Robot Motors



AmpFlow high-performance A28 motors are designed to give the highest level of performance possible in a brushed DC motor. This is achieved by advanced design and the use of neodymium rare-earth magnet material.

New fan-cooled A28 motors are designed for applications that require longer duty cycles and even higher power outputs. Low profile leads enable more compact installations. Available for 24V and 48V.

High-Performance Electric Motors
The mid-range F30 motors are designed for the highest performance and efficiency while still using the less expensive ferrite magnets. The economy E30 motors are designed to give good performance at the lowest possible price.

All motors on this page are available with the optional AmpFlow speed reducer.

Custom motors are available with a minimum order of 25 units.

Type High-Performance Mid-Range Economy
Model A28-400 A28-150 F30-400 F30-150 E30-400 E30-150
Diameter (inches) 3.0 3.0 3.1 3.1 3.1 3.1
Length (inches) 6.7 4.0 6.7 4.0 5.8 4.0
Peak HP 4.3 3.0 2.5 2.3 2.1 1.0
Stall Torque (oz-in) 3560 1950 2240 1370 1500 710
Efficiency 83% 80% 84% 82% 79% 76%
Nominal Voltage* 24V* 24V* 24V* 24V* 24V* 24V*
RPM @ 24V 4900 6100 4500 6900 5700 5600
Shaft Dia. (inches) 1/2 1/2 1/2 1/2 1/2 1/2
Shaft Length (inches) 2.0 2.0 2.0 2.0 2.0 2.0
Keyway (inches) 1/8 1/8 1/8 1/8 1/8 1/8
Capacitors Yes Yes Yes Yes No No
Magnet Type Neodymium Neodymium Ferrite Ferrite Ferrite Ferrite
No Load Amps 4.4 4.4 2.1 2.5 3.2 2.1
Resistance (Ohms) 0.044 0.064 0.076 0.081 0.089 0.190
Kt (oz-in/Amp) 6.58 5.26 7.17 4.66 5.63 5.70
Kv (RPM/Volt) 205 257 189 287 240 237
Weight (pounds) 6.9 3.8 8.3 4.7 5.9 3.6
Price $449 $344 $289 $239 $109 $79
Pictures A28-400 A28-150 F30-400 F30-150 E30-400 E30-150
Drawings A28-400 A28-150 F30-400 F30-150 E30-400 E30-150
Performance Charts A28-400 A28-150 F30-400 F30-150 E30-400 E30-150

* The above specifications are for 24V. The motors can also be used at 12V or 18V. The RPM is proportional to the voltage so running at 12V will result in half the no-load RPM that is shown above for 24V. The lower voltage also reduces the maximum achievable torque by 50%. The motors have also been tested and used at higher voltages resulting in higher RPM, torque, and power. Shorter duty-cycles are recommended for higher voltages to allow the motors time to cool. Please note that the above torque figures are the theoretical peak torques when stalled. Operating any high-performance motor while stalled will damage it.

NEW! Fan-cooled motors

Type Fan Cooled  24V Fan Cooled 48V
Model A28-400-F24 A28-150-F24 A28-400-F48 A28-150-F48
Diameter (inches) 3.0 3.0 3.0 3.0
Length (inches) 7.8 5.1 7.8 5.1
Peak HP 4.3 3.0 11.5* 4.6
Stall Torque (oz-in) 3560 1950 7260** 2500
Efficiency 83% 80% 85% 82%
Nominal Voltage 24V 24V 48V 48V
RPM at Nominal Voltage 4900 6100 6400 7400
Shaft Dia. (inches) 1/2 1/2 1/2 1/2
Shaft Length (inches) 2.0 2.0 2.0 2.0
Keyway (inches) 1/8 1/8 1/8 1/8
Capacitors Yes Yes Yes Yes
Magnet Type Neodymium Neodymium Neodymium Neodymium
No Load Amps 4.4 4.4 4.4 2.5
Resistance (Ohms) 0.044 0.064 0.066 .165
Kt (oz-in/Amp) 6.58 5.26 10.05 8.70
Kv (RPM/Volt) 205 257 135 156
Weight (pounds) 7.2 4.0 7.3 4.0
Price $499 $394 $499 $394
Pictures A28-400-F24 A28-150-F24 A28-400-F48 A28-150-F48
Performance Charts A28-400-F24 A28-150-F24
Pre Order***

The fan-motors have ventilation holes in the front and rear aluminum plates to allow for flow-through cooling. The holes in the front plate are positioned so they are not blocked when mounting the motor to a flat surface. These motors also feature low-profile motor leads for better fit into smaller spaces.

* Theoretical peak power is 11.5 HP. Power at the recommended short-term current limit of 200A is 9.1 HP.
** The current required to reach 7260 oz-in is far outside the safe operating limits of this motor. This figure is theoretical and should be used for comparative purposes only.
*** Available for pre-order now. Estimated shipping date is 1/15/16. Credit cards will not be charged until motor is shipped.

Recommended 48V motor speed controllers from IFI will be available soon. Please contact us by email to be notified when the controllers become available:


Getting high efficiency from a low-voltage motor is not easy. There are many factors that effect efficiency. We have optimized each of these factors to achieve very high efficiency in these motors.

Type High-Performance Mid-Range Economy
Model A28-400 A28-150 F30-400 F30-150 E30-400 E30-150
Peak Efficiency (PE) 83% 80% 84% 82% 79% 76%
RPM at PE 4500 5500 4200 6300 5100 5000
Torque at PE (oz-in) 300 190 170 120 145 85
Horsepower at PE 1.3 HP 1.0 HP 0.71 HP 0.74 HP 0.75 HP 0.40 HP
Current at PE 50 Amps 40 Amps 26 Amps 28 Amps 29 Amps 17 Amps
HP Range for 75%+ Efficiency 0.5 to 2.9 0.5 to 1.8 0.2 to 1.7 0.3 to 1.6 0.4 to 1.3 0.3 to .5

Type Fan Cooled  24V Fan Cooled 48V
Model A28-400-F24 A28-150-F24 A28-400-F48 A28-150-F48
Peak Efficiency (PE) 83% 80% 85% 82%
RPM at PE 4500 5500 6000 6750
Torque at PE (oz-in) 300 190 510 220
Horsepower at PE 1.3 HP 1.0 HP 3.0 HP 1.5 HP
Current at PE 50 Amps 40 Amps 55 Amps 28 Amps
HP Range for 75%+ Efficiency 0.5 to 2.9 0.5 to 1.8 1.0 to 8.1 0.6 to 3.1

As you can see from the above charts, the efficiency of the motors is very high over a broad range of power.

Sprockets and Keys


The 1/2-inch bore of our standard sprocket fits all our 3-inch motors.

The sprocket has 9 teeth and it works with #35 roller chain. It comes with a 1/8-inch key.

Sprocket - $14      Quantity

The motors are warranted to be free from manufacturing defects, and fully operational when you receive them. AmpFlow gives no other warranty, either expressed or implied. Warranties are not transferable. In no event shall AmpFlow's liability exceed the buyer's purchase price, nor shall AmpFlow be liable for any indirect or consequential damages.

Shipments must be to a street address; we can not ship to a PO Box. Please allow 7-10 days for orders shipped by UPS ground, 3-4 days for orders shipped by 2nd day air, and up to 14 days for international orders.

  We accept Visa, MasterCard, and PayPal.

Replacement fans and brushes are available here

Contact us for custom motors and volume pricing.

"That's a beautiful motor! Wow. Good work. Great price. This should become standard equipment for all large robots."
          --Edwin Wise.   Mad Scientist and author of Applied Robotics

"Very powerful. Too fast on 24 Volts even with poor batteries."
          --Mike Schreiber.  Builder of the Electri-Flyer electric bicycle.

"BattleBot participants are constantly trying to make their robots quicker, stronger and faster. With nearly four horsepower and 3840 oz-in torque, the 11.9-pound A40 motor is ideally designed for our larger robots. Since power is often the deciding factor in BattleBot competitions, more and more participants are selecting these motors to power their robots with a lightweight, high-efficiency motor that provides plenty of power on demand."
Trey Roski.   CEO of BattleBots.

"As the first motors designed specifically for robotic combat, these motor perform fabulously! They combines incredible power and some of the best features you could ask for when looking for a high-end motor for a BattleBot. They are the most powerful and finest constructed DC permanent magnet motors that I've ever used. I chose this motor for the weapon motor in Nightmare and I am definitely a very satisfied customer!"
          --Jim Smentowski.    BattleBots Champion (Nightmare, Backlash)

"This motor packs a lot of power into a light-weight package. They give Minion the power it needs and I still have weight to spare!"
          --Christian Carlberg.    BattleBots Champion (Team Cool Robots)

"Get the best motors you can afford. Good motors are the foundation upon which all else rests. People can win with hokey electronics or even with inoperative weapons, but good motors make good robots."
          --William Gurstelle.    Author of Building Bots : Designing and Building Warrior Robots

"We were extremely pleased with the performance of the motors in our middleweight Heavy Metal Noise at BB 4.0. The motor supplied an insane amount of energy to our kinetic disk weapons. Time to spinup was minimal and after combat the motor was never more than mildly warm to the touch."
          --Jay Johnson.    BattleBots Competitor (Big Bang Robotics)

"I've been building robots as a hobby for about 30 years and this is definitely one of the best motors (power, weight, cost, quality), that I've ever encountered. Since I've never built a 'BattleBot' before, I decided to focus most of my attention on other aspects of the design and having this motor meant that I didn't have to spend many hours 'tweaking' an inferior motor just be competitive."
          --Billy Moon.    BattleBots Competitor

"I can attest to their super high quality of craftsmanship and design. We tested them with a few different controllers and monitored the results using a Tektronix digital scope and a digital ammeter. Results: This is the largest motor we have tested and amazingly it had the cleanest feedback signal of any motor yet. Generally the higher the quality of motor mechanics, windings, brush and commutator, the cleaner this signal is. This means these motors are less likely to blow a speed controller due to transient voltage spikes.
          These motors are VERY well built. We saw no appreciable heat up in the testing we did. We did a lot of stall and near stall testing. These are amazing motors and are ridiculously powerful."
Alexander Rose.      BattleBots Champion (Toro, T-minus, Matador)

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