High speed motors

[stuart29801]

Its series thats the one i really want be there will be 4 people on cart at times and wasnt sure if there would a torq problem with that high rpm motor. Also havent heard many talk about amd motors so wasnt sure about reliability

[Sir Nuke]

Originally Posted by stuart29801

Its series thats the one i really want be there will be 4 people on cart at times and wasnt sure if there would a torq problem with that high rpm motor. Also havent heard many talk about amd motors so wasnt sure about reliability

I too have the same motor as Yurtle......and I love it. and have hauled 4 people on my cart and have had no problem at all. I'm only at 36v.....but with my 23" tires and a 500 amp controller.....It gets up and runs, 27 mph all day long.

[yurtle]

I have stock tires and the motor in my sig. With 4 passengers it out runs every buggy in my hood. No problem with torque, since it has 6.1 Hp.

[JohnnieB]

Originally Posted by yurtle

I have stock tires and the motor in my sig. With 4 passengers it out runs every buggy in my hood. No problem with torque, since it has 6.1 Hp.

HP = Torque * RPM / 5252, so one motor can generate 6.1 HP while propelling a cart at 3 MPH and a different motor can generate 6.1 HP while propelling the same cart at 30 MPH.

In and of itself, HP is a poor yardstick for measuring motor performance since it is a calculated value based on two variables.
The amount of Torque produced at a specific RPM is what counts.

Your motor generates 6.1 HP @ 5330 RPM with a 48V battery pack and Torque = HP * 5252 / RPM, so it is producing 6.0 Ft/Lb at 5330 RPM.

That motor is most definitely wound for high speed.

[InVision]

I had a custom EMP motor built. D&D 170-506-0002 core. I got nearly ~70% increase in torque and stock gears with back seat was 35 mph. I had it setup with a different armature construction, with fewer conductors to help increase top speed but larger conductors and brush/commutator system to help handle higher currents. I had 500 amp FSIP controller 48v 2 ga... see signature. This was just awesome. With a series motor you need serious HD armatures because if you go 30 mph down a hill they will load up and burn out eventually.

M

[Sir Nuke]

Originally Posted by JohnnieB

HP = Torque * RPM / 5252, so one motor can generate 6.1 HP while propelling a cart at 3 MPH and a different motor can generate 6.1 HP while propelling the same cart at 30 MPH.

In and of itself, HP is a poor yardstick for measuring motor performance since it is a calculated value based on two variables.
The amount of Torque produced at a specific RPM is what counts.

Your motor generates 6.1 HP @ 5330 RPM with a 48V battery pack and Torque = HP * 5252 / RPM, so it is producing 6.0 Ft/Lb at 5330 RPM.

That motor is most definitely wound for high speed.

well not sure it makes a difference.....but our motors are rated at 6.1 HP at 5330 rpm using 36V not 48v

[JohnnieB]

Originally Posted by Sir Nuke

well not sure it makes a difference.....but our motors are rated at 6.1 HP at 5330 rpm using 36V not 48v

From what I understand, at 48V, the HP will be 1/3 higher at 5330 RPM, or about 8.1 HP and the Torque will be about 8.0 Ft/Lb.

The RPM at which peak HP is developed may shift also, and we don't know for certain if 5330 RPM is Peak HP at 36V. (I suspect it is, since advertised HP tends to be Peak HP. )

Warning: Technical Stuff.

Torque is proportional to Kilo-Watts and kW = A * V.
The dynamic impedance of the motor windings is determined by the Back-EMF being generated, which increases as RPM increase.
If the motor's impedance remains constant at a given RPM, a higher applied voltage would force more amps through the resistance, which would in turn increase the kW being delivered to the motor, thereby increasing the torque generated, which would increase the HP calculated for that RPM.

However, I'm not sure how a higher amp flow would effect the Back-EMF at a given RPM, so the effect of increasing the applied voltage may not linearly increase the torque at that RPM (and calculated HP).

If someone has the Torque or HP ratings for the same motor at the same RPM at two different voltages (IE: 36V and 48V), please chime in. That info would answer the question.

[Sir Nuke]

Originally Posted by JohnnieB

If someone has the Torque or HP ratings for the same motor at the same RPM at two different voltages (IE: 36V and 48V), please chime in. That info would answer the question.

well I do have this......

[JohnnieB]

That indicates the motor, with 36V applied, produces 6.1 HP @ 4600 RPM rather than @ 5330 RPM.

It also says it has 10 HP peak with a stock controller, but doesn't give the RPM at which Peak HP is developed.

Peak HP tends to be at an RPM that coincides with a point halfway between Stalled Torque and No Load RPM on the Torque vs RPM curve. (See attached)

So that motor will develop 6.1 HP at two RPM points, one above and one below the Peak HP RPM.

How the motor is wound (IE: for Speed or for low end Torque) essentially changes the downward angle of the hypotenuse on the graph, but not its length and in very general terms, what is gained in RPM is lost in Torque, and vice versa.

When you up the voltage, you move the downward sloping line to the right further, lengthening the hypotenuse, giving you more low end torque as well as a higher no load RPM.

FWIW: The torque vs RPM curve for a sepex motor, in and of itself, looks about the same as one for a series wound motor, but it can be altered into something other than basically a straight line by Field Mapping.

[Sir Nuke]

WELL All I really know is this...... I took my newly purchased cart a year ago, which had a totally stock drive system and 23" tires on it, which would max out at 12 to 13 mph. I totally replaced my drive system with an ALLTRAX SPM-48500 Controller, HD F&R Switch, 400A SD Solenoid, 2 Ga. Cables, AMD 7126 "RAPTOR" Motor......and now it runs 27 mph all day long! lol and I love it. and that is on 36v as well.