Connecting multiple full-bridge load cells together with HX711

Question

I am doing a project where I need to connect 2 or 3 full-bridge load cells (the one with 4 wires) together. I am using this type of load cell:

I have read that to have such an arrangement I need to connect the load cells in parallel and connect them to an HX711 and then connect it to the Arduino board to get the readings.

I have done the same thing and calibrated the combined load cells to get a calibration factor. Now my problem is when I am putting the load on the platform there is a considerable change in the readings when the location of load is changed on the same platform. My doubts are:

1. Do I need to use individual HX711s for each of the load cells?
2. How do I calibrate the load cells when there are connected in parallel?

Answer 1

1. Do I need to use individual HX711 for each of the load cells?

YES

2. How do I calibrate the load cells when there are connected in parallel?

Each sensor must share exactly the same excitation with short, low-resistance wires then the result is the average of all outputs, or they may be separately calibrated. This applies to 2, 3, 4 or more sensors.