Internal Resistance Test (AC and DC)

Internal Resistance Test (AC and DC)


The Internal Resistance (IR) of a battery is the opposition to the current flow through it. Two methods were used by IEC standard: the AC method or DC method. Thus it is used as ageneral guideline and can provide valuable information about the battery performance. The higher value of IR indicates battery reaching its end-of-life.

Procedure and Standard

Depending on the specified battery internal resistance in the manufacturers datasheet, the proper equipment was selected. For the DC test method, the internal resistance test are embedded into other test program, such as Auto or Cycle test. Thus it takes a few hours until the test is finished. For AC method, the internal resistance can be carried out individually so it only takes a few minutes.


Internal Resistance Method Cadex C7x00-C Cadex C8000 Cadex C5100B WMR CBAIV Vencon UBA Hioki BT3563-01
AC   Yes**       Yes
DC Yes Yes Yes Yes Yes  

**AC method using impedance test on channel #1 only.

Result Sample

The results in the table below are derived from testing on 12V SLA Panasonic LC-R127R2P1 batteries.

  Date Time AC Impedance (mΩ) Voltage (V)
1 01/22/2016 13:17:42 21.9 12.679
2 01/22/2016 13:17:47 21.2 12.663
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