Arduino + HX711 + 100kg load cell works up to 50kg then goes wild

Hello,

I have been using an Arduino, Wheatstone amplifier shield, 100kg S load cell and Labview for monitoring a sinusoidal compressive loading situation. I had electrical issues with this setup because I had to wire a variable resistor to the Wheatstone amp so that I could get a signal at higher loads. The wiring was tedious and fragile and I had to repair it several times until the solder pads on the shield were toast.

I then went to try another method where I simply hooked the 100kg S load cell to the Arduino via the HX711 board. This works well up to about 50kg but after that things start spiking, drifting and when the load is high enough (> 60kg) the plotter flat lines.

I have attached an image of my setup and a sketch of the wiring diagram.

C:\Users\Kevin Lytwyn\OneDrive - McMaster University\Pictures\Capture.MHT

From doing a bit of reading perhaps the cheap (green/Chinese) HX711 board I have is not good enough… if so I think I will go for the SparkFun Qwiic Scale. Another idea I had was maybe the load sensor is toast as it has been used for about 1.5 years now and not under ideal conditions. The last thought I had was going back to the original setup with the Wheatstone shield but I didn’t like how fragile that setup was.

Does anyone have any tips?

Thanks in advance!