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Topic: E-Chopper (ex. Expectations & Torque) (Read 3 times) previous topic - next topic

Runaway Pancake

Feb 19, 2012, 08:22 pm Last Edit: May 07, 2012, 02:04 am by Runaway Pancake Reason: 1
I have what seems to be a pretty strong motor, permanent magnet.  The NPC-2212.  Maybe they make for wheel chairs or winches?
I wonder if it could be used to make a modest electric bicycle.
There are a lots of "what ifs": fit the existing pedal gear (or other) on this motor... welding a mounting bracket for the motor to the bike frame... -- I get that.

I wouldn't want to invest a lot of time and effort only to find that it's under-powered.
Can anyone venture a learned opinion?  
Do this motor have the goods (Y/N) ?

Some figures --
0.22 in/lb    6.2A   285rpm   0.001hp
28.1 in/lb   10.2A  252rpm   0.11hp
49.6 in/lb   23.6A  227rpm   0.18hp
69.1 in/lb   31.3A  199rpm   0.2hp
91.4 in/lb   41.4A  163rpm   0.24hp


"Hello, I must be going..."
"You gotta fight -- for your right -- to party!"
Don't react - Read.
"Who is like unto the beast? who is able to make war with him?"

MarkT

The idle current is pretty huge at 6A - indicates a lot of static friction.

0.24hp is a rather under-powered level though - 250W to 500W output would be better (1/3 to 2/3hp)

What's all this "in/lb" figures?  Is that meant to be torque?  Its nonsense units.

Ah, found webpage for it now - its very inefficient (gears don't help), may overheat in constant use, seems to be about 50% efficient or so - look for a chinese brushless hub motor, 90% efficiencies are more the order of the day.
[ I won't respond to messages, use the forum please ]

kf2qd




What's all this "in/lb" figures?  Is that meant to be torque?  Its nonsense units.




Not sure what you are used to working with, but In/Lb is an ordinary way to to write it, though the perfectionists might want to see In-Lb or even Lb-In 

MarkT

in/lb is distance divided by weight.  Torque is distance _times_ force.  in.lb  would do, but Nm is much much prefered.  I've seen this confusion over torque before, but always as N/m never m/N or equiv...
[ I won't respond to messages, use the forum please ]

Runaway Pancake

The "Dynamometer Test Results" column was labelled "torque in in/lbs"
http://www.robotmarketplace.com/products/NPC-2212.html

I checked around since, some bicycle site had figures for a casual bicyclist ranging 150-200W. 
Like that's a benchmark?  How much hp (watts) to take off from a dead stop (no "pushing off")?

I'm < 170 lbs and the bike is, guessing, 40 lbs.
Going at a fair rate (what I'd be pleased to accomplish motorised) down the street here, I was pedaling about 80rpm.
I'm not trying to devise a daily-driver or anything, just a "little" experiment, a lark.

Thanks, MarkT, for your insight.
"Hello, I must be going..."
"You gotta fight -- for your right -- to party!"
Don't react - Read.
"Who is like unto the beast? who is able to make war with him?"

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