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.
