[ausev] EV moto

[Chris Robison]

Note that his rear sprocket was stock. In case it's not clear from his 
description of events, this was the mistake that cost him a controller 
and has cost others their motors. You need a larger sprocket like he 
added toward the end, to allow the motor to spin faster for cooler 
running and less current draw.  Your planned maximum speed should be 
close to the motor's speed at the pack's voltage (permanent magnet 
motors are very voltage/speed linked).  This bike's maximum speed was 
actually pretty low since he was trying to keep it defined as a moped 
and yet he still blew up his Alltrax. His motor was drawing way too much 
current on a continuous basis, due to the tall gear ratio. Moving to a 
controller for a larger vehicle helped, but wasn't necessary or ideal.

Second, if you want to go faster, don't gear up, increase volts by 
adding batteries. (In the end, he ended up gearing *down*.)  To go 
faster you need more power, and just changing your gear ratio doesn't 
give you that.

Also, he's wrong about limiting current at the throttle. Adding 
resistors to the throttle will not necessarily protect the system from 
too much current draw, it will only reduce the duty cycle requested from 
the controller. At slow motor speeds, an unsophisticated controller can 
still draw too much current even with a lower effective throttle position.



  --chris




bytedawg at bytetamer.com wrote:
> I found this while cruising the internet for more ideas for my electric
> motorcycle.
> http://www.schultzengineering.us/build.htm
>
> marv
>
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