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Old 06-05-2017, 06:20 PM   #10 (permalink)
Cyborg ECU
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Join Date: Mar 2011
Location: Coastal Southern California
Posts: 6,297

Black and Green - '98 Honda Civic DX Coupe
Team Honda
90 day: 66.42 mpg (US)

Black and Red - '00 Nashbar Custom built eBike
90 day: 3671.43 mpg (US)
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Originally Posted by puddleglum View Post
I would interpret the "1000 rpm max" to be the free run speed of the motor at 72 volts (rated voltage), not the max rpm that the motor can be spun up to without power. It's max safe rpm is probably a lot higher. It says it can be run at 144 volts which would double the rpm right there. there is still the issue of the anemic torque output though which would limit its use in a car unless you were going to fit 4 of them...
This discussion got me reading further online (Endless-sphere site and such places). It seems a 30% buffer above max load is a common saftey design feature. But that means with tall tires on 15" wheels this hub motor would start to come apart at about 80-85mph MAX.

Originally Posted by thingstodo View Post
... There is not much clearance between the rotor and stator on a modern electric motor of any type - induction, PM, BDC. There is a lot of load on the bearings - since that is what is holding the car off the ground ... and taking the bumps since the motor is unsprung ... no suspension to smooth things out. Only one bearing on one side gives the hub motor a couple of additional challenges. After a few thousandths of an inch of wear on certain parts of the bearing ... some part of the stator meets some part of the rotor and *BAD* things happen. ...
Yeeoww! Makes sense though. Seems like it is not the kind of thing to try on a daily driver, hahaha!

Originally Posted by NeilBlanchard View Post
... The obvious answer is to use tandem motors with half shafts. Then you don't have gear losses, and you have much lower unsprung weight, too.
But that takes more space. A hub motor set up would save cargo space and it seems like an easier conversion. But the hub motors obviously need more development.
See my car's mod & maintenance thread and my electric bicycle's thread for ongoing projects. I will rebuild Black and Green over decades as parts die, until it becomes a different car of roughly the same shape and color. My minimum fuel economy goal is 55 mpg while averaging posted speed limits. I generally top 60 mpg. See also my Honda manual transmission specs thread.

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