load cell drift under strain

Sensors Force & Weight
1

I’ve been using a 2kg load cell (TAL220B) with ads1256 for a while, it works pretty well but still some annoying problems so far. When we test load cell with a standard weight, like a 500 grams scale, the scale would drift about 1 gram after an hour, which is quite precise (temp and moisture are stable).

But what we’d like to test is vibration generated by an object (like a motor), and we found under this circumstance, the average weight decrease significantly (~2 to 3 grams) after few minutes compare to a static object, but the average weight should remain the same since the average should be the weight of the motor upon load cell.

So, compare to our observation in the first paragraph, we’re wondering if a loadcell would drift bigger when it’s consistently deformed?

Thanks for your help in advance!

2

Make sure your dead end mounting point is extremely rigid.

3

What you’re describing sounds like “creep.”

Creep is the change in load cell signal occurring with time while under constant load and with all environmental conditions and other variables also remaining constant. Load cells tend to creep meaning they will change their output slightly over time when a weight is left on the scale for long (30+ minutes) periods of time. To calibrate for something such as a bee hive that will be permanently left on a scale:

  • - Place everything on the scale that will be the zero state (the hive plus any static ballast)
  • - Leave the scale for 30+ minutes
  • - Tare the scale with these weights
  • - Place two calibration weights onto the scale
  • - Leave the scale for 30+ minutes
  • - Calibrate the scale to this combined weight
  • - Remove one of the calibration weights and verify scale output
    • More information about load cells and creep can be found [[here](https://scalemanufacturers.org/PDF/LoadCellApplicationTestGuidelineApril2010.pdf). This calibration method may need to be repeated every season with changing temperatures and humidity.](https://scalemanufacturers.org/PDF/LoadCellApplicationTestGuidelineApril2010.pdf)
    4

    brow:
    Make sure your dead end mounting point is extremely rigid.

    I’ve checked it few times, and also the force generated by motor is not too big, it might not be the problem, but thanks for your advise!

    5

    YellowDog:
    What you’re describing sounds like “creep.”

    Creep is the change in load cell signal occurring with time while under constant load and with all environmental conditions and other variables also remaining constant. Load cells tend to creep meaning they will change their output slightly over time when a weight is left on the scale for long (30+ minutes) periods of time. To calibrate for something such as a bee hive that will be permanently left on a scale:

  • - Place everything on the scale that will be the zero state (the hive plus any static ballast)
  • - Leave the scale for 30+ minutes
  • - Tare the scale with these weights
  • - Place two calibration weights onto the scale
  • - Leave the scale for 30+ minutes
  • - Calibrate the scale to this combined weight
  • - Remove one of the calibration weights and verify scale output
    • More information about load cells and creep can be found [[here](https://scalemanufacturers.org/PDF/LoadCellApplicationTestGuidelineApril2010.pdf). This calibration method may need to be repeated every season with changing temperatures and humidity. [/quote]

    I understand there would be creep while using load cell, but I’m wondering is that whether the creep would be more severer while it’s distorted compared to stable, and I do calibrate it with different weight for multiple times, but still thanks for your extra knowledge.](https://scalemanufacturers.org/PDF/LoadCellApplicationTestGuidelineApril2010.pdf)