HX711 and 50kg load cells - unstable values

Hi there

I have a problem with unstable values from 4 (50 kg)- load cells. The load cells are connected like shown here - with a HX711 ADC: Load Cell Amplifier HX711 Breakout Hookup Guide - learn.sparkfun.com

Load cells : Load Sensor - 50kg (Generic) - SEN-10245 - SparkFun Electronics

I have used the code shown in the link - where I have to find the "calibration_factor" first. There is no problem in finding this - it was about -3050, which means, that when I add 61,9 kg on the load cells - the value show 61,9 kg.

There are 2 problems:

  1. When I take of the load of 61,9kg and add it again - I do get another value - not the same - ex 58 kg.
  2. The value of 61,9kg decreases over time - ex it starts with 61,9kg and decreases to 60 in 15 minutes, and goes on for a long time.

I have tried a lot, and cant find a solution for this problem. I really hope there is some help out there.

Thanks
Gorm

The combinator board has a connector for a temperature sensor. Do you have the temperature changes in your calculation? How stable is your power supply?

How are the load cells arranged mechanically?

Hi there

First - thanks for reply. I found the solution. Until now I connected the load cells black wire to white wire - like on sparkfuns instruction page Load Cell Amplifier HX711 Breakout Hookup Guide - learn.sparkfun.com

But the solution is to connect them like on this page - black to black and white to white... load cell - Arduino with Weighing Scale - Electrical Engineering Stack Exchange

Gorm