Experts (or not) - do you think this will be successful?

le15otl

le15otl

100 W
Joined
Feb 24, 2015
Messages
147
Location
Gloucestershire, England
I'm using this motor
http://www.hobbyking.com/hobbyking/store/__22036__NTM_Prop_Drive_50_60_270KV_2400W.html

And a 200A ESC (un-sensored)

On a 13:1 gear ratio (which at 25V will give a max possible speed of 36mph.)
Sprocket + chain so no slips

Does this look like a project that will work?
Looking at the size of the motor it seems ridiculous but looking at the power of it, it seems it'll definitely work...

Any opinions very welcome!


Thanks
 
Is this for a powerboard? If you'd like, you could copy/paste this info to a new thread in the "standup E-scooter and E-skateboard" section....and then delete this. That would likely give you many more responses. If you'd prefer, I could move this thread there?

http://endless-sphere.com/forums/viewforum.php?f=35

Assuming you are talking about a powered-skateboard...you should add a couple $2 voltage ripple capacitors to the ESC inputs, and if a larger motor will fit the board you want to use, a 63mm diameter motor will have more copper mass (making it capable of taking more sustained amps without overheating). The larger diameter will also provide more torque per the same watts fed to it.

Is your planned commute flat, or are there mild hills / steep hills?
 
It's for a mountain bike, sorry I forgot to mention.
I was hoping it would be able to tackle steep (ish)hills :?

I will still order some ripple capacitors, that's a good call.

A 63mm motor will be the next to try if my one doesnt work

Thank you for the fast reply :)
 
no way geared for 36mph and unsensored.. unless you are planning to peddle up to 5-10mph before applying power
 
How about a 16:1 gear ratio? You're getting down to 30mph, about as fast as you could really want to go on a mountain bike if you have any sense, but your uphill potential improves. If you don't go with the bigger motor Mr. Magnets suggests. Just a thought.
 
13:1 is the absolute max I could manage with 25H parts.
The low weight of the motor was partly what drew me to the 50mm 270kv, I'd like to be able to use it as a normal mountain bike too.

Don't you think that giving it a quick pedal at the start will make it usable? rider/bike weight is only 70-80kg

I already have the parts so I'm going to try it anyway but maybe a 80mm motor as a mid drive is the way to go.

spinningmagnets, what controller would you recommend for something like this? Is it still possible to use RC ESC (sensored)?
http://alienpowersystem.com/shop/80mm/c80110-sensored-outrunner-brushless-motor-130kv-7000w/

Thanks a lot.
 
peddling will help and you just may get away with it, but it will only be a matter of time that you will try to pull away using throttle only and then thats it.. game over .. it happens that quick if your really serious about doing this .. then I would also have some sort of peddlec ( think thats the word ) sensor or speedo on the front wheel that will output correct signal to enable the throttle at a preset speed/peddle rotation.

edit: a better motor would be a 6473 170kv
 
Ah ok if they can burn up that fast, it's not a good solution, I'm looking for something reliable and tough to ride many miles.

Do you think the 6473 170kv will fail quite a lot less easily then?

Cheers
 
le15otl said:
Ah ok if they can burn up that fast, it's not a good solution, I'm looking for something reliable and tough to ride many miles.

Do you think the 6473 170kv will fail quite a lot less easily then?

Cheers
Click to expand...

its not the motor that will fail it will be the controller.. the 170kv motor will just allow a little more wriggle room for the reduction and also have a little more mass so it will handle the heat a little better
 
le15otl said:
I see, then could I just buy a bunch of 150A fuses and put one inline?
Click to expand...

fuses will not act fast enough to protect the controller a 150A fuse may not blow until it sees in a very short spike of 300A and by this time its to late.. the main problem is that rc ecs do not have current limiting built into them so its very easy to pop them as a motor from a stalled position can easy pull 100's of amps
 
there is not a off the shelf cheap solution to this problem .. you can either fit hall sensors to the motor and then use a infineon e-bike controller or get something that can limit the current from the rc esc i.e a CA or gear the bike slower and be very careful with the throttle and hope you don pop the rc esc.
 
I'll look into getting an infineon controller, they appear quite heavy but maybe they're just big? That would be for an 80mm motor btw, not worth investing much into mine by the sound of it.
But I'm still trying it haha :mrgreen:

Thanks again
 
gwhy! said:
there is not a off the shelf cheap solution to this problem .. you can either fit hall sensors to the motor and then use a infineon e-bike controller or get something that can limit the current from the rc esc i.e a CA or gear the bike slower and be very careful with the throttle and hope you don pop the rc esc.
Click to expand...
Does your arduino controled throttle with current sensor is reliable enough for this purpose ?
 
It limits battery and phase current so in theory it should. There is someone on this forum that is using it on a rc esc and as far as I know its working well for him
 
file.php


le15otl said:
Ah ok if they can burn up that fast, it's not a good solution, I'm looking for something reliable and tough to ride many miles.

Do you think the 6473 170kv will fail quite a lot less easily then?

Cheers
Click to expand...

What I think your dilemma is would be what befell this cosmopolitan young lad a few years back. This very bike burst into flames, there's spectacular photos here somewhere that I can't find. Racing, climbing hills, can we really say which flogs the bike more?

If I remember he had the motor, the controller AND the batteries go up. There's things you can do to minimize the risk, but danged if you don't have to go into this RC thing considering the risks. http://www.rcdude.com/Castle-Creations-Cap-Pack-p/cc-cappack.htm

A gear ratio that gets the motor to speed quickly is a safer gear ratio. When that bike is trying (And FAILING) to get up to speed, especially uphill, the heat is building. Just building. Building. . . .
 
I'll definitely keep a close eye on it's temp. I have a feeling that it not being friction drive might mean it's less susceptible to over heating as there's no friction between the motor shell and the tire. Could be wrong about that...

I'll try flashing a customisable firmware onto the ESC,
can anyone suggest the best timing setting for the motor?

Thanks
 
With a mid drive setup which you can pedal at the same time as using the motor, but also use the motor without the cranks moving, are the cranks on separate freewheels so the can move around like in this video?

https://www.youtube.com/watch?v=1MN2LXi-Qow


I'm struggling to work out how it would work having the motor driving the bike while the cranks don't move (apart from with the setup shown in the video but that seems like it would be clumsy for normal riding?)

any info or explanation is welcome

Many thanks
 
They have a free-wheeling crank that has a freewheel between the chainwheel and the bottom bracket spindle. You can see them here with the freewheel in the middle:

http://www.cyclone-tw.com/order-chainwheel.htm
 
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