from push scooter to EV: advice and comments welcome!

Hi!

Very nice forum, im very happy to find people with the same interests as me...

I'm planning to convert a push go ped inta an electrical one, it 'll be my first EV so i could use some advice...
I bought a 'Town7' go-ped in decathlon (a big sports-shop in europe) with 200mm wheels and suspension (see picture)
It weighs 5,6kg and I hope to keep the weight with batteries under 10kg...

The rear fork of the go-ped is detachable so i was planning to make a whole new one with space and holes on it for my brushless dc motor...
(alltough I'm not yet sure where I am going to mount the motor (at the rear end of the wheel or on top of it...)
I plan on using a turnigy TR 80-85 or a HXT 63-74 200kv Brushless Outrunner and a car ESC to be able to brake on the motor.

I also plan to add hall sensors at the outside of the motor, I'll be 3d printing a bracket to mount these on the motor.
It is correct that the current draw of the motor will decreas so I'll have a bigger radius right?


So here my questions:

Should i use a chain or a belt? and what are the significant differences? I was thinking to use a belt because i think it will be less noisy...

How good can you brake with a brushless dc motor? (for the moment i wasn't planning to add any extra brakes, the go-ped has allready a 'push-brake' on the rear wheel...)

Do i have to shield the brushless outrunner for rain or not?

How can I correctly calculate rpm's to calculate a gear ratio? I understand the unit Kv but i can believe the motor slows down when it has to push a go ped with a 70kg person on it...

What type of batteries should i choose? I was planning to use lifepo because i read they are safer and last longer...
Will a discharge rate of 30C be enough for my application?



Thanks in advance for the advice!

Greets, Tuur (from Belgium)

the oxelo town7 looks very cool...
i would like to test one out, the ride might be too rough for my taste, (i ride on 10" air tires)

someone here built a non suspension version...
http://endless-sphere.com/forums/viewtopic.php?f=35&t=29136&p=420676&hilit=oxelo#p420208

btw, you should use the term 'stand up or push scooter', goped is a brand name...

thanks for the reply,

ok so stand up scooter it is

What kind of batteries are you using on your scooter? Do you think that 30C decharge rate could be enough to power the ESC and motor with 5s lipo batteries?

Thanks, Tuur

Hiya Tuur

btw, you should use the term 'stand up or push scooter', goped is a brand name...

Click to expand...

I'll suggest "foot bike" also... Euro languages use "trotineta" and "trottinette".. Then there's "Potkulauta" (Finnish), "Kolobezka" (Czech), "Tretroller" (German), "Sparkcykel" (Swedish)... well, a long list

Check out IKSA:
http://www.iksaworld.com/

But in English language in Europe "foot bike" and "kick bike" appear a lot. Have to say though, as an english-speaker myself interested in electric "scooters" that the Swedish "Sparkcykel" holds a certain appeal!

Really nice-looking scooter that Town7...

The problem might be gearing down the high RPMs (and lower/safer amps) that the RC motors and ESCs prefer. High torque/amps are the ESC killers.

I'd consider mounting the motor on the down-tube with a double-reduction driving the *front* wheel...

Lock

ps... Can we add a name for "scooter" in Walloon?

sk8norcal said:

btw, you should use the term 'stand up or push scooter', goped is a brand name...

Click to expand...

yes. the word goped confused me because i thought it was a goped. own a couple of ACTUAL gopeds, and when people refer to goped sometimes, they mean every single motorized scooter they see out there which is not true since goped is an actual brand name.

but back on topic,

looks like a great platform to work with. those 200mm wheels look like they can handle a lot especially in the urban environment. i have a 50-56 series rc motor and i think its suffice for me on my goped, and its a friction drive . a 63-74 might be a good choice to go with, but who can say no to more power with a 80-85 motor?

def215 said:

a 63-74 might be a good choice to go with, but who can say no to more power with a 80-85 motor?

Click to expand...

On my scooter a 63-74 was more than enough, I only started burning them up when I put them on my bike. I'm pretty sure that with an 80-85 you would lift off from the ground and never be heard from again...

I've been thinking as well to mount the motor on the front wheel but my first idea was to keep the scooter/go-ped/standup scooter... as original and clean as possible.

so a 63-74 turnigy it will be,( but not for soon because they are allready out of stock at hobbyking.)

I've been thinking and now prefer a chain because of its smaller sprochetsize, (i don't want a very wide rear fork)

Nobody with advice about batteries? I'm not certain 30c wil be enough with a 5s2p or 6s2p pack...

thanks, Tuur

what size pack will you be using?

what i have is a 6ah 22.2v pack(3000mah 11.1v lipo packs in 2s2p). its rated at 20c continuous discharge(120amps). the max amp draw on my setup ive ever seen is ~70 amps and goes down as im up at speed.

i think itll depend how big the pack is.

I was thinking to buy 2 Turnigy 4500mAh 6S2P 30C LiFePo4 Pack's...
I'd rather buy LIFEPO4 because i read these are safer then lipo...i want to be able to leave the batteries unattended when charging them.
Now i only need a bit more space under my deck to mount these batteries

These days i'm still thinking how to put a sprocket on my rear wheel and how to build my rear fork with space to mount the motor...I want to have everything sorted out before I start buying stuff.

Greets, Tuur

No further process for the moment... the motor 6364 is not in stock...
No motor no pleasure...

So, I'm waiting for it to come back in stock...

Hi,

I bought an electric stand up scooter with a 6374 170 Kv motor, it can give you ideas :
http://endless-sphere.com/forums/viewtopic.php?f=35&t=29136&p=420676&hilit=oxelo#p420208

I think the 6374 motor will never be in stock to Hobbycity, I think they are replaced by the SK3, like this which would fit to your scooter : http://www.hobbyking.com/hobbycity/store/__18181__Turnigy_Aerodrive_SK3_6364_190kv_Brushless_Outrunner_Motor.html
Otherwise the 6374 motor are available to leadershobby : http://www.leaderhobby.com/product.asp?ID=9394001224351
http://www.leaderhobby.com/product.asp?ID=9394001224160
http://www.leaderhobby.com/product.asp?ID=9394001224730
I ordered the 6354 200 kv motor for my folding bike to Leadershobby, and I'm very happy with this shop.
Don't hesitate if you have any other question.

Eric

Heads up, DO NOT buy the hobbyking LIPO4 thinking that it will deliver the "20C" or "10C" or "30C", whatever it lists. From everything I've read, HK LiPO4 is the same quality LIPO4 that Ping batteries are made from. (I.E, 1-2C)

If you really want to use a 'safer' chemistry, and you want to keep the pack small in total wh but with high amp draw, you'll need a123, either made from used Dewault packs or purchased from Cell_Man. Theoretically, depending on your expected load, you might be able to use LiPO4 too.


But, really, I think that you should be using LiPo. Thats really the most appropriate for this kind of super-lightweight and high-amp load. If you cant charge them attended, I mean, worse case you can just charge them outside, in a little brick fenced area. Some of the most important rules are just to never discharge below 2v [You're not supposed to be discharging below 3v but 2v is critical to avoid], and if you do, to read up online about how to recharge them (recharging them after an excessive discharge is also dangerous). You really should be ok, provided you start with good fodder (I've nervous about my battery because I know its also made of faulty HK Lipo though I hope to use it within its faulty parameters).

If you didn't care as much about the size and weight, then I would use LiPO4. Foremost my post is just to let you know- dont expect much of the HK LiPO4. The Lipo mght be rated properly, but the LIPO4 is not remotely.

thanks for your advice kin!

Last week I met a friend who has several RC planes and cars so I attacked him with questions

He told me the same as you did, and mentioned that if you use lipo batteries on a normal level and do not discharge them to deeply they are not as dangerous as I thought in the first place.



for the rest of the project I am going to order a bunch of mechanical parts at electricscooterparts.com:
55tooth sprocket

13tooth and a 16tooth front sprocket; that because I dont really know or the scooter will be going to fast or not, and this way it will be easy to adapt by just changing the front sprocket...I will be making the rear fork with slip holes so that i can use axle tension adjusters

also a thumb throttle: thought it was better and more compact then a complete handle.

and a brake lever with a switch that i intend to use to brake electrically with the Car ESC that I'll be using.

After a lot of work at the company and work for school I started again with my little project.

My electrical and mechanical parts have arrived and I started drawing in Solidworks...

My mechanical parts and other parts from electricscooterparts.com were delivered in BRASIL in stead of BELGIUM (allmost the other side of the world), a mistake of the delivery company.
Anyway, I got them with a big delay but they arrived good.

I bought 3 different sizes for my front sprocket, like this I can allways change it if I think the scooter is going to fast or to slow...

I choze a thumb throttle because it looked a bit more smooth to me.

Then I bought a chain tensioner to maybe adapt it and use it, I'll see or I'll need it...

Also I bought a brake lever with a switch because I also want to brake electrically with the ESC

Then for the mechanical part:

I took out the rear fork of the scooter to measure the positions of the holes used to mount the suspension and the brake.

I had several ideas where to mount the motor but this one seems the best for this moment:

As you can see the motor comes out from one side, I do not really like this because of strength issues, but i finally decided to do it because it looks much better with the rest of the scooter, a much wider rear fork would be a bot ridiculous...

The batteries fit quite good under the scooter.
They just stick out a bit, so I'll be making a metal cover to protect the batteries

Any advice or comments about the mechanical design are welcome. I am not finished yet if course...

I'll also start drawing a mounting frame for hall sensors, I was thinking to 3D print this, looks to me to be the easiest technology to make something small and precise...

But the adding Hall sensors is still something new for me, I do not know how to connect them with my 150Amp hobbyking car ESC (No wiring diagram) and I do not know where to put the hall sensors on the motors, but I'm sure I'll find information on Endless sphere!

I have a design for a mount for the S411A hall sensors from Honeywell:

I think of installing the mount at a distance of 3mm from the spinning motor:
like this the centerpoint of the sensors will be at around 4,5mm from the outside can of the motor...

Some remarks maybe? Is 4,5mm enough, too much? ... thanks!

looking good!!

How is your project????? Pleeeeeeeease tell us more!!!!

Hi,

I had a lot of work for school but finally graduated.

Now I am still working on the design of the rear fork. I'm still not really happy with the previous design.
The problem is that I do not have access to machinery for milling or bending etc. So the design has to be quite easy to build.

I'll post updates as soon as there are some..

Bye,

Finally picked up this project again.

Updates:
A colleague helped me with the design of the baseplate which made it easier to continue designing.


I bought a 200mm rim with air tire, think it'll be nicer on the road.


Designing 90T timing pulley: will probably be some lasercutted plates that I'll stack together.


The lipo's I impulsively bought in the beginning are more or less dead and I read about limn batteries so now I'm thinking about Sony V3 batteries.
In my deck I'll be able to stack a 5s5p which should be enough.


Still looking for an esc that beautifully fits. for the moment an alien power system 120A 2-8S Evolution 3 ESC BEC Twin-Sensored would look nice
(but I would only be using 1 of the 2 escs... )


Also trying to find a good solution for the rear fork and motor mount.
This is the best I've come up with so far: I was thinking to make this in 3mm stainless what do you think?

View attachment 1
Around the motor I was going to reinforce the rear fork with an extra round plate:

The design of the rear suspension swing/mount looks superb!

You should know you can buy a single 8s-120a Flier ESC for about 60 usd from Aliexpress (sensorless though...)

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,

Kris