drive wheel setup opinions

[dcastillo]

this sections been dead a fews days so here goes....

Im still planning on getting dual motor independent drive wheels on my cart (as funding comes in )

I figure stage one is the wheels then the motors...

been looking all over for a good setup... seems I have a hard time getting things to match nicely (as in sprockets with dual flanges hubs with the right bolt pattern on the rim and then find a tire that fits) been giving myself a headache

finally came across this setup that seems good, although narrower then my current tires that are almost 6" wide.

http://www.northerntool.com/shop/tools/product_200331225_200331225
http://www.bmikarts.com/Sprocket-35-72T-2-1316-Bolt-Circle_p_1377.html

what do you guys think?

what are the pros/cons of going to a 4" tire from 6"?

the only mod I would need to do is chagne the bearings out since I need a 5/8 ID bearing...

On a separate note, is there a crude way to guestimate the power of my motor since Im undervolting it?
its a 2.5HP 90V but im only hitting it with 48V. normal accelerations draw 30-40A and pavement cruising is at 10A???

(Im trying to get an idea of what size motor I need to get the same power output, 800W, 1000W, etc)

thanx
danny

 

[itsid]

Well, you can guestimate the power;
you know what it draws (48V * 30A) up to (48V* 40A)
that is 1440 - 1920 Watts with a 'normal acceleration' and
48V * 10A = 480Watt at cruise speeds.

it's safe to assume that your motor has an efficiency rating of about 85% on low rpms and up to 90% at 'mid' rpms it then drops again, sometimes below 60%...
So you'll have a power output of ~435 Watts while cruising and about 1630 when accelerating.

I hope that's close enough as a guess

The thing is, to know exactly your power output you will have to either KNOW the efficiency at a certain rpm and voltage, or you'll need to measure the power (that involves a dyno).
So in most cases the power input and efficiency guestimation must suffice I'm afraid

And for the wheels, that depends, if your current wheels loose traction at WOT, this will get worse with narrower tires;
if they always provide full grip it's save to step down I'd say.

'sid

 

[dcastillo]

Thanx for the reply,
The numbers make sense math wise, where im confused is if i buy a my1020 1000W motor would it be more powerful? Is 1000w the most it can do, or what it can do continously?
Im just not sure how to compare the motors if that makes sense....
Thanx
Danny