Turnigy Aerodrive Scooter (she'll be quick I hope)

Keith_hill

10 mW
Joined
Oct 29, 2016
Messages
34
Helo All!

I've been reading and thinking and designing and machining recently - really looking forward to riding my scooter when finished.
I thought I'd share what I have been up to on here and garner your opinions / advice.

First of all, I'm an Engineer who really has little experience with electric systems so I decided to start a design from scratch. My day job is an Engineering Manager at a luxury car firm in Cheshire.
So, I was given a lovely Turnigy Aerodrive 149kv motor by my good friend Paul Statham (from http://www.easycomposites.co.uk - if you need carbon fibre and associated materials) and I started to scheme
around that as a starting point.

I've always wanted to have a scooter that is a bit too fast to ride and leaves you gingerly putting it back in the garage wishing that it would behave - so I hope i'm on the right track. The motor seems to be an excellent starting point given the super low 149kv rating, by my reckoning this should mean excellent torque.
My target is to be able to reach 25mph (40kph) with PLENTY of torque to get me there.

After a few beers, and writing numbers into a spreadsheet to help me understand what is going on I cam up with the following specification:

- Turnigy Aerodrive 149kv outrunner motor
- x2 6600mah Li-Po 6S (10C) batteries
- Alien EV ESC Jet 120amp 12s (http://alienpowersystem.com/shop/esc/alien-120a-3-12s-jet-esc-hv/)
- 5:1 gear reduction, chain drive (go-ped 52 tooth chain ring)
- Go-ped 6" SRT wheels (complete assemblies directly from Go-ped USA)

I decided to source some go-ped 6" SRT wheels directly from Go-ped USA, the rear wheel has the stand-offs to allow a chain ring to be mounted. I went for these largely because I like the look of them and 6" is about the diameter I am happy with, any bigger and you get the 'offroad' look and any smaller its all a bit skate park for me.

Anyway, I started to design using my increasingly favourite software: Autodesk Fusion 360, if you haven't yet checked this out, get on it NOW. it rivals CATIA for general design (possibly not large assemblies) and has full CAM capability.
I'm machining all of the components myself as I recently bought a Sieg KX3 CNC machine from Arc Eurotrade in Leicester (great guys in there). This project is allowing me to work on my manual skills that would have been fulfilled if I had served an apprenticeship. I would recommend getting a milling machine to anyone by the way.

I'll keep you all posted with more coherent posts but for now, please have a look at a few photos of my progress:

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Those mounts look scrumptious, I'd say your in the right ball park motor and battery wise for the speed your aiming to achieve, This will be very upmarket by the sounds of it good luck look forward to your posts.
 
wow :p love it ! the wheel arm / motor mount got a crazy look !!
file.php
if you want more, why not try to combine some battery you get to go to 9/10S :twisted: ?!

Good DIY, I stay here :mrgreen:
 
Nice job!
 
while the work you have done looks amazing... I think you are going to be disappointed in the scooter.
It will not be so quick that its scary.. it will actually be slower than a goped with the torkinator aftermarket motor.

It will move, but it will accelerate like an electric skateboard. Fun, but not scary fast. if thats your goal than its an excellent job... but if you want it to be scary quick like you claimed... you're going to need more power... like a 80mm motor, and an ebike controller.
 
Hello All,

Thanks for your comments, I think I'll be asking questions soon to get me a bit further along!

So the speed thing, I was aiming for 25mph which isn't almighty fast but probably quick enough on a small scooter, I am hoping to have pretty swift acceleration however - we'll see.
I will be using 2x 6S cells in series to give me 12S power, it certainly seems to have some 'go' on the bench: https://youtu.be/v0X5_WOyAMs

I have added below a few more images but this time from Fusion 360 to show you what I'm aiming for:

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Actually I do have a question: what would you recommend for battery monitoring? I.e. currently I have no way of telling what charge level the cells are at other than the charger or a multimeter.
I don't want to drain the batteries and suffer a one-way trip for them.

Looking forward to hearing from you!

Keith

(BTW Ian Hill is my Dads name - interesting coincidence!)
 
I made this sheet to help me out sizing the electronics - perhaps it would be useful to others? Or perhaps you could correct me if I have made some mistakes??
The range predictions are to be taken with a 'pinch of salt' I reckon..

View attachment Power Calculations.xlsx

Keith
 
How do you plan on charging Keith rc charger or BMS, I'd say BMS for a nice build like this and use a cycle anaylist for the display, One thing I would say is add external halls to the motor and run it with a sensored controller can use regen then.
Ive seen Bluetooth adjustable controllers with sinewave and regen like below the 12fet be perfect for this.
https://endless-sphere.com/forums/viewtopic.php?f=31&t=75888&hilit=12fet+Bluetooth+controller
 
Hi, I'll be charging rather clumsily at first; once 6S brick at a time on an RC charger.
The plan for this project is to keep it compact, i'd love to use a proper mosfet controller like on an e-Bike but I reckon it'd become quite bulky.
If you look at the CAD images i posted, you'll see that I have shot myself in the foot a bit, a central structure is nice but limiting for electronics - especially when I'm aiming to keep the thing narrow.
I'll be welding all of the frame together this week then working on a surround to keep the electrics safe.

On the cycle analyst point, can they be used with the set-up I am proposing to begin with?

Keith
 
I think you would need to use a shunt and monitor similar to what ive used on my faggio
 
Thanks Ian, I'll study your build - from what I just saw it looks really bloomin' powerful! very cool.
Yes I think the next step is a proper e-bike controller etc...
 
Heres a build with the same motor: https://endless-sphere.com/forums/viewtopic.php?f=35&t=62155
and heres my build with a larger motor: https://endless-sphere.com/forums/viewtopic.php?f=35&t=67812
and heres another build: https://endless-sphere.com/forums/viewtopic.php?f=35&t=72381
 
Thanks Mr Dude!

It looks like I have inadvertently designed a go-ped style frame but out of Aluminium.
Your builds look great, I look forward to getting more stuck into the electrics side of it all - I fancy creating some nice battery cells to better fit my space.
 
The market is moving to 21700 cells so 18650 prices should drop a fair bit soon.
I like the idea of turnigy 16ah graphene lipos, 2×6s packs in an 12s1p config in your case, laying them in a milled bit of aluminium baseplate with a waterproofing lid/footplate for compressing of the cells and heatsinking them at the same time in the massive bit of alloy,
With the milling skills you have you could mount the controller all the electronics in there and put ribs on it like an engine block so its super rigid and fins on the outside so it runs cool be a damn expensive bit of metal mind and some hours to mill and design it.
 
True one solid block would be bucks if damaged on the mill or when riding i be like :oops: :evil: all at once.
Maybe heat sinks could be tig welded to the bottom of an ally box section with Inner ribbed supports so the air flow u der the scooter cools the inner electronics and the rear can mounted on a swing arm type affair but with an inboard shock and linkage to keep it all compact but very effective.
 
I like the idea of machining a nice section to house the batteries etc with a heat sink outer design.
Unfortunately, my machine is pretty small and I probably couldn't make a part much bigger that the rear bracket section i have shown.
Machining costs are relatively low, the billet aluminium for the bracket was around £12 (6082 T6) and the machine its self is a hobby Sieg KX3 - I paid ~£5k which sounds a lot but it is something that I have always wanted to buy and I make loads of stuff on it.

How important is the compression of the cells? should I add something to provide constraint on all sides for my first build?
 
Its not necessary but if you are going with lipo it will be a safety thing to help keep puffing cells at bay with better heat dissipation and more even compression, its only applied on the faces with a few Newton's, cut the cells out of their shrink wrap that tends to place pressure on the edges of the cells and adds no cooling property's it insulates them if anything, keep the manufactures stacking method just add a rigid plate either side instead of the shrink.
 
On the contrary you should allow some margin for lipo swelling... Do not constraint them by something tight and rigid.
 
north said:
On the contrary you should allow some margin for lipo swelling... Do not constraint them by something tight and rigid.

That is not accurate.
pouch lipo requires mild compression...

cylindrical cell may benefit from not being overly constrained, but it isnt a huge issue either way.

for an idea of the compression needed... heatshrink works for the RC guys... but the OEM EV packs will shorten by inches in compression... (to be fair, they're huge and they often have "springy" internal pieces to hold tension on each cell.

heatshrink or even carefully applied tape can suffice, so you dont need to make a billet battery holder.


If your battery is producing so much heat that it needs a billet heatsink, you have other issues... like an undersized battery, or a failing cell.
 
Yes, mild compression, but it should be by a flexible structure not rigid, right? Please correct me if I'm wrong.

Nice build btw, very interesting to follow!
 
north said:
Yes, mild compression, but it should be by a flexible structure not rigid, right? Please correct me if I'm wrong.

Nice build btw, very interesting to follow!
doesnt really matter. OEMs use everything from rigid flat ends bolted for pressure to special cases with spring flats. Consumer electronics often use the circuit board and case, both are rigid. Hobby packs use heatshrink or hard cases.
The thing to remember is that if left unconstrained, the pack will have a higher internal resistance... and even if that doesnt matter, it may swell over time to fit its area.
 
I think I'll leave my cells alone for the time being.
I'm hoping to get all of the welding sorted this week then I'll have something to ride around on - can't wait to share it!
 
I've been welding and assembling over the past few days. So excited this morning to have a play, I quickly discovered that it has a tendency to wheelie even just on 6S (not tried 12S yet) Either i'm a bit of a pussy or just need to get used to riding it.
The geometry is a bit strange, the handle bars need to be further forward I reckon, easily rectified though...

I'll play with the Alien ESC throttle settings tomorrow: it is looking like the exponential curve setting is more manageable.
I'll post some videos soon of my initial test flights.

Photos:
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Very nice, I like the fact the handlebars are height adjustable and the front forks rake forward with a single arm it looks a very nice bit if kit the frame is stunning looks super light.
 
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