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This
is the most heavy duty “looking” cargo bike that I have seen made
in the industrialized world. Unfortunately they used two hub motors.
Obviously the laws must change to accommodate more hill climbing
power with controlled speed output, and low enough gears to keep the
top speed down to 20mph. That means you need a second motor. A mid
mounted motor with a single speed gear reduction is best with a
hubmotor.
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.
Motorcycles
need to be able to drive at 45mph. It would be cheaper to drive at a
low speed of 20mph. Especially if you must use a single speed
hubmotor. Two motors work well if one is geared low gear ratio] and
the other a direct drive [much higher gear ratio] where as the stress
go from the high gear to the low gear as the vehicle slows down by
way of too much gravity.
However
I believe that most cops are not looking for large motors, only
“fuelish” speeders. There is nothing wrong with hauling 600 to
700lbs at 20mph if you have good brakes with electric cut off levers.
For
a “Mid Mounted” single
speed drive
I would use the cyclone 4kw [or one even larger if possible]. It is
wider and has the potential of producing 130Nm max torque thrust. And
still has the same RPMs with the same Planetary gear reduction as the
shorter motor used for the mid-drive. Max amps being a little higher
45a. Actually climbing steep hills with even 450lbs total combined
weight needs so much power that you really need an ultra low gear,
that would be so slow that you might fall over. So that two motors
really are the way to go, even if one is a hub motor. Running both at
the same time to keep them from overheating.
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:
- Set up for one motor/controller/wheel and run the simulation
- 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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