Something apparently is robbing my RPM's. HELP!

[Sir Nuke]

Originally Posted by yurtle

Invisible ink.

LOL and he may be getting a lump of coal in his stocking as well!!! LOL

[azTony]

just monitored the controller and it is seeing 100% throttle

rules that out. Not sure what to tell Robby now, he said to send the motor back and he will refund... then i have no motor

[cableguy_hd]

was this a bandit upgrade or a custom spec built motor? Just curious

Just reread your motor thread... 30mph with 30% torque increase on 48v...
These gurus know a lot more than me but could the brakes be dragging??

Also if you were getting 23mph on
36v what would be the % increase
on speed with this motor by gaining 30%
torque?

[bokeasmowl]

If you want a real motor contact DnD.

[bokeasmowl]

Maybe I shouldn't have responded like that since I've never ran a PQ motor. But after running DnD motors, why would I.

[sportcoupe]

I too have never run a PQ motor, only D&D. My neighbor ordered a custom PQ motor and after 6+ weeks of waiting, they didn't ship him what he ordered so this wouldn't be the first time that has happened here.

BTW, everytime I ordered a D&D I had it within 5 days, dyno tested with results and I always received exactly what I asked for.

[JohnnieB]

Originally Posted by azTony

just monitored the controller and it is seeing 100% throttle

rules that out. Not sure what to tell Robby now, he said to send the motor back and he will refund... then i have no motor

If you happen to have a set of stock wheels/tires you can put on the cart, let's find out what the max speed on 18" tall x 8.5" wide tires is.
That will give us the max RPM for the PQ motor at 48V.

Also, when speed testing, accelerate slowly to minimize battery pack voltage drop under load.
In addition, inflate tires to maximum safe air pressure.

[azTony]

I do not have stock tires to swap, bummer.

The tire pressure thing is what I had asked about and did a lot of searching on here. What is the safe tire pressure for running the "ATV" tires as they call them? Off the top of my head I think it says 8psi on the side wall.

Brakes are sounding like something else to look at.

[JohnnieB]

Brake and bearing drag is easy to check. Just push the cart by hand on a hard level surface.
It weighs about half a ton, so it takes some effort to get it moving, but once it is moving, it should be fairly easy to keep it moving.

The max pressure stamped on the tire is the maximum allowable pressure for the tire at its max load and max speed.
You may not be loading the tires (Gross weight of cart and passengers divided by number of tires on ground) near their max and the speed probable isn't anywhere near max either, so the number on the sidewall may be very conservative.

When a tire has weight on it, there is a flat spot on the bottom of the circle tho outer diameter forms. The lower the air pressure, the longer the flat spot and energy is used creating the flat spot as the tire rolls.

Figuring out the exact numbers would be complex to say the least, but for simplicity let's assume it takes 1 Ft/Lb of energy to create the flat spot.

A 26" tire rotates 877 each mile or 14.6 times for each MPH.
If a linear relationship exists, at 10 MPH, 146 Ft/Lb of torque is needed to turn the tire, at 20 MPH it is 292 Ft/Lb and at 30 MPH it is 438 Ft/Lb.
At some MPH, the torque needed to turn the tire, will equal the amount of torque the motor will generate and that is the top speed for that tire being turned by that motor.

Whether they are High-Torque, High-Speed or Standard performance motors, the traction motors used in golf carts, decrease in torque as RPM increase, so for maximum speed, you want minimum rolling resistance.

[yurtle]

You can kinda "eyeball" the tire pressure. If you've payed attention to car and motorcycle pressure, you kinda get a "feel" for it.