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Mini clamp useful for battery charger testing

4.0

This mini clamp features a DC milliamp mode which I found very useful when qualifying a charger for a Lithium battery application. With these LiIon charger ICs the terminal voltage is monitored, so when trying to measure the charger current with a traditional mA meter (in-line), the voltage offset introduced by the Ammeter was enough to cause the charger IC to shut down. I ordered the mini-clamp and it provided a great means of measuring the current without disturbing the circuit.

Note: Since it is measuring small DC currents it is very sensitive to the magnetic fields in the vicinity of the measurement wire. For accuracy it is best to hold the meter adjacent to the wire, zero it, then clamp around the wire. Also of note, fast, high current transients will magnetize the clamp slightly, so the measurement will pick up an offset after the current spike, which persists even after the unit is unclamped. I called about this and they said this is normal for it to become slightly magnetized - just re-zero the unit and keep going - which I did. So for best DC current measurement results, try to measure currents that are not fast changing.

All that being said, it is a very handy unit for any DC current application, down to the mA range, and of course it works for AC as well, for any number of household applications. I have used it for chargers, Triac power circuit evaluation, car/RV charger troubleshooting, and for digital current loop evaluation.

Brian on Apr 17, 2015 I found this helpful (1)