Analyze the battery internal resistance measurement method

1. The method of measuring the internal resistance of DC discharge. According to the physical formula Ru003dV/I, the battery test device allows forcing a large constant DC current through the battery in a short period of time (generally 2-3 seconds) (currently 40-80 large currents are usually used) to measure the battery The voltage at both ends, and calculate the current internal resistance of the battery according to the formula. The accuracy of this measurement method is relatively high. If properly controlled, the measurement accuracy error can be controlled within 0.1%. However, this method has obvious disadvantages: (1) It can only measure large-capacity batteries or accumulators, and small-capacity batteries cannot load a large current of 40a-80a within 2-3 seconds; (2) When the battery passes a large current, The electrodes inside the battery will be polarized, resulting in polarization resistance. Therefore, the measurement time must be very short, otherwise the measured internal resistance has a large error; (3) The large current through the battery damages the internal electrodes of the battery to a certain extent. 2. Measurement method of AC pressure drop internal resistance. Since the battery is actually equivalent to an active resistor, we apply a fixed frequency and a fixed current to the battery (currently 1KHZ frequency and 50mA small current are generally used), and then sample the voltage. After a series of processing such as rectification and filtering, the internal resistance of the battery is calculated through the operational amplifier circuit. The battery measurement time of AC voltage drop internal resistance measurement is very short, generally about 100 milliseconds, and it can be measured almost by pressing the measurement switch. Haha. The accuracy of this measurement method is also very good, and the measurement accuracy error is generally between 1% and 2%. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: Why do solar street lights choose lithium batteries?