weskel

I posted this in the Futaba forum but should have been posted here.

Wondering what the AMP draw is on a standard ball bearing servo while in motion under a load running with a 6 volt receiver battery.

Thanks

guver

My Feedback: (325)

It can vary of course and depends on the actual load. We could stall one and get the max perhaps.

BuschBarber

My Feedback: (2)

If you have a Wattmeter or an H9 Current Meter, you can easily measure the current draw and voltage, of any servo, or your entire system, under load. You would stall one or all of your servos and record the measurements.

Zor

Hello weskel,

Ball bearing or sleeve bearings would not affect the current intensity worth talking about.

I assume that by "in motion" you mean while rotating.

The curent intensity would vary with the load which is not specified in your question.
The current would also varyduring the rotation as a factor of how far it is from its commanded angle.

A proper answer to your question would require a current sensor, a torque sensor, a rotation angle sensor and a fast dual graphic printer.one needle for current and one for torque on the Y axis . The x axis driven by the rotation angle sensor.

The only valuable current reading easily available is when the servo is immobilized (jammed) and we then measure the current as pointed out already.

Zor

hellcat 1

I wrote a letter to RC Reports radio colum about 3 years ago showing the current draw on a retract servo. I made a device out of a plastic box, a servo extension, and jacks to plug a meter into to test the current draw of a system or servo. A standard servo will easily draw 500 ma when stalled. A retract servo more than that and that can destroy the motor drive transistors in short order. I test all my sytems with it to make sure none of my servos are stalled or dragging. You would be surprised how many setups put excessive strain on the servos and the battery. Sam

rmh

I have to disagree on this one -
The simple test is as Busch Barber noted - and the meters we have available for basic modeller use are just fine. So a inline meter between battery and rx will tell you all you need to know
And actually tell you info you likely did not anticipate -such as sticky ball joints in linkage or bottoming out on throw or linkage interferrence etc.. well worth knowing as these loads are among the worst - they are not from airloads - they simply ad to the airloads and can quickly sap the batteries .
When I setup a model for a customer (we use all JR/Spektrum) a recorder is inserted between batt and rx an I simply watch th meter as I run each function.
You as ked "how much is being drawn in motion
I simply can't tell you - you must establish what the draw is when NOT under load then make full travel on each servo and read the meter and watch for unusual changes.

Zor

Hi rmh,

You start writing "I have to disagree on this one"but in realityyou and Iare not in disagreement.

I have to assume that your recorder is recording and printing the current intensity. The current waveform you would get would vary with the speed at which you are moving the transmitter stick Moving the stick slowly would record a low intensity that last about the time taken to move the stick. A fast move of the stick would record a higher intensity that last a short time.

In either case there is no indication of the angle of the control surface position in relation to the current draw. The speed of the stick motion would hardly be linear if handle by hand and be different evry time the stick is handled.

Post #1 read ___
Wondering what the AMP draw is on a standard ball bearing servo while in motion under a load running with a 6 volt receiver battery.

I had to make guesses as to his meaning ___
I interpreted "under a load" as measning possibly under actual flight condition and the load being due to the airstream pass the surface and all its variables.
Then "while in motion under a load" I assumed that the "while in motion" meant the rotation of the servo / control surface.

Ialso assumed he was looking for "how the current intensity is (was) varying during the rotation under a load that he did not specify. Was the load supposed to be an airstream of differnt velocities ? Was it suppose to be a steady constant opposition to the rotation provided in some way ?

So I posted on the basis that a recorder would draw (print) the currnt intensity versus angle of rotation and we would then be able to create any imaginable load desired.

I agree that what you described is about all we need to know and that is exactly the type of experiment I played with when I posted results including pictures of the meter readings.

I also considered that "what we need to know" may be different than "what one might want to know".
I just was not sure what was really wanted. I still am not sure.

I do not think any harm has been created and I hope the readers are now understanding.

Best regards de Zor.

rmh

Yes , speed which introduces DIFFERENCE in pot position is going to showmore load.
What I should have clarified is that I look at a slow movement , to find mechanical interferrences to servo movement
Once these are eliminated, then a reading of actual servo loadings can be done.