How to Troubleshoot Inaccurate Voltage Measurement with a Multimeter
A multimeter is a commonly used circuit measurement tool that can measure parameters such as current, voltage, and resistance. When using a multimeter to measure voltage, it is necessary to select the appropriate range gear based on the magnitude of the voltage being measured to ensure accurate measurement.
On a multimeter, there are usually multiple voltage range settings to choose from, such as 2V, 20V, 200V, 600V, etc. Each setting indicates the upper limit of the measured voltage. For example, if we want to measure a voltage of 5V, we should choose the 20V setting, not the 2V setting, because the 2V setting cannot display the accurate value of a 5V voltage.
If the measured voltage exceeds the selected range gear, the multimeter will not display accurately. Therefore, before measuring, an appropriate gear should be selected based on the estimated range of the measured voltage.
Reasons for inaccurate voltage measurement with a multimeter and repair methods
There may be various reasons why a multimeter may not measure voltage accurately. Below are some common causes and their corresponding remedies:
Low battery: If the multimeter battery is low, it may lead to inaccurate measurement results. The solution is to replace the battery with a new one and ensure that the battery polarity is correctly installed.
Poor contact: Poor contact between the voltage measurement lead of the multimeter and the circuit being measured can also lead to inaccurate measurement results. Check the leads' plugs and connectors for cleanliness, corrosion, or oxidation. If present, clean or replace them.
High internal resistance: The internal resistance of the multimeter itself may also affect the accuracy of voltage measurement. Before measuring voltage, you can short-circuit the two leads and read the short-circuit current to determine whether the internal resistance is too high. If it is, the multimeter needs to be repaired or replaced.
Temperature influence: Temperature variations in the measuring components of a multimeter may lead to inaccurate measurements. When conducting precise voltage measurements, one may consider utilizing temperature compensation features, or alternatively, stabilizing the temperature within a laboratory environment prior to measurement.
Misoperation: Improper operation may also lead to inaccurate measurement results. Before measuring, it is necessary to read the instruction manual of the multimeter and select the appropriate range gear according to the voltage range to be measured.
