09/10/2025 5:21 am
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I’m measuring the current draw of a low-voltage load and noticed my handheld DMM, in mA mode, is dropping about 0.6 V across itself. Is that normal “burden voltage,” and what’s the best way to reduce it?
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21/10/2025 6:16 am
Yes, the 0.6 V drop you’re seeing is the meter’s burden voltage, which is the voltage lost across the DMM when it measures current. In mA mode, the meter places a small internal shunt resistor (and often a fuse or protection components) in series with your circuit to sense current, and this resistance causes a voltage drop equal to V=I×Rmeter.
For example, a 0.6 V drop at 60 mA means the meter adds about 10 Ω in series, which can significantly affect low-voltage circuits by reducing the actual voltage reaching your load.
To minimize this, you can use an external low-value shunt resistor and measure the voltage across it with the DMM in voltage mode, then calculate current using I=V/RI = V/R.
Alternatively, use a dedicated low-burden current sense amplifier or sensor such as the INA219, a DC clamp probe that measures current without inserting resistance, or the meter’s 10 A input (which usually has much lower internal resistance) if the current is within safe limits.
These methods help keep the measurement accurate without disturbing the circuit’s operating voltage.
