1. Definition: What is the excitation voltage?

Load cell requires excitation voltage to generate output signal. This is directly related to the basic working principle of the inner Wheatstone bridge. The excitation value of the load cell is generally listed as the "recommended" and "maximum" excitation voltage by the manufacturer. As the name suggests, the recommended value is the value recommended by the manufacturer for the best output results, and the maximum value is the value that should not be exceeded.

2. Is the excitation voltage of the load cell important?

As mentioned earlier, the load cell requires an excitation voltage to produce an output signal. When a load is applied to the battery, a higher excitation voltage will produce a higher output voltage swing.

In a way, the bigger the signal, the easier it is to measure and digitize. However, high excitation voltage also has disadvantages. A higher voltage through the resistance strain gauge (including Wheatstone bridge) will cause more current to flow and heat the strain gauge. The battery body acts as a heat sink to keep the meter cool. If the maximum rated excitation voltage is exceeded, heating will cause signal disturbance or meter failure. Also, in battery-powered devices, a high excitation voltage (and therefore current) will cause the battery to drain much faster than a lower excitation voltage through the circuit.

For a given load cell, an excitation voltage below the maximum specified by the manufacturer is acceptable. The manufacturer's recommended value is clearly the best, but does no harm at lower excitation voltages. For example, 5V is a very common excitation voltage for modern load cells. Modern instrumentation amplifiers are much better than older designs and their output signals are not affected by lower excitation voltages. It is perfectly possible to use a 5V excitation amplifier with a recommended 10V excitation load cell. (The reverse is not true!)

Finally, when selecting the excitation voltage, consider the common-mode voltage generated by the battery output. An amplifier or other signal conditioning electronics must be able to handle this common-mode voltage, which has a value of 50% of the excitation voltage. For example, a 10V excitation produces a 5V common-mode voltage. Typically, these amplifiers provide the excitation voltage to the battery; In this case, the use of an external excitation voltage is not recommended.