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Author ：Iflowpower – Portable Power Station Supplier
How to measure the internal resistance of the UPS battery? Different types of battery internal resistance. Measuring the ohmic electrical resistance of the lead-acid battery to detect the technical state of the battery, the use of this method is increasingly popular. Under normal circumstances, the internal resistance of the UPS battery is strong, and the internal power discharge capacity is weak.
Internal resistance is an important technical indicator for measuring the performance of UPS batteries. How to measure the internal resistance of the UPS battery? The UPS Battery Internal Resistance Analyzer is an ideal test tool for maintenance, troubleshooting and performance testing of single fixed batteries and battery packs used in important battery backup applications such as data centers, telecommunications networks, power distribution systems. We generally take the resistors of the UPS battery to two states: charge state internal resistance and discharge state internal resistance.
The charge state embodies the measured battery internal resistance when the UPS battery is completely charged. The internal resistance of the discharge refers to the battery internal resistance measured after the UPS battery is fully discharged (when discharging to standard cutoff voltage). In general, the internal resistance of the discharge is unstable.
The results of the measurement are much higher than the normal value, and the charge state is more stable, and the measurement is actually the actual significance. Therefore, during the measurement of the UPS battery, we all made the measurement standard in the charge state. In general measuring occasions, we require the internal resistance measurement accuracy error of the UPS battery must be controlled within 5% of the positive and negatives.
Such a small resistance and such accurate requirements must be measured with a dedicated instrument. Battery internal resistance measurement method 1. DC discharge internal resistance measurement.
According to the physical formula R = U / I, the test device allows the battery to force the battery through a large constant DC current (currently using a large current of 40A to 80A) in a short period of time (currently using a large current of 40A to 80A), and measure the battery. The voltage at both ends and calculates the current battery internal resistance according to the formula. The accuracy of this measurement method is high and controlled.
The measurement accuracy error can be controlled within 0.1%. 2.
AC pressure drop internal resistance measurement. Because the UPS battery is actually equivalent to an active resistor, we apply a fixed frequency and fixed current to the battery (currently using a 1kHz frequency, 50mA small current), then sample the voltage, and is rectified, filtered. After processing, the internal resistance value of the battery is calculated by the op amp circuit.
The battery measurement time of the AC pressure dropped internal resistance method is extremely short, generally in 100 milliseconds. This accuracy of this measurement method is also good, and the measurement accuracy error is generally between 1% to 2%. The advantages and disadvantages of this method: almost all batteries can be measured using an alternating internal resistance measurement method, including small capacity batteries.
The internal resistance measurement of the laptop battery cell is generally in this way. The measurement accuracy of the AC pressure drop measurement method is likely to be affected by the ripple current, as well as harmonic current interference. This is a test for the anti-interference ability in the measuring instrument circuit.
Use this method to measure, there will be no too much damage to the battery itself. The measurement accuracy of the AC pressure drop measurement method is not as good as DC discharge internal resistance measurement. 3.
Ohm measurement. The correct way to use ohm read should be, use it as a tool for detecting a change in the battery of the battery, using it to determine the backward battery and the hidden dangers in the battery pack in the floating state. When the UPS battery pack is installed and stabilized, we collect a set of initial ohmic electrical readings.
Because of this stage, in the state of charge, the purity of lead, the status of the combination, gel stability, etc. will change significantly. Related to the initial reading, 50% changed changes often occur.
If some batteries exceed this data, it is necessary to make a balance charging of the battery pack, there may be one capacity test. The above is the method of UPS battery internal resistance, one of the important signs of the battery state is its internal resistance, if the battery failure or capacity is insufficient, it is possible to cause major accidents, so it is necessary to perform comprehensive online monitoring of the operating parameters of the battery. Evaluate its working status.
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