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Old 07-28-2017, 02:26 PM   #1
nosaj2
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Default AMD Raptor high claims conflicting information

So I see this everywhere about the AMD RAPTOR.

E-Z-GO AMD 7126 6.1 Non-Peak HP @ 5330 Rpm, 36 Volt, 25 Mph, (High Speed & Torque - "The Raptor") DC Electric Motor

Then when you read the fine print you see this. "This motor will provide a significant boost in speed, but will lose some overall low end torque."

Seems misleading to me. Has anyone had any experience with these motors?
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Old 07-28-2017, 02:34 PM   #2
cgtech
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Default Re: AMD Raptor high claims conflicting information

Tons. It is not a "torque" motor for building a offroad cart. It is designed for street speed. Not that it's any sort of lazy bum in the low end torque department (I built a Yami Drive "series conversion" that will lift the front wheels off the ground, with a 800a controller). They are trying to keep off-roaders from buying it, because I also know from experience it will die in that application. Also, a 400a controller is minimum requirements for that motor to perform, and not kill the controller.
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Old 07-28-2017, 10:22 PM   #3
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Default Re: AMD Raptor high claims conflicting information

Quote:
Originally Posted by nosaj2 View Post
So I see this everywhere about the AMD RAPTOR.

E-Z-GO AMD 7126 6.1 Non-Peak HP @ 5330 Rpm, 36 Volt, 25 Mph, (High Speed & Torque - "The Raptor") DC Electric Motor

Then when you read the fine print you see this. "This motor will provide a significant boost in speed, but will lose some overall low end torque."

Seems misleading to me. Has anyone had any experience with these motors?
There are at least 2 of us here that are running that motor....myself and yurtle. My cart, you can see the specifics in my sig, does exacly what the description said....and that is at 36v.....put 48v to it and tack on a 30% jump to those numbers.....as long as you can supply the motor with the "juice".
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Old 07-29-2017, 01:18 AM   #4
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Default Re: AMD Raptor high claims conflicting information

I guess I went a little over the top in my response. It will make a 36v Ezgo with stock tires into about a 25 mph machine. But would need the factory available HD 400a controller as a starting point, not the controller found in most carts. We ordered many stock carts with h the HD upgrade, then installed that motor. The main difference was a Curtis 400a controller and 4ga cables from the factory.
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Old 07-29-2017, 01:01 PM   #5
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Default Re: AMD Raptor high claims conflicting information

Quote:
Originally Posted by nosaj2 View Post
So I see this everywhere about the AMD RAPTOR.

E-Z-GO AMD 7126 6.1 Non-Peak HP @ 5330 Rpm, 36 Volt, 25 Mph, (High Speed & Torque - "The Raptor") DC Electric Motor

Then when you read the fine print you see this. "This motor will provide a significant boost in speed, but will lose some overall low end torque."

Seems misleading to me. Has anyone had any experience with these motors?
I suspect the misleading issue is the advertising hyperbole says High Speed & Torque is one place and it says you lose some low end torque in another.

In very general terms, a series motor can be wound for high-speed OR it can be wound for high-torque, but it cannot be wound for high-speed and high-torque.

In a nutshell, for a high-speed motor the magnetic field generated by the field (stator) windings are relatively weak when compared to the magnetic field generated by the armature winding. Conversely, the magnetic field generated by the field windings of a high-torque motor are relatively strong when compared to the magnetic field generated by the armature windings.

In other words, if you wind for speed you lose low end torque and if you wind for torque, you lose high end speed. The stock motors typically used in carts are a compromise of the two extremes.


However, if you use physically bigger armature and field windings, you can build a motor with more speed than a stock motor and still have roughly the same torque as a stock motor, or a motor with more torque and about stock speed.

The AMD 7126 is an inch or so longer than a stock motor and even though it has a lot higher speed, it probably only has slightly less than stock torque.

As CG says, it is for an on-road cart rather than an off-road one and it needs to be fed properly to maximize its performance.
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Old 07-30-2017, 09:08 PM   #6
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Default Re: AMD Raptor high claims conflicting information

"high speed" and "high torque" are such relative terms. I wish they were spec'd out in a more logical way in relation to 36vdc and 48vdc. max rpm, HP, ft-lbs. "high" is very subjective. I don't want 25mph. but I do want 18-20mph I would like to dump the rest of that potential into torque. So in the terms of the marketing gurus, I want 50% more speed and 50% more torque.
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Old 07-31-2017, 10:49 AM   #7
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Default Re: AMD Raptor high claims conflicting information

Quote:
Originally Posted by nosaj2 View Post
"high speed" and "high torque" are such relative terms. I wish they were spec'd out in a more logical way in relation to 36vdc and 48vdc. max rpm, HP, ft-lbs. "high" is very subjective. I don't want 25mph. but I do want 18-20mph I would like to dump the rest of that potential into torque. So in the terms of the marketing gurus, I want 50% more speed and 50% more torque.
I share your wish.

I would love to see the Speed/Torque curves for motors published so we could compare apples to apples when trying to pick a specific motor for a specific cart.

Fortunately, some motor companies do provide halfway decipherable info that can be useful when decoded. RPM and Torque (expressed in ft/lb or any of the other units of measurement of torque) are empirical values while HP is a calculated value (HP = RPM times ft/lb divided by 5252), so if you have HP plus one of the other values, you can calculated the third, but that only provides one data point and several are needed to make a comparison.

Looking at the description of your setup, 2003 EZGO TXT - 36 volt USBattery - Stock Series Motor - Alltrax SR48500 - 400A Super Duty Solenoid - SW202 FnR - 2 AWG Welding cable - 20inch Tires - 12mph/gps - Powerwise Charger - Green I see two red flags waving.

First, your batteries might not be getting fully charged. The ferroresonant transformer type Powerwise charge you have is designed to charge Trojan batteries (and clones) while you have US Battery batteries, which require a higher on-charge voltage to reach 100% SoC. SoC chart provided by US Battery attached.

Second, 20" tall tires and 12MPH top speed on level ground. The typical top speed for EZGO TXT Series drive cart with a 36V battery pack, stock motor and stock height (18") tires is 14MPH. The mathematical speed gain going to 20" tires is 11.1% with a 10.0% torque loss. Theoretically the speed would be 15.6MPH, but due to the torque loss it will probably be about 15.2MPH.

Since you are only getting 12MPH and the cables, solenoid, F/R contactors and controller listed are good ones, I suspect you have low pressure tires (Max inflation pressure <10PSI), which take more torque to turn and slows the cart's top speed. If not, there is a problem with your amp delivery system, or motor.
Attached Images
File Type: jpg US Battery SoC vs OCV table from USB.jpg (145.6 KB, 0 views)
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Old 07-31-2017, 03:58 PM   #8
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Default Re: AMD Raptor high claims conflicting information

While watching the live monitor in the Alltrax software, my motor never pulls more than 200 amps. Even going up hill.
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Old 07-31-2017, 04:46 PM   #9
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Default Re: AMD Raptor high claims conflicting information

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Originally Posted by nosaj2 View Post
While watching the live monitor in the Alltrax software, my motor never pulls more than 200 amps. Even going up hill.
The max amps a motor can draw is inversely proportional to the RPM it is spinning at.

If your cart was moving faster than about 2.4MPH (motor spinning about 500RPM), the motor could not draw the max amps the batteries can produce, the controller can pass and the high current cables and contacts system can deliver.

Try WOT from a standing still a few feet up from the bottom of the hill, instead of flying start at the bottom of the hill.

Max amps will be drawn as the cart accelerates from zero up to about 1 or 2 MPH and will taper off as it continues to accelerate.

If programmed for it, your SR48500 has a peak throughput of 575A, but I doubt a stock motor is capable of drawing that many amps @36V even with a max effort takeoff on a steep incline, but it might exceed 300A.


Save a data log file and check what the battery voltage is dropping to when the motor is drawing whatever its max amps are.
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Old 07-31-2017, 09:49 PM   #10
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Default Re: AMD Raptor high claims conflicting information

Thanks JohnnieB!
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