Quote:
Originally Posted by Ken Fry
...30% grade is a reasonable minimum hill climbing capability. So, you will want a tractive force of 1500 lbs. ...
|
I'm aiming a bit lower than that. None of the roads this commuter (if I get a range long enough to drive to work) will see will be steeper than 3%.
A 40 HP electric motor rated at 1770 rpm is about 120 foot-lbs of torque. From the specs on the motor, it peaks at 220% rated torque or 264 foot-lbs, but that assumes that it is starting from 0 rpm and the motor is started 'across the line' with a starter and a utility pumping up to 10 times rated current through it. I think I can reach 264 foot-lbs with a VFD and about 3 times rated current, or under 120 amps.
With the 3.43 ratio and 205/65 r14s (I measure them just under 30 inches in diameter so I use 15 inch radius) that will give me about 725 pounds of force to the road.
There's a lot of assumptions wrapped up in there. I'll see what I have when I get there. And I'll have some fun measuring everything along the way.