How to Find the Static Sensitivity of Load Cells: A Practical Step-by-Step Guide
Published on August 26th, 2025 at 08:56 am
In industrial weighing, automated production, and similar scenarios, the static sensitivity of a load cell directly determines the accuracy of weight measurement. It represents the load cell’s ability to respond to changes in input weight with output signals under “slow loading or steady-state weight” conditions, typically expressed in units of “mV/V (millivolts per volt)”. Whether for selection and procurement, on-site operation and maintenance, or calibration and verification, accurately obtaining static sensitivity is a crucial step. This article will help you quickly find the static sensitivity of load cells through 4 practical methods while avoiding common misunderstandings.
I. First: Why Does Static Sensitivity Matter?
The core of static sensitivity lies in the ratio of “change in input weight” to “change in output signal” (Formula: S = ΔOutput Voltage / ΔInput Weight / Excitation Voltage). Simply put, if a load cell is labeled “2.0mV/V”, it means that when 1V of excitation voltage is applied to the cell, the output voltage will increase by 2mV for every 1kg increase in weight.
Its importance is reflected in three aspects:
- Matching for Selection: For example, a food packaging line requires a sensitivity of 1.5-2.0mV/V (balancing accuracy and anti-interference), while aerospace testing may need high sensitivity of 0.5-1.0mV/V;
- Accuracy Assurance: Excessive deviation in sensitivity can lead to inaccurate weighing data (e.g., displaying 98kg instead of the intended 100kg);
- Operation, Maintenance, and Calibration: Regular verification of sensitivity helps detect issues such as load cell aging and malfunctions in a timely manner, preventing production accidents.
II. 4 Methods to Quickly Find Static Sensitivity
Method 1: Check the Product Datasheet (Most Direct, Suitable for Selection/Procurement)
This is the most convenient way to obtain static sensitivity. Especially when you haven’t accessed the physical product, you can accurately locate the parameter through the datasheet (technical specification sheet).
- Where to Find the Datasheet:
① Official websites of sensor brands （eg: MicroTess）
② Quotations or supporting materials provided by suppliers (you can proactively request them during procurement);
③ Appendix pages of product packaging boxes/instructions.
- How to Locate the Parameter:
After opening the datasheet, directly navigate to the “Electrical Specifications” or “Sensitivity” section. It is usually labeled as “Static Sensitivity” or “Rated Sensitivity” in a format like “2.0±0.02 mV/V” (±0.02 indicates the error range).
- Notes:
Some datasheets distinguish between “Rated Sensitivity” and “Actual Test Sensitivity”. For selection purposes, refer to “Rated Sensitivity”; for calibration, refer to “Actual Test Sensitivity”.
Method 2: Check the Load Cell’s Physical Markings (Quick On-Site Check, Suitable for Operation & Maintenance)
If you need to confirm the sensitivity urgently on the workshop site without a datasheet, you can directly check the load cell’s physical markings—manufacturers print core parameters in prominent positions.
- Locations of Markings:
① Metal nameplate on the sensor housing (commonly found on the top or side of load cells);
② Label inside the junction box (some small sensors have parameters attached inside the junction box);
③ Identification card on the cable (a few flexible sensors have parameters printed on the cable).
- Common Label Formats:
Simplified labels include “SENS: 2.0mV/V”, “Static Sensitivity: 1.5mV/V”, and some Japanese-made sensors are labeled as “Sensitivity: 2.0mV/V”.
- Notes:
For older load cells, markings may become blurred due to wear. In such cases, record the sensor model (e.g., “LC100-500kg”) and contact the manufacturer’s customer service to inquire about the corresponding parameters.
Method 3: Experimental Measurement (Accurate Verification, Suitable for Calibration/Testing)
If you need to confirm whether the actual sensitivity of the load cell meets standards (e.g., suspecting inaccurate data or after sensor maintenance), you can obtain the real value through experimental measurement—a method most commonly used by technicians.
- Required Tools:
Standard weights (accuracy class ≥ Class M1, weight recommended to be 20%-50% of the load cell’s full scale, e.g., 100kg weights for a 500kg load cell), DC regulated power supply (output voltage matching the load cell’s rated excitation voltage, e.g., 10V DC), high-precision multimeter (resolution ≥ 0.1mV, such as FLUKE 17B+) or signal amplifier.
- Step-by-Step Operation Process:Preparation: Fix the load cell on a horizontal test bench, connect the regulated power supply (ensure voltage stability with an error ≤ ±0.1V), and connect the multimeter to the sensor’s signal output terminal (clearly distinguish between positive and negative poles);
- Measure No-Load Output: Without applying any weight, wait for the multimeter reading to stabilize, then record the no-load output voltage V0 (usually a few millivolts, e.g., 0.5mV);
- Measure Loaded Output: Slowly place standard weights W (e.g., 100kg) to avoid impacting the load cell. Wait for the reading to stabilize, then record the loaded output voltage V1 (e.g., 4.5mV);
- Calculate Sensitivity: Substitute into the formula S = (V1 – V0) / W / Excitation Voltage, with the unit being mV/V.
Example: If the excitation voltage is 10V, V0 = 0.5mV, V1 = 4.5mV, and W = 100kg:
Initially, an incorrect calculation might yield S = (4.5-0.5)/100 /10 = 0.04/10 = 0.004 V/V = 4.0 mV/V. However, the correct logic is: Sensitivity represents “output mV per kg of weight per V of excitation”. The output change corresponding to 100kg weight is (4.5-0.5) mV = 4mV. For a load cell with a full scale of 500kg, 100kg is 1/5 of the full scale, so the full-scale output change is 4mV × 5 = 20mV. Thus, the sensitivity S = 20mV / 10V = 2.0mV/V (this is correct; the previous step omitted “full-scale conversion”, which is corrected here);
- Optimize Accuracy: Repeat the measurement 3 times and take the average value (interval of 1 minute between each measurement to avoid the impact of sensor heating). Meanwhile, control the ambient temperature at 20±5℃ (sensitivity may drift by 0.1%-0.3% for every 10℃ temperature change).
Method 4: Read via Weighing Indicator/Software (Intelligent Scenarios, Suitable for Automated Production)
Most modern industrial weighing systems are now connected to intelligent indicators, PLCs (Programmable Logic Controllers), or IoT platforms. Static sensitivity can be directly read or calculated on the equipment without manual measurement.
- Applicable Scenarios:
Weighing modules in production lines, intelligent truck scales, automated sorting equipment (e.g., load cells in assembly lines of auto parts factories).
- Operation Steps (Taking Weighing Indicator as Example):
- Turn on the indicator power, enter the “Parameter Setting” mode (usually by pressing the “Menu” or “Setting” key and entering a password, such as “1234”);
- Locate the “Sensor Param (Sensor Parameters)” or “Calibration” menu, then select “Sensitivity Read” or “Auto Cal (Auto Calibration)”;
- If “Sensitivity Read” is selected, the indicator will directly display the current static sensitivity of the load cell (e.g., “2.0mV/V”); if “Auto Cal” is selected, follow the prompts to place standard weights, and the indicator will automatically calculate and save the sensitivity value.
- Supplementary Operation for PLC/Software:
If connected to a PLC (e.g., Siemens S7-1200), the sensor’s output signal can be read through programming, and sensitivity parameters can be viewed on the “Equipment Monitoring” page of the HMI (Human-Machine Interface). If using weighing software (e.g., LabVIEW), a “Sensitivity Calibration” wizard can be set up in the “Data Acquisition” module to automatically generate a sensitivity report.
III. 3 Common Misunderstandings to Avoid
- Confusing “Static Sensitivity” with “Dynamic Sensitivity”:
Static sensitivity is for “slowly loaded steady-state weights” (e.g., warehouse weighing), while dynamic sensitivity is for “rapidly changing weights” (e.g., dynamic sorting in assembly lines). They cannot be used interchangeably—for instance, using a sensor with high dynamic sensitivity to measure static weight may make it more susceptible to vibration interference.
- Overpursuing High Sensitivity:
Higher sensitivity is not always better! A high-sensitivity sensor (e.g., 0.5mV/V) is more responsive to small weight changes but is also more vulnerable to temperature and electromagnetic interference, making it suitable for precision testing scenarios. For ton-level industrial truck scales, a sensitivity of 1.5-2.0mV/V is sufficient, as it balances accuracy and resistance to workshop interference.
- Ignoring the Error Range:
The “±0.02mV/V” in sensitivity labeling represents the allowable error. As long as the actual measured value falls within this range, the sensor is qualified—there is no need to pursue a value “exactly equal to the rated value”, as this would increase unnecessary calibration costs.
IV. Summary: Choose the Right Method for Different Scenarios
- Selection and Procurement: Prioritize “Method 1 (Check Datasheet)” to quickly match requirements;
- On-Site Operation and Maintenance: Use “Method 2 (Check Markings)” for efficient confirmation in urgent situations;
- Calibration and Testing: Adopt “Method 3 (Experimental Measurement)” to obtain accurate real sensitivity;
- Automated Production: Utilize “Method 4 (Read via Indicator/Software)” to adapt to intelligent systems.
If you are still unsure about how to select a load cell with appropriate sensitivity or need a customized calibration solution, please contact our technical engineers directly. Provide your application scenario (e.g., “food packaging line, full scale 100kg”), and we will recommend matching products and parameters for free.
