[Repost] 5 ways to reduce the total failure rate of UPS power supply

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[Repost] 5 ways to reduce the total failure rate of UPS power supply [Copy link]

1. Charge during peak power supply hours For users whose UPS power supply is in a low-voltage power supply or has frequent power outages for a long time, in order to prevent the battery from being damaged prematurely due to long-term insufficient charging, the battery should be charged during peak power supply hours (such as late at night) to ensure that the battery has enough charging time after each discharge. Generally, after a battery is deeply discharged, it takes at least 10 to 12 hours to charge to 90% of the rated capacity. Pay attention to the selection of chargers. The maintenance-free sealed batteries used in UPS power supplies cannot be charged with a thyristor-type "fast charger". This is because this charger will cause the battery to be in a bad charging state of both "instantaneous overcurrent charging" and "instantaneous overvoltage charging". This state will greatly reduce the available capacity of the battery, and in severe cases, the battery will be scrapped. When using a UPS power supply with a constant voltage cut-off charging circuit, be careful not to adjust the battery voltage under-voltage protection working point too low, otherwise, it is easy to produce overcurrent charging in the early stage of charging. Of course, it is best to use a charger with both constant current and constant voltage to charge it.

2. Ensure the power supply environment temperature

The available capacity of the battery is closely related to the ambient temperature. In general, the performance parameters of the battery are calibrated at room temperature of 20℃. When the temperature is below 20℃, the available capacity of the battery will decrease, and when the temperature is above 20℃, the available capacity will increase slightly. Batteries of different manufacturers and models are affected by temperature to different degrees. According to statistics, at -20℃, the available capacity of the battery can only reach about 60% of the nominal capacity. It can be seen that the influence of temperature cannot be ignored.

Of course, to extend the service life of the battery pack, not only should attention be paid to maintenance and use, but also the load characteristics (resistance, inductance, capacitance) and size should be fully considered when selecting. Do not keep the battery in an excessively light load for a long time, so as to avoid the battery discharge current being too small and causing the battery to be scrapped. 3. Regular inspection Regularly check the terminal voltage and internal resistance of each unit battery. For 12V unit batteries, if the terminal voltage difference between each unit battery is found to be more than 0.4V or the internal resistance of the battery is more than 80mΩ, each unit battery should be balanced charged to restore the internal resistance of the battery and eliminate the terminal voltage imbalance between each unit battery. The charging voltage during balanced charging is 13.5~13.8V. Most batteries that have been well balanced charged can restore their internal resistance to less than 30mΩ.

During the operation of the UPS power supply, the above-mentioned imbalance caused by the change of the characteristics of each unit battery over time cannot be eliminated by relying on the charging circuit inside the UPS power supply. Therefore, if the battery pack with obvious imbalance in characteristics is not promptly treated with offline equalization, the imbalance will become more and more serious.

4. Re-floating charge

The UPS power supply uses the charging circuit of the internal charging sub-product to recharge the battery for more than 10 to 12 hours before running under load. The UPS power supply is in a floating charge state for a long time without a discharge process, which is equivalent to being in a "storage standby" state. If this state lasts too long, the battery will fail and be scrapped due to "too long storage". It is mainly manifested in an increase in the internal resistance of the battery. In severe cases, the internal resistance can reach several Ω.

People have found that: at room temperature of 20°C, after 1 month of storage, the battery's available capacity is about 97% of its rated value. If it is stored for 6 months without use, its available capacity becomes 80% of the rated capacity. If the storage temperature rises, its available capacity will also decrease. Therefore, it is recommended that users intentionally unplug the AC input every 20°C months to allow the UPS power supply to work in a state where the battery provides energy to the inverter. But this operation should not be too long. When the load is about 30% of the rated output, it is sufficient to discharge for about 10 minutes. 5. Reduce the depth of discharge The service life of the battery is closely related to the depth of its discharge. The lighter the load carried by the UPS power supply, the greater the ratio of its available capacity to its rated capacity when the mains power supply is interrupted. In this case, when the UPS power supply automatically shuts down due to low battery voltage, the depth of battery discharge is relatively deep.

How to reduce the occurrence of deep discharge of batteries in actual process? The method is very simple: when the UPS power supply is in the state of interruption of mains power supply and the battery supplies power to the inverter, most UPS power supplies will periodically sound an alarm with an interval of about 4 seconds to inform the user that the battery is now providing energy. When the alarm sound becomes rapid, it means that the power supply is in deep discharge, and emergency treatment should be carried out immediately to turn off the UPS power supply. Unless it is absolutely necessary, generally do not let the UPS power supply work until it automatically shuts down due to low battery voltage.

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qdchina

Very good, very detailed and in-depth

shakencity

For users whose UPS power supply is in a low voltage supply of the mains for a long time or has frequent power outages, in order to prevent the battery from being damaged prematurely due to long-term insufficient charging, the battery should be charged at peak power supply times (such as late at night) to ensure that the battery has enough charging time after each discharge. Generally, after the battery is deeply discharged, it takes at least 10 to 12 hours to charge to 90% of the rated capacity. Pay attention to the selection of the charger.