liveforphysics
100 TW
A beautiful conversion!
Motorcycle class Hub Motor
- Thread starter markcycle
- Start date
etard
100 kW
Congrats Mark!! That should do wonders for your business. 
I think this is the perfect conversion for your motor. The performance level of te ol Brit twin bikes is right on par with current electric technology. And this Hammerhead is a beautiful example of how clean and classy a conversion can be.
I think this is the perfect conversion for your motor. The performance level of te ol Brit twin bikes is right on par with current electric technology. And this Hammerhead is a beautiful example of how clean and classy a conversion can be.
markcycle
10 kW
etard said:Congrats Mark!! That should do wonders for your business.
I think this is the perfect conversion for your motor. The performance level of te ol Brit twin bikes is right on par with current electric technology. And this Hammerhead is a beautiful example of how clean and classy a conversion can be.
Thanks all
Mark
voicecoils
1 MW
Wow, that photo should go straight to the front of your website Mark!
The hubmotor actually looks like a drum brake on a classic racing bike.
johnhead@frontiernet.net
100 mW
- Joined
- Feb 1, 2009
- Messages
- 41
Hello Mark, As if life isn't confusing enough for you. You have James Hammarhead creating beautiful looking "British/electric" motorcycles using your hub motor, and John Head, who restores British motorcycles for a hobby, making a leaning three wheeled trike using your great product. I'm eagerly looking forward to meeting you at Mid-Ohio.
Regards
John Head
Regards
John Head
Shouldn't controller output voltage be proportional to motor RPMs?
The first time (which was very recent) that I saw an electric motor (Agni) list its volts per RPM, I wondered why everything seemed to be using constant voltage.
And the graphs I've seen here back up that curiosity. For a given voltage there is a maximally efficient RPM, near the maximum RPM. It should follow that for every RPM, there is a maximally efficient voltage. And not just maximum acceleration, but maximum acceleration and efficiency of power usage.
Do the Kelly BLDC controllers output a fixed voltage, or is the output voltage the same as the input voltage? I'm hoping the latter. And if so, can I just create a manual switch to switch a battery pack's serial / parallel arrangement? Please?
This seems extremely similar to shifting mechanical gears, without the friction loss. I can see it being implemented with an interface very much like a ratcheting sequential motorcycle gear box. Without the clutch.
Hmm, I guess for increased acceleration you would want more amps and less volts, also like mechanical gears? I need to look at those graphs again. No, I think you would still want the maximally efficient voltage per RPM for maximum acceleration?
Four battery packs, 36v and 200a max (36 Headway 10a cells) each, gear equivalents:
First gear: Full parallel = 36v 800a
Second gear: Parallel / serial = 72v 400a
Third gear: Full serial = 144v 200a
I think I finally grasp the difference between amps and volts. I'm sure I've read it before: Volts = speed, amps = torque. Fast (high voltage) motor with no torque (low amps) = going nowhere. Slow (low voltage) motor with lots of torque (high amps) = definitely going somewhere, but slow (and inefficient if you don't need all the torque).
I also think an emergency mechanical disconnect switch within easy reach is a good idea. Physically separate the batteries from the controller. "When all else welds shut." Frankenstein style (knife switch).
The first time (which was very recent) that I saw an electric motor (Agni) list its volts per RPM, I wondered why everything seemed to be using constant voltage.
And the graphs I've seen here back up that curiosity. For a given voltage there is a maximally efficient RPM, near the maximum RPM. It should follow that for every RPM, there is a maximally efficient voltage. And not just maximum acceleration, but maximum acceleration and efficiency of power usage.
Do the Kelly BLDC controllers output a fixed voltage, or is the output voltage the same as the input voltage? I'm hoping the latter. And if so, can I just create a manual switch to switch a battery pack's serial / parallel arrangement? Please?
This seems extremely similar to shifting mechanical gears, without the friction loss. I can see it being implemented with an interface very much like a ratcheting sequential motorcycle gear box. Without the clutch.
Hmm, I guess for increased acceleration you would want more amps and less volts, also like mechanical gears? I need to look at those graphs again. No, I think you would still want the maximally efficient voltage per RPM for maximum acceleration?
Four battery packs, 36v and 200a max (36 Headway 10a cells) each, gear equivalents:
First gear: Full parallel = 36v 800a
Second gear: Parallel / serial = 72v 400a
Third gear: Full serial = 144v 200a
I think I finally grasp the difference between amps and volts. I'm sure I've read it before: Volts = speed, amps = torque. Fast (high voltage) motor with no torque (low amps) = going nowhere. Slow (low voltage) motor with lots of torque (high amps) = definitely going somewhere, but slow (and inefficient if you don't need all the torque).
I also think an emergency mechanical disconnect switch within easy reach is a good idea. Physically separate the batteries from the controller. "When all else welds shut." Frankenstein style (knife switch).
liveforphysics
100 TW
The motor doesnt feel voltage, only current. The PWM signal makes it possible to take a 200v pack, and switch the PWM at a 10% duty cycle so the motor acts as if its getting only 20v, then smoothly ramp up or down as needed to control the desired speed.
In your example, you've got the times to switch from series to parallel backwards. Start in series so each motor gets the full current of the controller, then switch to parallel after the RPM of the motor increases enough to have a level of BEMF that prevents it from reaching 50% of its current limit. At this speed, you swap to parallel, feel roughly no change in acceleration rate, but you're now able to maintain this rate of acceleration for about twice a high of speed, as the BEMF is halved when swapped to parallel.
But, none of this really applies to brushless motors, the most a battery series/parallel arrangement could do is save a bit of controller heating when starting out from a stop. Wouldnt change the performance much though, unless you were useing some very low C rate cells or something.
In your example, you've got the times to switch from series to parallel backwards. Start in series so each motor gets the full current of the controller, then switch to parallel after the RPM of the motor increases enough to have a level of BEMF that prevents it from reaching 50% of its current limit. At this speed, you swap to parallel, feel roughly no change in acceleration rate, but you're now able to maintain this rate of acceleration for about twice a high of speed, as the BEMF is halved when swapped to parallel.
But, none of this really applies to brushless motors, the most a battery series/parallel arrangement could do is save a bit of controller heating when starting out from a stop. Wouldnt change the performance much though, unless you were useing some very low C rate cells or something.
markcycle
10 kW
Wheelies
603 motor in a yz125 frame
100 15AH volts of Lipo
[youtube]oYIkQkJKHTw[/youtube]
603 motor in a yz125 frame
100 15AH volts of Lipo
[youtube]oYIkQkJKHTw[/youtube]
Jay64
100 kW
Nice! 8) Have you tried what we were talking about in Ohio? You know, engage the brake cut off while ramping up the throttle? And then "pop" the brake cut off?
We_Go_E_Go
1 µW
- Joined
- Jul 15, 2010
- Messages
- 1
COOL
markcycle
10 kW
DasDouble
100 kW
subscribed
JRP3
1 kW
To an inactive 6 year old thread?DasDouble said:
DasDouble
100 kW
This of for me so I can find it better later.
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