Understanding mV/V (millivolts per volt) is important if you work with load cells. It essentially measures how sensitive a load cell is and how it responds, which plays a big role in ensuring accurate performance.
Whether you’re building industrial weighing systems, fine-tuning force measurement equipment or adding load cells to custom projects, knowing mV/V will make a big difference to your system’s accuracy and reliability.
In this article, we’ll break down what mV/V means for load cells, why it’s key to getting precise measurements, and where it really matters.
What mV/V Means for Your Load Cell’s Performance
mV/V stands for millivolts per volt, which measures how much a load cell “responds” when it’s working. It’s a standard way to define the sensitivity of the load cell.
Practical Example
When you apply a voltage (let’s say 10 volts) to a load cell, the cell produces an output in millivolts based on the force or weight it experiences. The mV/V rating tells you how much output you can expect for each volt you apply.
For example:
A load cell with 2 mV/V means if you apply 10 volts of excitation voltage, the max output will be 20 millivolts (2 mV for each of the 10 volts).
If you apply 5 volts excitation, the max output will be 10 millivolts.
Signal Strength
The mV/V value defines the sensitivity of the load cell. A higher mV/V means the load cell produces more signal relative to the input voltage:
- More signal: Reduces noise or interference and improves measurement accuracy.
- Less signal: Requires more amplification, introduces noise and reduces precision.
Measurement System Resolution
A higher mV/V means a better resolution of the load cell output, meaning the more sensitive the load cell, the more the output signal changes for small load variations. This makes it easier for indicators, amplifiers or data acquisition systems to detect and measure these changes accurately.
Why is mV/V Important for Load Cell Accuracy?
Here are the 7 main reasons:
1. Load Cell Sensitivity
The mV/V rating tells you how much electrical signal (output) you can expect from the load cell for a given input (excitation voltage). This sensitivity affects:
- Accuracy: A higher mV/V means the load cell can produce a larger signal, which helps in more accurate measurements.
- System Design: It helps engineers choose the right equipment, like amplifiers or indicators, to process the output signal without distortion or loss.
2. Scaling and Calibration
The mV/V rating ensures the load cell behaves the same across different excitation voltages. Calibration relies on this consistent relationship so the load cell can produce repeatable and reliable readings under different conditions.
The mV/V value is critical during calibration as it defines the relationship between the input (voltage) and the measured output (force or weight). For example:
- If your system knows the load cell is 2 mV/V and sees 10 mV output with 5 V excitation, it can calculate the weight or force being applied.
3. Electronics Compatibility
Different load cells have different mV/V ratings so you need to match them with devices that can read their output correctly:
- Amplifiers and Signal Conditioners: These devices need to boost the tiny millivolt signal into something usable (like volts) for your display or control system. Knowing the mv/v rating means you can set the amplification correctly.
Higher mV/V means the output signal is easier to digitize with high precision and less chance of rounding or digitization errors.
- Indicators: Your indicator or display must be compatible with the expected mV/V range to get accurate readings. Mismatched components will give errors like incorrect scaling or insufficient resolution.
4. Excitation Voltage Flexibility
The mV/V rating is independent of the actual excitation voltage applied. This means you can scale the system by adjusting the excitation voltage and still get proportional outputs. For example:
- A load cell rated at 2 mV/V will output 4 mV at 2 V excitation or 20 mV at 10 V excitation. This makes the load cell adaptable to different power conditions.
5. Signal-to-Noise Ratio (SNR)
A higher mV/V means a stronger output signal:
- High output signal to noise means minor environmental or electrical noise will have less effect on the reading accuracy.
- Low SNR (associated with low mV/V) means the output is more prone to noise and less accurate.
6. System Troubleshooting
If the output doesn’t match what you expect based on mV/V, it’s a quick indicator of:
- Wrong excitation voltage.
- Bad wiring or connections.
- Faulty load cell or signal conditioner.
7. Sensitivity vs. Range Trade-off
A higher mV/V generally means more accuracy but might limit the load cell’s range. Designers often balance sensitivity and capacity based on the application’s requirements:
- For high-capacity applications, lower mV/V is often acceptable if durability is more important than ultra-precise measurements.
The mV/V rating is more than a number; it’s the key to designing, calibrating and troubleshooting a load cell system. It ensures all components – from the load cell to the electronics – work together to give you accurate and reliable readings.
What is the Load Cell mV/V Calculation?
The mV/V calculation for a load cell is the output signal in millivolts based on its rated sensitivity, the applied load and the excitation voltage.
Here’s how to calculate it step by step:
Formula:
Output Signal (mV) = (Rated mV/V Sensitivity) × (Applied Load / Full Scale Load) × (Excitation Voltage)
What Each Term in the Formula Means:
- Rated mV/V Sensitivity: The load cell’s specification, e.g. 2 mV/V.
- Applied Load: The weight or force applied to the load cell.
- Full Scale Load (FSL): The load cell’s maximum capacity (e.g. 100 kg, 10,000 lbs).
- Excitation Voltage: The voltage applied to the load cell, usually 5V, 10V or another constant value.
Example Calculation:
- Sensitivity: 2 mV/V
- Full Scale Load (FSL): 1000 kg
- Excitation Voltage: 10 V
- Applied Load: 500 kg
Calculation Steps:
- Calculate Load Ratio: Load Ratio = Applied Load / Full Scale Load = 500 / 1000 = 0.5
- Multiply by mV/V Sensitivity: Output per Volt = (Rated mV/V Sensitivity) × (Load Ratio) = 2 × 0.5 = 1 mV per Volt
- Multiply by Excitation Voltage: Output Signal (mV) = (Output per Volt) × (Excitation Voltage) = 1 × 10 = 10 mV
Important Notes:
At full load the output will be the full mV/V rating multiplied by the excitation voltage. In this case, for 1000 kg and 10 V, the output would be 2 × 10 = 20 mV.
The calculation assumes a linear relationship between load and output which is true for most load cells.
Applications Where mV/V Plays An Important Role
1. OEM Applications
Original Equipment Manufacturers (OEMs) use load cells in custom equipment and systems:
- A consistent mV/V rating for easier integration into their systems.
- Compatibility with a range of controllers and amplifiers for high-precision applications.
2. Industrial Weighing Systems
In tank and hopper weighing applications, load cells with the right mV/V rating will:
- Give accurate weight measurements for inventory control or batching.
- Work with amplifiers and indicators for signal processing.
3. Force Measurement and Testing
In testing equipment for aerospace, automotive and construction industries, mV/V will:
- Give precise force measurement during material testing, fatigue testing or structural analysis.
- Allow calibration for comparing data across test conditions.
4. Vehicle Weighing
In truck scales or weigh-in-motion (WIM) systems:
- mV/V rating for static or dynamic loading.
- High sensitivity is important for axle weights or overload conditions, especially at variable speeds.
5. Agricultural Equipment
Load cells used in harvesters, seeders or feed measurement applications:
- Stable and predictable mV/V ratings for weight-based distribution.
- Robust signal output to counteract environmental challenges (e.g. vibration, moisture).
6. Portable Weighing Systems
For portable systems like axle scales or field use weighing solutions:
- mV/V rating determines how easily the system can produce a signal in off-site, low power environments.
- Compatibility with compact indicators or wireless signal processors depends on mV/V output.
7. High Temperature or Harsh Environments
In mining, oil and gas and construction industries:
- mV/V rating is the baseline for load cells to operate reliably under temperature and environmental stress.
- High sensitivity means less calibration required even in harsh environments.
8. Multi-Load Cell Systems
In platform scales or weighbridges applications, mV/V ratings must be the same across all load cells for:
- Same output signal for balanced weight distribution.
- Accurate total weight calculation when summing signals from multiple load cells.
9. Robotics, Automation and R&D
In robotic grippers or automated handling systems:
- Load cells with mV/V ratings measure forces or weights with precision.
- Signal-to-load relationship is predictable for integration with controllers to adjust the system.
- Replicability of experiments across different setups and environments.
mV/V is more than a technical spec—it’s the foundation of load cell design, calibration and application.
Defining the relationship between input voltage and output signal, ensures accuracy, compatibility and reliability across many industries and environments.
Explore More and Enhance Your Load Cell Expertise with Help From Massload
Whether you’re troubleshooting a system, designing for high precision or selecting equipment for harsh conditions, knowing mV/V lets you make informed decisions and get the best results.
If you liked this article, check out our other articles about load cell technology, calibration tips and real-world applications to learn more and improve your systems.
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