Battery Internal Resistance Tester Principle

1. Principle of the 4-terminal testing method

An AC current I, with a flow frequency of 1KHz, passes between the positive and negative electrodes of the battery. The alternating voltage difference V between the battery's positive and negative poles is measured, and the internal resistance of the battery is calculated using the formula R=V/I. To ensure measurement accuracy, the two current poles (S) and the two voltage poles (P) should be independently connected to the battery's positive and negative poles, free from wire resistance or contact resistance, to obtain the correct measurement value.

2. Voltage Measurement Principle

The sampling resistor voltage divider filters out noise, and the ADC samples the signal. After programming calculation and correction, the measured value is obtained.

3. Temperature Measurement Principle

A voltage divider network composed of an NTC temperature sensor and a constant Rx, where the NTC's resistance varies with temperature, allowing for the actual temperature value to be obtained by measuring the voltage across the divider and applying it to the NTC temperature conversion formula.