The Myth of Extended Range

A customer recently asked us how our load cells compared to other manufacturers that promote “extended range load cells”. These extended range load cells utilize a 10V excitation with the claim that by using a higher excitation you get a more sensitive tension signal. For reference, Montalvo’s load cells utilize a 5V excitation.

So the idea is that for a 100 lb load cell with a 5V excitation, you would get 125 mV of output, whereas with an “extended range” load cell you would get 250 mV of output due to the 10V excitation. The sales pitch is that with double the input, you get double the output and thus have a more sensitive load cell for detecting any changes in tension.

Unfortunately the reality is that this does not affect the sensitivity of the load cell.

Mathematically, sensitivity is equal to Change in Input divided by Total Output (S=CI/TO)

So in our two examples:

Example A:  125 mV / 5 V = 25 (mV/V)

Example B: 250 mV / 10 V = 25 (mV/V)

Increasing the excitation voltage doesn’t change the end result at all. Also note that this value is independent of the amplifier used, so even using a more sensitive amplifier will not have an impact on this.

When choosing the best load cell for your application focus on quality, true performance, and the support you will receive, and don’t be fooled by the myth of “extended range”.