Mabuchi RS-555PH-3255 has a rated voltage of 12 volts and full-load current of 2.4 amps and a stall current of 11.8 amps, does that mean it can generate 132 watts?

 

Mabuchi RS-555PH-3255 has a rated voltage of 12 volts and full-load current of 2.4 amps and a stall current of 11.8 amps, does that mean it can generate 132 watts?

No. Where did you come up with that number.

 

No. Where did you come up with that number.

Power = voltage x current. So how do i calculate maximum output power based on current and voltage?

 

Stall current is when the motor isn’t turning! It is consuming that power, not generating it!

I lt could possibly generate something close to 12x2.4 = 28.8W.

 

A motor can be operated above full load current. 10 amps is less than the stall current, which is 11.8 amps. I know if you operate it above full load current, it'll overheat and possibly damage the motor, but i am trying to calculate maximum possible power output.

 

So how do you calculate maximum possible output?

 

I mean how do you calculate maximum possible power output in watts, based on current and voltage?

 

What you get out of a motor is shaft power. AND for short times that can be possibly several times the rated continuous shaft power output. A dramatic example is the winch in a helicopter used to rescue people. It is not rated for that load, but it can do it once or twice in a row to quickly lift a person out of danger, then it needs to cool off while the next chopper lifts a couple. It can lift four out but then it starts to burn up.

 

I mean how do you calculate maximum possible power output in watts, based on current and voltage?

A motor does not output power, it consumes power. Why do you seem to be confused on this point?

 

Which form of power??? Torque times speed??? or something else???

 

A motor can be operated above full load current. 10 amps is less than the stall current, which is 11.8 amps. I know if you operate it above full load current, it'll overheat and possibly damage the motor, but i am trying to calculate maximum possible power output.

You don't have enough information.

The output power of the motor is torque multiplied by rotational speed. You don't have either of those numbers, both of which depend on a variety of factors.

Plus, the notion of "maximum possible power output" is very ill-defined. Max output for how long? One hour? One minute? One second? One millisecond? Almost certainly very different answers in each case. Plus, what is the criteria you are using to determine what constitutes the maximum? The max at which it can run continuously? The max at which it can run for one minute without sustaining damage? The max it can run at before it is destroyed?

I couldn't find that part number of Mabuchi's website. The closest I could find was RS-555PJ-3255

https://product.mabuchi-motor.com/detail.html?id=224

I didn't see any legend for their naming conventions, so I don't know what the difference might be. Perhaps there's something if you register and login -- I'm not willing to do that.

For the motor I found, the most efficient operating point outputs 7.92 W at an input power of 11.1 W, for a max efficiency of about 71%. If you operate it away from that point, you can expect the efficiency to go down, probably by a considerable amount as you try to push it to its limits.

 

The specific expression of a motor shaft power output is expressed by input voltage times input current times the motor efficiency, and the efficiency varies with the operating conditions, such as the load and the temperature. and the voltage supplied.
THAT is why there are CURVES published describing motor performance.
The"locked Rotor" current describes the instant starting current, that is why it is often provided.

 

Sorry, I am not sure about this question. Mabuchi 555 is a motor. It is supposed to give you speed output in RPM. Not the power output in watts. https://www.asapwire.com/ProductDetails.asp?ProductCode=RS-555PH-3255

 

I did not pose any question in post #12.

 

@Man10 :

Are you talking about mechanical power when used as a motor or electric power when used as a generator?

 

I mean how do you calculate maximum possible power output in watts, based on current and voltage?

I believe you already have the answer, the full-load current times the voltage. Of course it depends on how the manufacturer defines "full-load" but if it was me, I'd pick the point where the output is maximized. If you load the motor to where it is drawing more than the full-load current, the rpm will drop and you'll actually get less shaft work out of it. Like shifting your car into too high a gear while under load. Lots of load on the engine, but not enough rpm.

If you need more power for limited time periods, use a hefty flywheel. That angular momentum gives you "braking horsepower" far in excess of the steady state power.

 

Motor power electrically is calculated as V x I. But remember a motor has internal resistance and back emf. So in fact the V is really the back emf of the motor.
At stall the back emf is zero. So at stall the motor consumes zero watts. All the power delivery the power supply goes into heating the internal resistance.
You can also look at this mechanically. Power out of the motor is rotational speed times torque. I the case given you don't need to know the torque. And speed is zero. So the motor shift power at stall is zero watts.
Remember that power is a measure of the work done. No movement , either rotational or linear means no work is being done.

 

So in fact the V is really the back emf of the motor.
…
At stall the back emf is zero. So at stall the motor consumes zero watts

Tell that to the battery, it doesn’t seem to know that. When I stall my motor, the battery runs down faster!

You are conflating the electrical power input and the mechanical power output.

 

Kaindub has it backward! The back-emf is what limits the current. So at a stall the current is mostly limited by the resistance, and so the power consumed rises and is all converted to heat. So the motor will burn up in a fairly short time.