E-bike project (RC mid drive system)

brunotollot

100 W
Joined
Jun 14, 2012
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118
Location
UK
Hi.

Like Miles suggestion i have opened a new topic. I would like to share my idea and take some suggestion from who have lot of experience.

I have already started to build the E-bike. Then i would like to do a mid drive system with RC motor and, of course, RC controller (ALIEN). I was thinking to do something like plug & play (all the mechanical and electronics) so it could be a future electric conversion kit.

I'm not sure about the motor. Outrunner or inrunner. Actually i think that one of the big difference is that, for how they are build, the outrunner should have more torque, but everything depends to the quality of the motor itself. A good inrunner can be better of a bad outrunner or viceversa. I have a supplier that can do custom inrunner so i was think about a 8000watt, between 100 and 150KV with hall sensor and temperature sensor that anyway maybe is better for the small size.

Any suggestion?

Battery: I was thinking to use 15S ( 3 x 5S) Lipo battery pack. Not sure between 8000mah zippy or 8000mah Turnigy nanotech.

Any suggestion??

BMS system. I find a company: They said that they can do some discount if i will buy more then one, so if anyone know about BMS and think that this is a good system, please let me know, so i can make an offer.

Here the website:

http://www.foundingpower.com/a/home/

What do you think?

Sorry if i don't let you understand completely for my bad english...

Here the Bike:
 

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I am very interested to see what your controller can do, and this custom inrunner motor as well. For your own use, if you're using LiPo and you're pretty good with electronics and batteries, you might consider using a balance charger and some cell voltage monitors or a throttle low voltage cutoff board instead of a BMS.
 
Hi and thanks for the info. The point is that i would like a BMS for a fast and correct charge. If i use a balance charge i have to charge one pack a time or use a parallel charging port that anyway i think is not precise like a BMS that check every single cell. Right?

Regards
 
Hi Bruno,

I've moved your thread to Non-hub motor drives. I think it will get a better response there.

A motor with a speed constant of 125 rpm/V, on 15s, will run at about 6000rpm under load. In order to get 8000 watts from it at that speed requires a torque of over 12 Nm......

You might like to refer to this thread: http://www.endless-sphere.com/forums/viewtopic.php?f=30&t=45489
 
Battery's, Controller's, motor's ,...are the "electrical" part of the system and there are some "off the shelf" commercial solutions for those components.
BUT, the key to a successful "mid drive" is the mechanical part of the drive.
Reduction gearing, jack shaft or gear box ?
Freewheel systems, ?
Through the existing chain drive , or separate drive to the wheel ?
you need to carefully consider these areas before finalizing your Motor choice and voltage range.
 
Hi and thanks. Yes. The mechanicaI part is very important. I was think to use the existing chain and add a reduction belt system. With freewheel. 1:5 motor pulley to belt cog. Then freewheel 1:5 to existing chain. 7 speed on the rear hub.
 
Hi Bruno,

You're bike looks very nice. What controller do you plan to use? There aren't much RC controllers made for sensored motors. The Castle Creations ICE HV 160 is a very popular ESC for on E-Bikes, however it only goes up to 12S LiPo and doesn't support sensored motors. You might want to take a look at MGM controllers, capable of 15S LiPo and sensored motors: http://mgm-compro.com/index.php?tid=brushless-speed-controllers-tmm-25063-3-x-series-32-bit-system. Downside is they are very expensive and there is no one on this forum that ever used one in an E-Bike.
You could also look to non-RC controllers like Kelly, there are some members on the forum who used them before.

A non-hub E-bike needs a lot of patience so take your time. Good luck with your build!
 
brunotollot said:
I was think to use the existing chain and add a reduction belt system. With freewheel. 1:5 motor pulley to belt cog. Then freewheel 1:5 to existing chain. 7 speed on the rear hub.

...A motor with a speed constant of 125 rpm/V, on 15s, will run at about 6000rpm under load.

If you intend to be able to pedal as well as use the motor, you will need more reduction..or a lower speed motor.
 
Thanks. The controller will be the Alien, of course. I will test it in sensored mode as soon as i will finish the bike. Then i will understand what i need to improve, if the Bike will work. Here i can take lots of suggestion.

Also, yes, i would like to pedal aswell. Thanks for the info


Regards
 
All the parts are finally arrived. Work in progress... I need a 48 Hours day.... :) Thanks Mr Richard..... CNC Engineer

Sample.JPG

Gearbox test 1.JPG

Gearbox test 2.JPG

 
hey bruno,

nice project :D very dangerous design. You can not put 8000Watts through a bicycle drive train. Go single speed instead!

You say your inrunner is custom made? Then i'd go for a 24p/20p motor and wind it for about 75KV. Makes reduction simple. Ther's no need for a shifter gearbox at all at this power level. Remember, this is still a bicycle frame, you wont drive faster than 80km/h. If you'd want to you'd need a different frame geometry ;)

My suggestion would be:
24t/20p motor, 75KV
15s zippy battery, 170amps battery current limit
76/15t single speed reduction, 3/8 x 7/32 chain
max speed: 80km/h, max hill gain: 77.7% @ 150kg vehicle weight :shock: really no need for shifting ;)

made a little calc:

Edit: The 76T sprocket on the rear wheel would be larger than the 203mm rear brake disk, not good looking. Go for a 65/13t chain drive, then sprocket and brake disk have equal size, just for the look ;)
 

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THANKS. The motor choice in the end is 12095 80KV 15So 8000mAh so:


4700rpm- 72/18

=1175rpm

1175rpm- 12/44

=320rpm

=320 – 44/14

=1005rpm X (126 m/m)

=126kph
 
Hey crossbreak!
crossbreak said:
You can not put 8000Watts through a bicycle drive train.
Any idea on the max power and/or torque you can put through a bicycle drive train?
Posts, XLS's, links to read..?
Thanks.

crossbreak said:
Remember, this is still a bicycle frame, you wont drive faster than 80km/h. If you'd want to you'd need a different frame geometry ;)
I imagine that a Scott Gambler, beefy frame and headset angle would make it ideal for a lot more speed.
 
Any idea on the max power and/or torque you can put through a bicycle drive train?

the max average power you push through a dereilleur is 1200Watts - At least all commercial middrives using derailleurs, are cut by software at 1200Watts and use 12T for the fastest gear.

If you use more than 12T as the smallest sprocket, you can push more than 1200Watts through a derailleur drive. This should be added to the wiki.
 
I regularly see 2500 to 2800w on my current bike and I used to see 3800w with peak of close to 5000w with my last motor. My bike runs the motor through the dérailleur and 3 gears with bicycle chain. I have never had a problem with the dérailleur or the bicycle chain. When cruising at WOT 48kph, I usually see between 1000w and 2000w. I always let up on the throttle to shift and often pedal once or twice to change gears. If I do use the motor, I roll on slowly and smoothly. I don't crack the throttle ever, as it would jump the bike out from under me.

Clay
 
hi dont know if theres any ideas to be had from this but im running 2 1200w cyclones through a nuvinci 360 unfortunatle i have no idea of max power through this but it hasnt failed yet
 
guess the stated 1200Watts are average, not peak. I'll write some mails and let loose on my german charm :D post the answer here.


flyinmonkie said:
I regularly see 2500 to 2800w on my current bike and I used to see 3800w with peak of close to 5000w with my last motor. My bike runs the motor through the dérailleur and 3 gears with bicycle chain. I have never had a problem [...]

Clay

Interesting, which cassette do you use and how many miles does it last?
 
Yes with good components I have seen others run in excess of 5000 watts as well. I think his name was motomoto or something like that who had a 60MPH bike through the derailleur and STD chain. I don't recall him breaking one either...


EDIT: Here is his thread:

http://endless-sphere.com/forums/viewtopic.php?f=28&t=25193



Awesome bike build. Too bad he stopped??
 
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