do you get?


I've also been thinking to add a diskbrake, but for the moment I could not find one small enough to fit my setup.
So for now I put the old brake back:


I'm finalizing the design and transforming my pieces to sheetmetal to make DXF's for the lasercutter.

Only I always find something I forgot, like:
-I need some static bearings because the rear fork hinges, so I need to make sure everything has the correct diameter...
I was thinking to use Igus bearings:

-I need to find somewhere these bolts in different lengths. Does somebody know the official name of these (in dutch?) or a DIN or EN number?


-I need to make sure I can find Inserts of the correct diameter to keep my rear sprocket stack together. -> found these @ fabory: http://www.fabory.be/nl/product/d7-cil-pen-tol-m6-2,5x10mm/39070025010.html

So lots of small things still to think of before I order all parts..

 

[tuurb]

Hey Tuur,

Looks good, although I'm not sure 3mm will be enough.

Why would you want to lasercut a custom pulley?
Have you thought about using a chain? You can just buy off the shelf sprockets and drill some holes to make it fit your rim.

About the batteries: are you talking about these?
http://www.aliexpress.com/item/For-sony-V3-18650-2250mah-3-7V-lithium-ion-rechargeable-battery-for-e-cigarette/1527982883.html
The discharge rate is only 5C which probably won't be enough. A good alternative for a Lipo is a LiFePo. They have a longer life in terms of number of charge cycles. Do you know what happened to your lipo's? At what voltage did you store them?

Btw, we have to go for a ride together when you're finished
Grts from your ex-colleague,i want to lase

Kris

Hi kris,

Just realized that i did not answer your post...

I really want to use a belt because of the noise a chain makes.
Because pulleys are not available in the size i want. I m going to try to lasercut and stack them.

Yes i want to use the sony v3 batteries. Because they are safe and vcan be charged without balancing.
I hope they ll be able to supply the current i need. But because of my 5p configuration i think it will be ok.

About the 3mm: i asked our mechanicals at work and they think it will hold. If not i'll add an extra plate on top of the rear fork to make an T profile for more strength.

We ll see!

 

[tuurb]

I just sent all my dxf's to a lasercutter.

Now I'm looking for a new spring for my longer wheel -fork, and I'm lost...

The old one is about 135mm long and the new about 206mm.
So the spring should be about 206/135 times stronger. That is about 1.53 times.

On the spring I find the text 900(lbs/in) which is about 157000 N/m.
Times 1.53 gives around 240000 N/m.

Now the problem is I can't find a spring this size with a spring constant of 150000 or 240000...
A spring constant is in N/m or kN/mm right?
All springs I find with about the same dimensions are about 1000 or 2000 weaker (so spring constant 100-250)

My guess is that the 900(lbs/in) on the spring of decathlon is wrong...

Anybody?

Thanks in advance!

 

[beto_pty]

Anybody know where I can get some thumb throttles? I'd like to tackle one of these kick scooters using all my left over parts/batteries gears from my skateboard build.. however im stuck at how to control the speed. A servo master looks incredibly awkward and basically uncool.. any suggestions? Ive googled 5v thumb throttles any other suggestions? or in its absence a 5v twist throttle i guess would do..

I'm guessing that the pot has to be 5kohms? to work with my airplane 6s ESC which i ditched because it had no brake.... hey quit rolling your eyes.. i hadnt heard of ES back then...

 

[Rutiger]

Like this: http://em3ev.com/store/index.php?route=product/product&path=41&product_id=143 ?

 

[beto_pty]

Cool thanks for the tip..
.. I'd connect this directly to my esc... or would i have to tear apart my remote controller, hijack a 3 pin connection, plug this controller there and use the remote/receiver combo..
Also any other options in the US? shipping from china to Panama is quite an ordeal i'd like to avoid if at all possible

 

[tuurb]

I'll be using also a thumb throttle like this.

Anyody an idea about the spring?
I'm taking it to work and will put it under our press and just measure the spring constant myself.
My guess now is that the 900lbs/inch is the spring and the red rubber part together...

 

[beto_pty]

Hi turb
Please repost your thumb throttle idea.. I don't think it uploaded correctly
Thanks

 

[tuurb]

hi beto,

I meant that I'll also use a similar thumb throttle.
I'll use it together with a servo tester as described in http://endless-sphere.com/forums/viewtopic.php?f=28&t=12196&p=873024&hilit=+throttle+tester+thumb+servo#p873024

 

[beto_pty]

OK.. I understand.
It works well but it is cumbersome to work while riding a speeder.. also the range of motion is over 90 degrees.. more like 180 degrees so you go from full brake to full speed with neutral in between...
If you have any ideas how to actually mount it and work it please share. That is the only missing part to my wifey-s scooter

 

[tuurb]

Hi,

I haven't been able to actually mount everything yet because I'm waiting for my recently ordered solder suction tool...

I'm hoping the 150A HK esc I'm using can be programmed to "listen" to the signal the servo tester will send.

If not I'll maybe use an arduino nano to translate the 1-4V signal into the correct servo signal.
You can find info on the arduino website. translating a voltage into a servo signal is one of the examples available in the arduino program tool.
Quite easy to adapt this so it will work with a hall throttle. An arduino nano v3.0 is only 6$ on ebay.com (shipping incl!)

A more expensive but simplier option is to buy the hall throttle interface of alienpowersystems.com

I'll post some more info when I was able to test something.

Regards,

 

[tuurb]

Just got some of the mechanical parts!
The 90T 5m sprocket turned out quite good.


Just waiting for 3 more parts to be bended and welded together.

Also made a functional hall throttle to esc signal convertor with an arduino nano. Even made a calibration procedure to really use the min and max value of the hall sensor and not just assume the voltage will be 1-4V. arduino programming is quite easy with all the examples and libraries available!

 

[Murfix]

Congrats, those pieces look awesome, especially the large pulley!

Where's that Hall sensor you're talking about? Is it used to measure the position of the thumb throttle?

About the spring: maybe it's worth testing to see if you can use the same spring? By changing the standard tension on the spring, you can adapt it to your longer rear wheel 'arm'? By standard tension, I mean you can change the length of the spring in rest position (make it shorter) so it stores more energy.

If you google "Bajaboard", they use adaptable dampers.

Give me a call when you're ready, we should take a ride together

 

[tuurb]

Hi,

I'm using a hall thumb throttle:


to translate the 1-4V that come out of the hall throttle I bought an arduino nano and programmed it.
This was very easy I must say. I have no experience whatsoever with programming but just opened some of the examples and adapted them to my needs.

I'm still waiting for this last part to be bended and welded together. After that I only need to put everything together.
I'll be using a big Lipo that I have laying around. After I'm sure all works good I'm going to order a bunch of 18650 samsung 25R cells or sony vtc5's...

I'll definitely will give a call when I'm ready Murfix!

 

[Dauntless]

Just so you know, the California DMV uses the term "Footboard Scooter," meaning intended that you stand. I suppose if you have a seat it can still be a footboard scooter as long as the serious footboard is there. The Currie scooters, for example.

I for one would always prefer a chain.

 

[tuurb]

Hi,

Jeah here in Belgium you need an insurance if you go faster than 12km/hr with a motor. Also your vehicle needs to have a unique chassis number etc.
When you go faster than 25km/hr you need a helmet and driving license.
Guess I'll be driving around illegal...

Just received the bended parts:
battery cover:


and I quickly put together the rear bridge with tape. Now I'm hoping my colleague can weld these parts together this weekend!

 

[tuurb]

I'm driving around now with the scooter but it seems that the motor cannot deliver enough torque to accelerate.
When driving at low speeds and accelerating suddenly the motor 'screeches' and does not deliver any power to the wheel anymore...

I thought this would be that I'm asking to much torque of the motor that I power with a hk150 esc and 8000mah 6s batteries, but then I see others that achieve better results with a higher kv motor and a gear ratio that is worse then my 25/90.

So i tried with a 19/90 gear ratio and an alien 8s esc and it is better, but still i have to take it gentle on the throttle or the motor loses sync...

anybody experience with this? What am I doing wrong? Could it be that my sk3 6364 213kv motor is a bit broken?

thanks,

Tuur

 

[ipcalit]

I guess you're getting the motor out of sync. Adding some hall sensors inside should help. Just my 0.02c.

 

[Armon]

Hi tuurb,

do you have any update on your project? Were you able to solve the motor sync issue?

 

[tuurb]

Hi,

the setup seemed to work better on 6s than 5s batteries.
therefore i tried with an alien 8s esc and 8s batteries and with another gear ratio.
this gave similar topspeed but much much better acceleration before loosing sync. now it only looses sync when you ask for really high accelerations!

Because I really want the max acceleration this motor can deliver I'm now going to try with another esc and 10s batteries. I hope the acceleration will keep going up

 

[tuurb]

Hello,

I decided to sell the scooter and all the parts.
I recently bought a house and I do not have the time to finish the project.

Setup drives but should be finetuned. Accelerating hard is an issue.

Setup now:

Sk3 6065 motor

1x 5s 8aH battery zippy
2x 2s 8aH battery zippy
1x 3s 8aH battery zippy

Vesc

Arduino nano to translate thumb throttle to ppm signal

Feel free to make an offer.

Thanks