Saturday, June 17, 2017

Big Bulk Box Bike

https://www.facebook.com/AnywhereBerlin/?pnref=story
If anyone can build these street legal they can sell a lot more of them”

This is the most heavy duty “looking” cargo bike that I have seen made in the industrialized world. Unfortunately they used two hub motors. Making this street illegal in Washington state, and a number of other places.
People are so obsessed with speed they think that even a large heavy duty cycle truck should be able to drive as fast a motorcycle. Yet they refuse to consider that there are good reasons that motorcycles have really powerful brakes and very heavy duty tires.
Not only are hub motors a waste of energy, but they use more energy than is needed to climb steep hills.
I am going to have to stop writing this blog, people just don't care. But if you want to sell these vehicles use your brain by reading these pages.

Electric Overdrive / Magnetic Gear Motors? / Fixed Gear Drives (Non-Hub Direct Rear Drives) / New Motor Technologies / Custom Belt Drive / Two speed gear boxes for bicycles







Two motors with two controllers will give you more speed with a larger use of power. But an extreme gear reduction would use less power, and just not because of the lack of speed.





Here's the simulation for dual MAC8T motors assuming equal sized wheels with identical controllers. As you can see the motors are out of the controller-limited region (after the peak inflection point of the red motor curve) and so are not bound by the controller amp rating and are running at near peak efficiency even though they are climbing a 9.5% grade. This requires about 54 battery amps which should not be difficult to achieve (you want to run a single battery - avoid the control and monitoring complications of using two).


https://endless-sphere.com/forums
/viewtopic.php?f=3&t=89705

Here's the simulation for dual MAC8T motors assuming equal sized wheels with identical controllers. As you can see the motors are out of the controller-limited region (after the peak inflection point of the red motor curve) and so are not bound by the controller amp rating and are running at near peak efficiency even though they are climbing a 9.5% grade.
This requires about 54 battery amps which should not be difficult to achieve (you want to run a single battery - avoid the control and monitoring complications of using two).

This technique is essentially a graphical analysis that gives viable results given the constraint of equal sized wheels and identical motors and controllers:

  1. Set up for one motor/controller/wheel and run the simulation
  2. Scrub the cursor back and forth, until the required load power is twice the delivered motor power (for 2 motors)


In the above example, you need 1600W to climb the grade and each motor will be loafing and supplying only 800W.


two motors are better than one



If you run equal wheels/motors/controllers, you can use simple Infineon trap controllers and will get optimum efficiency under almost all circumstances using a single throttle with no special tuning.

Recommend, would be a CA3 to drive the two controllers to get the throttle ramping, and current throttle for smooth operation + 2WD PAS and/or auto-cruise if you wish... Since the drives are the same, you can use the CA to monitor the temperature of either motor and assume the other motor is about the same temperature. This gets you automatic thermal power rollback to avoid cooking the motors if you try to overtax them.
    Remember, electric motor power specifications are in terms of 'rated power' not the actual power you run it at. So a 500W MAC can easily be run at 1500W although it will heat up and eventually overheat with this overrated operation. But legally, it's still only a '500W' motor.

Do not be confused by comments about testing the output of a bike - the traffic statutes are written to facilitate field enforcement - so many cc's or so many rated Watts - not the actual hp output of a motor which an officer could not possibly measure. He needs to be able to make a decision based only a quick look at a motorcycle model plate or wattage sticker - hence the way the statutes are defined (of course there are some really confused state statutes out there, but that's another matter...) But a label that says 500w would help.




dual controler assembly


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