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I'm given these ratings /spec for load cell / sensor:

  • Range: 0-200kg
  • Output sensitivity: 0.7 ± 0.15mV / V
  • Nonlinear: 0.05% F.S
  • Hysteresis: 0.05% F.S
  • Repeatability: 0.05% F.S
  • Creep: 0.05% F.S/3min
  • Zero output: ±0.1mV/V
  • Input impedance: 1050±10Ω/1050±10Ω (self-compensation) Output impedance: 1050 ± 10Ω
  • Operating temperature: -10~+45°C
  • Wiring method: red (power positive), black (power negative), green (signal positive), white (signal negative)
  • Zero temperature drift: 0.05% F.S/10°C
  • Temperature sensitivity drift: 0.05% F.S/10°C
  • Insulation resistance: ≥2000MΩ
  • Excitation voltage: 3~10VDC
  • Overload capability: 150% F.S
  • Four-corner error: ±0.05% F.S

I know this is likely dumb question, but is the sensitivity there 0.7V +/- 0.15mV, or is this 0.7mV +/- ..? Probably 700mV/V is too much, but 0.7mV/V sounds too little .. ? (or does it..)

If 0.7mV/V, if I'm applying 5V input - that's my plan - this will be output range 0 - 3.5mV, which seems too low ?

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  • \$\begingroup\$ From the information that you provide, the only conclusive answer that can be given is that; The output sensitivity is 0.7 [NO UNIT] +- (0.15 mV/V).. So the output sensitivity here has no unit, but it varies with 0.15mV pr. V, That seems strange. I would bet that there is some more information in the datasheet which when put together with this makes everything make sense. I think that the output sensitivity is relative to the supply voltage, so you probably can't just equate 0.7 to 700mV or 0.7mV, it probably depends on your supply voltage. \$\endgroup\$
    – Vinzent
    Sep 21 '19 at 7:10
  • \$\begingroup\$ Hey @Vinzent, don't have datasheet but supplier (seller) just has description as i c&p above. The item is as here : link \$\endgroup\$
    – v01d
    Sep 21 '19 at 7:20
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I think that what they mean by "Output Sensitivity" is what is also sometimes referred to as the "Full-Scale Deflection", and the reason that they are not giving it a unit is because it is relative to the supply voltage, or here "Excitation Voltage", which they require to be between 3V and 10V.

So in other words, this is how I would calculate the parameters I need to use this sensor;

First we choose a supply voltage between 3V and 10V, lets use 3V for this example.

Vcc = 3v

Now we calculate the Full-Scale Deflection voltage, ie. the voltage out of the sensor when the sensor is under full load.

Vfsd = Vcc * 0.7 = 2.1V

Now we look at the range of the sensor which is 0-200kg, from this I would assume that Vfsd corrosponds to 200kg of load on the sensor, so to calculate the output voltage (Vo) pr. kg of load on the sensor we simply divide;

Vo = Vfsd / 200kg = 2.1V / 200kg = 10.5 mV/kg

To this we have to add an error of +- 0.15 mV/V, so at the full scale deflection the error will be;

Vfsd * 0.15mV/V = 2.1V * 0.15mV/V = 0.315mV

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  • \$\begingroup\$ Oh i see. So if I want to use 5V, then that's Vfsd = 3.5V, or Vo = 17.5mV/kg. \$\endgroup\$
    – v01d
    Sep 21 '19 at 7:50
  • \$\begingroup\$ Btw, about Output Sensitivity. This is how Sensitivity explained in relation to load cell (for weighting scale) : "The sensitivity of a load cell is defined as full load output voltage in relation to the excitation voltage. It is generally expressed in mV/V. This value corresponds to the voltage deviation caused by the load cell at full load when excited by a 1V source. The sensitivity of load cells is very low (generally about 2mV/V). If a system has a 3.3V excitation voltage then at full load, the output voltage will be 6.6mV" (source: EE times, weighting scale design) \$\endgroup\$
    – v01d
    Sep 21 '19 at 7:53
  • \$\begingroup\$ sorry but I looked more at how they generally specify these load cells, and I think, apologies for this, your interpretation is not / shouldn't be right. See here for example : link. Thus I think it should be 0.7mV/V +/- error for my bar. \$\endgroup\$
    – v01d
    Sep 22 '19 at 18:07

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