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

Pololu item #: 4840 13 in stock
Brand: Pololu
Status: Active and Preferred 
RoHS 3 compliant
 Free shipping in USA 

Price break Unit price (US$)
1 23.95
10 21.56


backorders allowed

This is the motor and encoder portion of our high-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 10200 RPM, 150 mA 0.4 kg⋅cm (5.5 oz⋅in), 5.6 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…

 Description Specs (13) Pictures (5) Resources (4) FAQs (1) On the blog (0) 
I need additional information about this motor; do you have a datasheet?

No; the information we have available for this motor can be found on its product page. However, you can approximate various additional motor parameters from the information found in the “Specs” tab.

The electrical resistance of the motor can be approximated by dividing the rated voltage by the stall current (at the rated voltage). The electromotive force constant (Ke) can be approximated by dividing the rated voltage by the free-run speed (at the rated voltage). To approximate the motor torque constant (Kt), you can divide the stall torque by the stall current.

For pretty much any DC motor, the current, speed, power, and efficiency curves as a function of torque will look like those in the graph below (assuming motor voltage and temperature are constant):

The current and speed curves are approximately linear, and the product pages for our motors provide the approximate end points for these lines: (0 torque, no-load current) and (stall torque, stall current) for the red line, and (0 torque, no-load speed) and (stall torque, 0 speed) for the blue line.

The orange output power curve is the product of the speed and the torque, which results in an inverted parabola with its peak at 50% of the stall torque.

The green efficiency curve is the output power divided by the input power, where the input power is current times voltage. The voltage is constant, so you can divide the output power curve by the current line to get the general shape of the efficiency curve, which in turn lets you identify the torque, speed, and current that correspond to max efficiency.

There are many programs out there that you can use to generate these curves. For example, if you have access to MATLAB, you can use this customer-created MATLAB script to generate these motor plots for you from the specifications we provide for each gearmotor.

Note: A good general rule of thumb is to keep the continuous load on a DC motor from exceeding approximately 20% to 30% of the stall torque. Stalling gearmotors can greatly decrease their lifetimes, occasionally resulting in immediate damage to the gearbox or thermal damage to the motor windings or brushes. Do not expect to be able to safely operate a brushed DC gearmotor all the way to stall. The safe operating range will depend on the specifics of the gearmotor itself.

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Related Categories

12V High-Power (HP) 25D mm Gearmotors
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