Phidgets Forums

Hi,
I am using load cells with a PhidgetBridge 4x USB usually with load cells 0-5kg. For a project a need a 0-500kg load cell but most of the weighings will happen between 0 - 2kg, only in very rare and extreme exceptions it can go up to 150kg or more. Is the precision of the 0-500 Kg load cell in this area of 0-2Kg comparable to the small 0-5kg load cells? Or are they less precise or have other differences? Any information appreciated.

Many thanks,
Cheister

To measure 2kg on a 500kg load cell, you are using 0.4% of its full scale range. This would be equivalent to trying to accurately measure weights up to 20g on a 5kg load cell.

Possible? Technically, but you're approaching the point where many other small effects could skew the results significantly relative to the weight being measured if you're not very careful. For example, looking at our article on temperature effects on load cells, you can see that a 5kg load cell could drift as much as 15g over a temperature change of 6°C.

https://www.phidgets.com/?view=articles ... Correction

While temperature effects can be compensated for by merely zeroing the scale before each use, there are other things to consider as well: from the same article, we can see a difference up to +/-1.5g if the weight is significantly off-center using the same load cells. You'd also need to do a fair bit of averaging to get a decent reading out from the measurement noise, which is on a similar scale.

To sum it up, I don't recommend using such a large load cell if the bulk of what you are measuring is so much smaller, unless absolutely necessary.

Many thanks for the information @jdecoux .

I currently zero the scale after each measuring session and average the last three measurements during each measuring session. I don't need 100% precision but check if the difference to the last measurement is in a certain range with a tolerance.
This works already with a 5kg Load cell and even the drift over time and temperature did not make a problem so far.

May be I give the 500Kg or the 100Kg load cell (as a compromise) a try.