RS-555SH Motor

[vidarr]

I have a RS-555SH Motor and downloaded the datasheet for it and see it comes in a number of voltages. The one I have is either 12V or 24V. How can I know which voltage it is?

Besides the one page datasheet, this is what I know:
It runs on 5V slow and weak and obviously not the right voltage.
12V decent speed and power.
24V fast and powerful.

This is going to be used for a fan, so the more power the better.

Thank You!

[Benta]

Spin the motor at a known RPM, eg, with an electric hand drill, and measure the voltage at the terminals.
Both types have an rpm of ~6400 at nominal voltage (12 or 24 V).

Example: If your hand drill has an RPM of 1500, the generated voltage will be either 1500/6400 x 12 V (~2.8 V) or 1500/6400 x 24 V (~5.6 V).

[vidarr]

Brilliant! I have something that measures rpms. I can use a ESP32 to adjust (using PWM) the rpms.

This makes so much sense that I failed to see it.

Thanks so much!

[Benta]

I didn't mean drive the motor electrically I meant spin it mechanically with another motor, eg, power drill.

[vidarr]

Yeah, I understood that. I have another motor I am going to hook to the  RS-555SH Motor to drive it.

Thanks!

[vidarr]

The result was this:

1800/6400 x 12 V = 3.375

1800/6400 x 24 V = 6.75

This seemed easier when I first thought about it. How exactly does this tell me if it is a 12v or 24v motor?

Thank You!

[Benta]

Is the voltage what you measured on the motor terminals?

[vidarr]

Yes.

edit: BTW, my drill is almost exactly 1800. I hooked the drill to the motor and put my DMM to the terminals and then pulled the trigger. I did it a few times just to be sure. The voltages are solid, for sure numbers.

Thank You!

[Benta]

Yes.

edit: BTW, my drill is almost exactly 1800. I hooked the drill to the motor and put my DMM to the terminals and then pulled the trigger. I did it a few times just to be sure. The voltages are solid, for sure numbers.

Thank You!

That can't be. If you spin the motor at 1800 rpm, you'll either get ~3.8 V for a 12 V motor or ~6.8 V for a 24 V motor. You can't get both.
What you've posted is the calculation, not the measurement.

[Kleinstein]

The DC motors run over quite some speed range. There is not a really fixed voltage, but one has to find your suitable compromise of power and expected life. Lets say you get the 12 V model. Than some 8 V may be good for a relativeyl long life use (e.g. FAN) and maybe 18 V OK for short time use where the life time is not impoartant and maybe 30 V for very short use with enough loading so it would not run too fast.

So likely the motor is a 24 V type. Normally half the rated votlage is already not so bad.

[vidarr]

The only variable that is different in your equation is the RPMs of the drill "1800".

https://www.milwaukeetool.com/Products/Power-Tools/Drilling/Drill-Drivers/2606-20

So, I plugged that into your equation for both 12v and 24v to see the results: 

1800/6400 x 12 V = 3.375

1800/6400 x 24 V = 6.75

Maybe the RPMs are not 1800 anymore? The drill is a few years old, but in good condition.

[vidarr]

"So likely the motor is a 24 V type. Normally half the rated votlage is already not so bad."

Yeah, I just don't know the rated voltage. I have a 19v power supply, so I think I am going to go with that. But, I still want to understand that equation and how it works.

Thanks Guys!