Merging the R/C crowd with EVers

[slayer]

Looks like astroflight is going in the e bike biz...
see this link 12 to 48 volts 50 amps controller with throttle works with most bike motor
http://www.astroflight.com/index.php?main_page=index&cPath=20&zenid=1cf987c4tqrmk3mh2j22hqmlhuvq930q

 

[Miles]

Yes, I noticed that. I assumed they were for brushed motors. Would be neat if they could integrate their servo controller into a throttle....

 

[rkosiorek]

looking at the connectors i only see 2 wires going out for a motor. so this would be for brushed motors only?

rick

 

[Miles]

looking at the connectors i only see 2 wires going out for a motor. so this would be for brushed motors only?
rick

I'm sure that's true, but I've emailed Bob Boucher about them - will report back...

 

[Miles]

List of brushless motors used in RC applications (outrunners & inrunners):
http://www.progressiverc.com/Brushless_Motor.html

 

[Knuckles]

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[The7]

Gosh! I guess I need a 1-GHz MCU! Ha Ha We So Crazy!

Not necessary!
They are most likely 1 or 2 pole-pairs motors.
If the speed is 12000 rpm, the motor frequency is only 200 Hz for 1 pole-pair or 400 Hz for 2 pole-pairs. less demanding than Puma.

 

[Knuckles]

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[The7]

Battery Voltage = 48V
Kv = 130 rpm/v
Speed = 130 x 48 = 6240 rpm
Even if it has 4 pole-pairs, the motor frequency is only 416 Hz. No big deal!

 

[Knuckles]

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[paultrafalgar]

...
But there are still some technicle hurdles. 300 hours on a RC motor is a full life. Thats a bout what the bearings can handle before expiring. The RPMs are also high. a bike wheel needs to cruse at 200 to 300 rpm. Most RC motors run 10-40 thousand RPM. Gear reduction on that scale kills efficancy, but also causes some other problems.

I've got a 400 watt Eflite sitting in a wrecked airframe thats taunts me daily. the total weight of the motorand controller was under 4 ounces. For under 10 pounds of equipment and batteries, I could build it into a 40 mile range bike with plenty of power, Comparable to my 500 watt C-lyte Hubmotor.... if there was a way to deal with its 35,000 RPM at 11 volts.

Which is exactly why I started this thread:
http://endless-sphere.com/forums/viewtopic.php?f=7&t=4753&start=0&st=0&sk=t&sd=a
You overcome the gear reduction problem completely. No expensive machining, no bearing stress, no multi-stage reduction - belts chains etc. I just have to convince you guys that a very small generator (not Honda GX35 size) - think electric toothbrush induction charger + DC-DC converter to charge smaller LiFePO4 is the way to go!
But what would a layman like me know

 

[Miles]

Not sure I follow, Paul.

I can see the advantages of having an onboard generator, sure.. Are you just proposing a hub motor, to go with it?


Why does everything gets so exaggerated... RC motors either induce some kind of Paulian conversion (safe) or are deemed to be completely impractical. Get a grip, folks

 

[paultrafalgar]

Yes, you'd have to use another motor for that way of working, whether hub or geared. Your right, too much excitement not enough reflection, perhaps

 

[Miles]

Well, you could just couple the Honda GX35 to a Nu Vinci CVT and forget all this pesky electrical stuff

 

[paultrafalgar]

What! And be banished by all these good folks here for sacrilege?! Never!
Let the juice be with us! Not the gas!

 

[docnjoj]

Recumpence certainly proved it could be done successfully.
otherDoc

 

[Miles]

Well, at least he's made a start....

 

[Knuckles]

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[The7]

Can I still have propellers?

How many do you want?

 

[docnjoj]

Would be great fans if set up as pullers in the front of the bike! Keep U kool!!!!
otherDoc

 

[recumpence]

Yes it can be done and yes it works fine.

My Wh per mile is 15.69 (real world riding) at 20 mph and a touch over 17 WH per mile at 35 mph. I would say that is efficient. I also pull my kids in a Burley trailer at 12 to 14 MPH and still average 16.7 WH per mile without any significant heat build up. So, obviously, these mtoros do not have to mantain a narrow RPM range to be run efficiently.

Also, I have over 500 hours run time on one AXI outrunner. It started in a custom twin rotor heli, then moved to a hand made RC truck. From there, I mounted it in my CNC (can be seen on my build thread). These motors last a LOOOONG time considering their RPM and power output.

I agree, though, these motors are not easy to mount and drive a bike with. But, the myths about short lives for the components, heat build up, poor efficiency, is all nonesense assuming the system is setup well and components are paired properly.

Lastly, my reduction system is not large by any means. It fits in the palm of my hand. I have (at this point) less than 17 pounds of equipment on my bike total including 480 WH pack and it all fits under the seat.

I think part of the problem is that this is so different. Many people seem reluctant to believe it will work. That is the reason I took a video of it running.

Is this the best e-bike in the world? I doubt it. Is it a step in the right direction? That's what I am hoping.

Anyway, great thread. Lots of good discussion happening here!

Matt

 

[Knuckles]

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[TylerDurden]

I was thinking two turbo jets ... ' One on each side of the e bike … like “nacelles” ...

You could call it "The Scotch Bonnet".

 

[Knuckles]

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[Microbatman]

Most of the problem of a sensorless controller is to start the motor moving with enough power to keep it going. Picking a couple of coils to energize, hope that the rotor will orient to that position and then start a commutation sequence. the first few pulses of that commutation sequence are delivered automatically in a predetermined sequence to get the rotor moving fast enough to generate some BEMF. until the motor does start to produce BEMF the commutation is more or less hit and miss. ower.

Rkosiorek

Well said very easy to understand.

Anyone know how fast is fast enough to to generate some BEMF?

Would a geared motor such as BMC or EZee be fast enough?