To measure the internal resistance of a battery, there are two methods, one is the AC method and the other is the DC method.

The so-called ACIR is the value of internal resistance of the battery measured by AC method. The measurement principle of ACIR is that the measurement current is applied with a measurement frequency of 1 kHz and the internal resistance of the battery is calculated from the voltage value of the AC voltmeter.

Figure 1. Battery ACIR measurement method

1. Features of the battery ACIR measurement:

1.1 The battery ACIR test results are highly reproducible.

1.2 ACIR measurements are fast, with test times in the millisecond range. Highly efficient batch measurement can be achieved by pairing with automated equipment, also known as battery sorting machine.

1.3 The ACIR tester is small and lightweight, and the testing process is energy efficient.

1.4 It can achieve fast measurement, especially suitable for battery incoming inspection and battery cell grouping test.

The so-called DCIR is the value of internal resistance of the battery measured by DC method. The measurement principle of DCIR is to connect a load and measure the resistance value according to the change of voltage and current.

Figure 2. Battery DCIR measurement method

2. Features of the battery DCIR measurement:

2.1 Compared to ACIR, the DCIR test results for batteries are relatively less reproducible.

2.2 Battery DCIR measurement takes more time and requires charge/discharge test of the battery to be calculated.

2.3 DCIR testers, also known as battery charging and discharging equipment, are larger, heavier and more power hungry than ACIR testers.

2.4 Compared to ACIR, DCIR will be closer to the internal resistance of the battery during actual operation.

In summary, ACIR and DCIR have a complementary relationship, and it’s recommended to choose the one that best suits your application, or to carry out both measurements.

WinAck Group can provide complete battery test equipment solutions. Come by, contact us for a solution that can help you succeed. For better batteries, Win & Ack!