Harvest - Load Cell Testing

Visual Inspection / Wire Wiggling

1. Check all the wires coming down from the Libra Cart box for any signs of visual damage (cuts, tears, pinches, rodent damage, etc.). Trace from the Libra, to the junction box, to each load cell.
2. While going over the cables visually, wiggle, bend, or shake all cables one at a time.
3. Keep an eye on the display while moving the cables.
4. The incoming signal should not change when a wire is wiggled. If the weight spikes when a cable is wiggled or bent, the wiring in the cable is likely compromised.

Consistency Check

1. Hang off or stand in all four corners/sides of the cart and note the behaviour of the weight display while hanging off each side. All sides should display similar weights, in the same polarity, when tested.
2. If a corner/side does not match the others or read correctly, direct investigation towards load cells on that region of the cart.

Hammer Test

1. Use a rubber mallet, or similar soft but sturdy tool, to tap the frame around each load cell. Never hit the load cell directly as that can damage it.
2. While tapping the frame note what the weight display does. A properly functioning load cell will increase the weight reading when tapped then decrease back to the starting reading after a few moments. All load cells should increase to a similar weight reading and return to the same starting reading.
3. If one of the load cells does not match the others when similar force is applied, direct investigation towards that cell.

Ohm / Resistance Test

1. Use a multimeter set to the Ω (Ohm) setting (or an Ohm meter) to measure the resistance between all of a load cell’s leads. A four pin cable should result in six readings (this quantity will increase as the number of cable leads increase).
2. You should be able to pair off each reading with another from the same cell. If two or more of the numbers can't be paired off, that indicates a potential problem.
3. Repeat for all load cells.