MP 12V Motor with 48 CPR Encoder for 25D mm Metal Gearmotors (No Gearbox)

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Pololu item #: 4860
Brand: Pololu
Status: Active and Preferred 
RoHS 3 compliant


This is the motor and encoder portion of our medium-power (HP), 12V 25D mm metal gearmotors with 48 CPR encoders. It does not include a gearbox, but the pinion gear on the output shaft works with all of our 25D mm gearmotor gearboxes, so this can be used as a replacement motor or encoder for those gearboxes.

Key specifications:

voltage no-load performance stall extrapolation
12 V 8200 RPM, 100 mA 0.17 kg⋅cm (2.4 oz⋅in), 1.8 A

You can use the following selection boxes to choose from all of our 25D metal gearmotor versions:

Alternatives available with variations in these parameter(s): gear ratio motor type encoders? Select variant…

Compare all products in 12V Medium-Power (MP) 25D mm Gearmotors.

Pictures

25D mm motor with 48 CPR encoder (no gearbox).

25D mm motor with 48 CPR encoder (no gearbox).

25D mm motor with 48 CPR encoder (no gearbox), shown with end cap removed.

25D mm metal gearmotor with 48 CPR encoder (with end cap removed).

The 25D and 37D mm metal gearmotors with encoders have cables that are terminated with a 6-pin, 0.1″-pitch female connector.

Encoder A and B outputs for 25D mm HP 6V metal gearmotor with 48 CPR encoder (motor running at 6 V).




Overview

This motor with integrated 48 CPR (counts per revolution) quadrature encoder is intended as a replacement medium-power (MP) 12 V motor with encoder for our 25D mm metal gearmotors. It is intended for use at 12 V, but in general, these kinds of motors can run at voltages above and below this nominal voltage. Lower voltages might not be practical, and higher voltages could start negatively affecting the life of the motor.

The output shaft has a non-removable pinion gear that works with all of our 25D mm gearmotor gearboxes. Note that we do not sell the 25D mm gearboxes separately, but if you have a gearmotor with a damaged motor or encoder (or if you want to effectively add an encoder to a version without an encoder), you can transfer the gearbox to this replacement motor.

The motor has a diameter of 24.2 mm (0.95 in) and a length of approximately 43 mm (1.7 in) from the top of the motor can to the bottom of the encoder. The top of the motor has two mounting holes threaded for M3 screws. These mounting holes are 17 mm apart and form a line with the motor shaft at the center. The mounting holes have a depth of approximately 2 mm.

Other motor windings with identical dimensions and pinion gears are also available, resulting in five total options:

These motors are functionally identical to the previous versions we carried without end caps (they use the same motor and encoder). The black plastic end cap is easily removable if you need to access the encoder or want to slightly reduce the overall motor size, but there is a little bit of base plastic that will remain, as shown in the picture below:

Pinion gear specs

Gearmotor options

You will typically want to combine this motor with a gearbox to give it a more appropriate combination of torque and speed (without a gearbox, it offers very high speed with very low torque). The MP 12V versions of our 25D mm metal gearmotors consist of this motor combined with different gearboxes. We do not carry the gearboxes by themselves, so unless you are looking at this as a replacement motor for a compatible gearbox you already have, we strongly recommend you consider getting a preassembled gearmotor with the gear ratio that best suits your project requirements.

Rated
Voltage		 Motor
Type		 Stall
Current		 No-Load
Current		 Gear Ratio No-Load Speed
(RPM)		 Extrapolated
Stall Torque		 Max Power
(W)

Without Encoder

With Encoder
(kg ⋅ cm) (oz ⋅ in)
12 V High-Power
(HP)		 5.0 A 250 mA
w/o
encoder


300 mA
with
encoder		 1:1 (no gearbox) 10,000 0.4 5.5 10 – item #4840
4.4:1 2200 1.7 24 9.4 item #3201 item #4841
9.7:1 1000 3.9 54 10 item #3202 item #4842
20.4:1 500 7.4 100 9.4 item #3203 item #4843
34:1 300 11 150 8.9 item #3204 item #4844
47:1 220 15 210 8.4 item #3205 item #4845
75:1 130 22 310 – item #3206 item #4846
99:1 100 29 400 – item #3207 item #4847
12 V Medium-Power
(MP)		 1.8 A 80 mA
w/o
encoder


100 mA
with
encoder		 1:1 (no gearbox) 8200 0.17 2.4 3.5 – item #4860
4.4:1 1800 0.71 10 3.2 item #3225 item #4861
9.7:1 800 1.7 24 3.4 item #3226 item #4862
20.4:1 380 3.2 44 3.1 item #3227 item #4863
34:1 230 4.7 65 2.8 item #3228 item #4864
47:1 170 6.4 89 2.8 item #3229 item #4865
75:1 100 8.5 120 2.3 item #3230 item #4866
99:1 79 11 150 2.3 item #3231 item #4867
172:1 46 18 250 2.1 item #3232 item #4868
227:1 35 24 330 – item #3233 item #4869
12 V Low-Power
(LP)		 0.9 A 50 mA
w/o
encoder


60 mA
with
encoder		 1:1 (no gearbox) 5600 0.14 1.9 1.8 – item #4880
4.4:1 1200 0.53 7.4 1.7 item #3249 item #4881
9.7:1 580 1.3 18 1.8 item #3250 item #4882
20.4:1 280 2.4 33 1.7 item #3251 item #4883
34:1 170 3.7 51 1.6 item #3252 item #4884
47:1 120 4.8 67 1.4 item #3253 item #4885
75:1 75 7.1 99 1.4 item #3254 item #4886
99:1 57 8.7 120 1.2 item #3255 item #4887
172:1 33 13 180 1.1 item #3256 item #4888
227:1 25 16 220 1.0 item #3257 item #4889
378:1 15 23 320 – item #3258 item #4890
6 V High-Power
(HP)		 6.0 A 420 mA
w/o
encoder


500 mA
with
encoder		 1:1 (no gearbox) 10,000 0.3 4 7 – item #4800
4.4:1 2200 1.2 17 6.7 item #1570 item #4801
9.7:1 1000 2.3 32 5.9 item #1571 item #4802
20.4:1 480 4.8 67 5.9 item #1572 item #4803
34:1 290 6.8 94 5.1 item #1573 item #4804
47:1 210 9.1 130 4.9 item #1574 item #4805
75:1 130 14 190 4.5 item #1575 item #4806
99:1 99 15 210 3.9 item #1576 item #4807
172:1 57 27 380 – item #1577 item #4808
6 V Low-Power
(LP)		 2.0 A 100 mA
w/o
encoder


120 mA
with
encoder		 1:1 (no gearbox) 6200 0.15 2.1 2.1 – item #4820
4.4:1 1300 0.63 8.7 2.1 item #1581 item #4821
9.7:1 630 1.3 18 1.9 item #1582 item #4822
20.4:1 290 2.5 35 1.9 item #1583 item #4823
34:1 180 3.9 54 1.7 item #1584 item #4824
47:1 130 4.8 67 1.5 item #1585 item #4825
75:1 80 7.5 100 1.5 item #1586 item #4826
99:1 61 9.1 130 1.4 item #1587 item #4827
172:1 35 14 190 1.2 item #1588 item #4828
227:1 27 17 240 1.1 item #1589 item #4829
378:1 16 25 350 – item #1590 item #4830
499:1 12 31 430 – item #1591 item #4831

Note: The listed stall torques and currents are theoretical extrapolations; units will typically stall well before these points as the motors heat up. Stalling or overloading gearmotors can greatly decrease their lifetimes and even result in immediate damage. The recommended upper limit for continuously applied loads is 4 kg⋅cm (55 oz⋅in), and the recommended upper limit for intermittently permissible torque is 8 kg⋅cm (110 oz⋅in). Stalls can also result in rapid (potentially on the order of seconds) thermal damage to the motor windings and brushes; a general recommendation for brushed DC motor operation is 25% or less of the stall current.

25D mm metal gearmotor with 48 CPR encoder (with end cap removed).

Using the encoder

A two-channel Hall effect encoder is used to sense the rotation of a magnetic disk on a rear protrusion of the motor shaft. The quadrature encoder provides a resolution of 48 counts per revolution of the motor shaft when counting both edges of both channels. To compute the counts per revolution of the gearbox output, multiply the gear ratio by 48. The motor/encoder has six color-coded, 11" (28 cm) leads terminated by a 1×6 female header with a 0.1″ pitch, as shown in the main product picture. This header works with standard 0.1″ male headers and our male jumper and precrimped wires. If this header is not convenient for your application, you can pull the crimped wires out of the header or cut the header off. The following table describes the wire functions:

Color Function
Red motor power (connects to one motor terminal)
Black motor power (connects to the other motor terminal)
Green encoder GND
Blue encoder Vcc (3.5 – 20 V)
Yellow encoder A output
White encoder B output

The Hall sensor requires an input voltage, Vcc, between 3.5 and 20 V and draws a maximum of 10 mA. The A and B outputs are square waves from 0 V to Vcc approximately 90° out of phase. The frequency of the transitions tells you the speed of the motor, and the order of the transitions tells you the direction. The following oscilloscope capture shows the A and B (yellow and white) encoder outputs using a motor voltage of 6 V and a Hall sensor Vcc of 5 V:

Encoder A and B outputs for 25D mm HP 6V metal gearmotor with 48 CPR encoder (motor running at 6 V).

By counting both the rising and falling edges of both the A and B outputs, it is possible to get 48 counts per revolution of the motor shaft. Using just a single edge of one channel results in 12 counts per revolution of the motor shaft, so the frequency of the A output in the above oscilloscope capture is 12 times the motor rotation frequency.

Selecting the right gearmotor

We offer a wide selection of metal gearmotors that offer different combinations of speed and torque. Our metal gearmotor comparison table can help you find the motor that best meets your project’s requirements.

Dimensions

Size: 25D x 46L mm1
Weight: 60 g

General specifications

Gear ratio: 1:12
No-load speed @ 12V: 8200 rpm3
No-load current @ 12V: 0.10 A4
Stall current @ 12V: 1.8 A5
Stall torque @ 12V: 0.17 kg·cm5
Max output power @ 12V: 3.5 W
No-load speed @ 6V: 4100 rpm6
Stall current @ 6V: 0.90 A6
Stall torque @ 6V: 0.085 kg·cm6
Motor type: 12V, 1.8A stall (MP 12V)
Lead length: 8 in7
Encoders?: Y

Notes:

1
Length does not include the motor shaft. See dimension diagram for details.
2
This motor does not have a gearbox.
3
Typical; ±20%.
4
Typical, ±50%; no-load current depends on internal friction, which is affected by many factors, including ambient temperature and duration of motor operation.
5
Stalling is likely to damage the motor. Stall parameters come from a theoretical extrapolation of performance at loads far from stall. As the motor heats up, as happens as it approaches an actual stall, the stall torque and current decrease.
6
This motor will run at 6 V but is intended for operation at 12 V.
7
May vary by a few inches.

File downloads

Frequently-asked questions

Is it okay to stall this motor at its operating voltage?

No! Stalls can result in rapid (potentially on the order of seconds) thermal damage to the motor windings and brushes; a general recommendation for brushed DC motor operation is 25% or less of the stall current, which means keeping continuously applied loads around 25% or less of the stall torque.

Additionally, for many of our gearmotors with high gear ratios, the extrapolated stall torque is beyond what the gearboxes are designed to handle, and a stall could instantly damage the gears. Make sure to keep applied loads within the published limits for your gearmotor.

What do the dotted lines mean in the motor performance curves from the datasheet?
In our motor performance curves, the solid lines show the regions where we actually took measurements while the dotted lines show extrapolations beyond that. For many motors, we took measurements out to about 50% of the stall torque, since continued operation at loads past this point increasingly risk thermal damage to the windings. However, for higher gear ratios, going to 50% of the stall torque exceeds what is safe for the gearbox, so the measurements are further limited to not much past our recommendation for continuously applied loads.

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