Thread: New Product ESR / IR Meter fo Lipos
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Old Jul 03, 2011, 05:26 PM
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Melbourne, Australia
Joined Jul 2005
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Wayne is the expert on this but I think he is on hols so here is a quick answer.

Total "resistance" in an AC circuit is a combination of in phase and out of phase voltage/current interactions. It is called impedance and varies with frequency. ESR is commonly specified for capacitors and is the sum of in-phase AC resistance of the capacitor in an AC circuit. That is the "DC" component at a particular frequency. It includes resistance of the dielectric, plate material, electrolytic solution, and terminal leads at a particular frequency. ESR acts like a resistor in series with a pure non-resistive capacitor (thus the name Equivalent Series Resistance).

A LiPo is very similar to a large capacitor in many ways in regard to internal impedance effects. We generally ignore any AC (out of phase) effects since it is supplying DC current so ESR becomes the DC Internal Resistance of the battery -commonly called IR. Wayme used the technically correct term for the meter but it does in fact only measure resistance using DC. Some IR meters use a specific frequency as the standard to specify the resistance (1kHz from memory but I'm no expert on this).

The value of IR you get depends on the frequency you measure it at (and a host of other things). This meter measures it under the conditions that interest us. Supplying DC.
Originally Posted by Aviefly View Post
A couple of questions. First is probably easy for most but what does ESR stand for?
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