How to Reduce UPS Power Supply Failure Rate and Extend Electrical Battery Packs Life

Through the statistics of various faults in UPS power supply maintenance work, it can be concluded that the faults caused by the electrical battery in the backup UPS power supply exceed 50% of the total faults. On-line UPS power supply, because its circuit design is reasonable, and the capacity of driving power components is large, so the failure rate of power supply circuit is very low. In contrast, the failure rate caused by electrical battery packs rises to more than 60%. It can be seen that the correct use and maintenance of the electrical battery is one of the key factors to prolong the life of the electrical battery pack and reduce the total failure rate of the UPS power supply.

Ⅰ. Regularly check the UPS power supply electrical battery

1. Periodically check the terminal voltage and internal resistance of each unit electrical battery. For the 12V unit electrical battery, if the terminal voltage difference between the unit electrical batteries exceeds 0.4V or the internal resistance of the electric power exceeds 80mΩ or more during the inspection, the unit cells should be balanced and charged to restore the internal resistance of the electrical battery and eliminate the terminal voltage imbalance between the unit electrical batteries. The charging voltage can be taken as 13.5~13.8V during equalization charging. Most of the electrical batteries that have been solved by good equalization charging can restore their internal resistance to below 30mΩ.

2. During the operation of the UPS power supply, the above-mentioned imbalance due to the change of the characteristics of each unit electrical battery over time cannot be eliminated by relying on the internal charging circuit of the UPS power supply. So for this feature has distinct imbalance of electrical battery packs, if the off-line equalization is not solved in time, the imbalance will become more and more serious.

Ⅱ. Re-float charging the UPS power supply electrical battery

1. The UPS power supply has been shut down for more than 10 days. Before restarting, the UPS power supply should be started without load to use the electric circuit of the charging sub-product in the machine to re-float the electrical battery for more than 10-12 hours and then run with load.

2. 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 state of "storage for use". If this state continues for too long, the electrical battery will fail due to "too long storage", which is mainly manifested as an increase in the internal resistance of the eletrical battery, and the internal resistance can reach several Ω in severe cases.

Ⅲ. Reduce the UPS power supply electrical battery deep discharge

1. The lifespan of an electrical battery is closely related to how deeply it is discharged. The lighter the load carried by the UPS power supply, when the mains power supply is interrupted, the greater the ratio of the available capacity of the storage battery to its rated capacity. In this case, when the UPS power supply automatically shuts down due to low battery voltage and the depth of discharge is relatively deep.

2. How to reduce the deep discharge of the electrical battery in the actual process? The solution is very simple: when the UPS power supply is interrupted by the mains power supply, and the electrical battery is switched to supply power to the inverter, most UPS power supplies will sound a periodic alarm sound every 4s or so to inform the user that the energy is currently supplied by the electrical battery. When the alarm sound becomes rapid, it means that the power supply is in deep discharge, and emergency solutions should be carried out immediately, and the UPS power supply should be closed. It is not unavoidable, generally do not let the UPS power supply work until the automatic shutdown because the electrical battery voltage is too low.

Ⅳ. Ensure the ambient temperature of the UPS power supply

The available capacity of the UPS power supply electrical battery is closely related to the ambient temperature. In general, the performance parameters of the battery are calibrated at a room temperature of 20 °C. When the temperature is lower than 20 °C, the available capacity of the battery will decrease, and when the temperature is higher than 20 °C, its available capacity will increase slightly. Different manufacturers and different types of batteries are affected by temperature differently. According to statistics, at -20 ℃, the usable capacity of the battery can only reach about 60% of the nominal capacity. The effect of visible temperature cannot be ignored.

In order to prolong the service life of the electrical battery pack, attention should not only be paid to maintenance and use, but also the load characteristics (resistive, inductive, capacitive) and size should be fully considered when selecting. Do not run the electrical battery under excessive light load for a long time, so as not to cause the electrical battery to be scrapped due to the small discharge current of the electrical battery.