# DC Motor - Stall Calculations

Discussion in 'General Electronics Chat' started by rlm42, Oct 3, 2013.

1. ### rlm42 Thread Starter New Member

Feb 16, 2013
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0
Hey guys, i'm having trouble calculating the stall masses of a dc motor lifting various loads with a maximum output speed of 80 rpm and rated voltage 6V ..

I've done most of the calculations, i just don't understand how to calculate the stall mass as this will change for different supply voltages correct? How would I calculate this for something other than the rated voltage where I don't know the output torque etc. The formulas I am using just don't make sense.. See attached spreadsheet.

I need it to stall at around 1.5kg, but must be able to lift 0.5kg and 1kg..

Any help would be great!
Thanks.

Last edited: Oct 4, 2013
2. ### shortbus AAC Fanatic!

Sep 30, 2009
4,096
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"Stall", is also known as "locked rotor". Don't know how that would relate to your question though.

3. ### rlm42 Thread Starter New Member

Feb 16, 2013
10
0
That doesn't really help

4. ### MaxHeadRoom Expert

Jul 18, 2013
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2,524
Are you looking for the continuous stall torque value? Lb-in/ Nm?
Max.

5. ### THE_RB AAC Fanatic!

Feb 11, 2008
5,435
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The stall torque as you expressed it depends on motor torque, which depends on the DC motor's armature current (assuming a standard PM DC motor).

So if you limit the max current to X, it will lift a 1kg load but stall (or go backwards) with a 1.5kg load.

To find X you use a variable DC powersupply, and an ammeter. Then see how much current is required to lift 1kg, and set the max current slightly higher than that.

Then (obviously) your DC motor driver circuit needs to have a max current limit, set to X amps.

6. ### shortbus AAC Fanatic!

Sep 30, 2009
4,096
1,692
Most people don't do things like your trying to do.

A torque limiting disc/clutch is the normal way of doing something like this. Easier on the motor windings and driver.