1.2V Ni-MH battery

　　Several charging methods for 1.2V Ni-MH battery and how to reduce faults?

　　There are 6 charging methods for 1.2V Ni-MH battery, namely smart charging, constant voltage and current limiting charging, constant voltage charging, constant current charging, balanced charging and fast charging. In addition, the way to reduce UPS battery failure is to check regularly and in a suitable temperature environment Recharge, less deep discharge. Next, I will introduce the detailed content to you.

　　1. Charging method of UPS battery

　　1. Constant current charging

　　Constant current charging uses a segmented constant current method to charge. This is generally achieved by adjusting the charging device itself. The charging current can be selected and adjusted arbitrarily, and it has strong adaptability. It is especially suitable for charging with low current for a long time, and is also conducive to charging 1.2V Ni-MH battery with slow capacity recovery. The disadvantage is that the initial charging current is too small, and the charging current is too large in the later stage of charging. The charging time is long, there is a lot of precipitated gas, the impact on the electrode plates is large, the energy consumption is high, and the efficiency is low (not more than 65%). During the charging process It needs to be watched by someone, and is generally used during initial charging and desulfurization charging at low current. Since the variant of constant current charging is segmented constant current charging, in order to avoid excessive current in the later stage of charging, the charging current should be adjusted in time. Attention should also be paid to the size of the charging current, charging time, timing of current conversion, and charging termination voltage. Select etc.

　　2. Constant voltage charging

　　Constant voltage charging means that each single-cell UPS battery is charged at a constant voltage (generally the number of single-cell batteries multiplied by 2.5v). The characteristics are: the initial charging current is quite large, the electromotive force of the UPS battery and the relative density of the electrolyte rise rapidly. As charging continues, the charging current gradually decreases. At the end of the charging period, only a small current passes through. The charging time is short and the energy consumption is high. Low, generally charging the UPS battery for 4 to 5 hours can obtain 90% to 95% of its capacity. If the charging voltage is properly selected, the entire charging process can be completed in 8 hours, and the entire charging process does not require human supervision. This charging method is widely used in Recharge. Since the initial charging current is too large, charging a UPS battery with excessive discharge depth will cause the initial charging current to rise sharply, which may easily cause overcurrent of the charged UPS battery or damage to the charging equipment. Since the charging current cannot be adjusted during the charging process, it is not suitable for initial charging and desulfurization charging of 1.2V Ni-MH battery. It is difficult to compensate for changes in the UPS battery voltage during the charging process, so it is difficult to fully charge the UPS battery with slow capacity recovery.

　　3. Fast charging

　　Fast charging refers to a charging method with high current. Fast charging does not produce a large number of bubbles and does not generate heat, thus shortening the charging time. At present, there are two types of commonly used fast charging: pulse charging and high current decrement fast charging.

　　4. Balanced charging

　　Balanced charging is a 1-3h charging process with a small current (1/20C20A). It is mainly used to eliminate the difference caused by the imbalance of the whole set of batteries due to some reasons under the same operating conditions of the UPS battery in a set of floating charging operation (that is, the DC power supply and the UPS battery are connected in parallel), so as to achieve the best performance of the whole set. Battery balancing. This method generally cannot be used frequently, but when the UPS battery encounters one of the following conditions.

　　5. Constant voltage and current limited charging

　　Constant voltage and current limiting charging is mainly used to remedy the shortcoming of excessive charging current during constant voltage charging (the method is the same as constant voltage charging). The charging is automatically adjusted by connecting a resistor (current limiting resistor) in series between the charging power supply and the UPS battery being charged. current. When the charging current is too large, the voltage drop across the current-limiting resistor is also large, thereby reducing the charging voltage. When the charging voltage is too small, the voltage drop across the current-limiting resistor is also small, and the voltage loss output by the charging device is also small. , thus automatically adjusting the charging current so that it does not exceed a certain limit. This method is currently widely used for initial charging of maintenance-free batteries and supplementary charging of ordinary 1.2V Ni-MH battery.

　　6. Smart charging

　　Smart charging is currently the most advanced charging method. The principle is to dynamically track the acceptable charging current of the UPS battery during the entire charging process. Apply du/dt technology, that is, the charging power supply automatically determines the charging process parameters according to the state of the UPS battery, so that the charging current is kept near the acceptable charging current curve of the UPS battery from beginning to end, and the UPS battery is charged almost without gas precipitation, thus Protect 1.2V Ni-MH battery. This method is suitable for charging 1.2V Ni-MH battery in various states and types, and is safe, reliable, time-saving and energy-saving.

　　2. Methods to reduce UPS battery failures

　　1. Regular inspection

　　Regularly check the terminal voltage and internal resistance of each unit battery. For 12V unit batteries, if it is found during inspection that the terminal voltage difference between each unit battery exceeds 0.4V or the internal resistance of the battery exceeds 80mΩ, each unit battery should be balanced and charged to restore the internal resistance of the battery. and eliminate the terminal voltage imbalance between each unit cell. During balanced charging, the charging voltage can be 13.5~13.8V. Most batteries that have been well balanced and charged can restore their internal resistance to less than 30mΩ.

　　2. Maintain a suitable ambient temperature

　　The main factor affecting battery life is ambient temperature. Generally, the best ambient temperature required by battery manufacturers is between 20-25°C. Although the increase in temperature improves the battery's discharge capacity, the price paid is that the battery life is greatly shortened.

　　3. Charge and discharge regularly

　　The float voltage and discharge voltage in the UPS battery have been adjusted to the rated value when leaving the factory, and the size of the discharge current increases with the increase of the load. The load should be adjusted reasonably during use, such as controlling electronic equipment such as microcomputers. Use the number of units. Under normal circumstances, the load should not exceed 60% of the UPS rated load. Within this scheme, the battery's discharge current will not be over-discharged.

　　4. Reduce deep discharge

　　The service life of a battery is closely related to the depth to which it is discharged. The lighter the load carried by the UPS battery, the greater the ratio of its available storage capacity to its rated capacity when the mains power supply is interrupted. In this case, when the UPS battery automatically shuts down due to low battery voltage, the battery is The depth of discharge is relatively deep.

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