How to Extend the Life of UPS Battery Pack and Reduce the Total Failure Rate of UPS Power Supply

A.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 its internal resistance exceeds 80m Ω, each unit battery should be charged evenly to restore the internal resistance of the battery and eliminate the terminal voltage imbalance between each unit battery. During balanced charging, the charging voltage should be between 13.5-13.8V. Most batteries that have undergone good balanced charging treatment can restore their internal resistance to below 30m Ω.

During the operation of UPS power supply, the above-mentioned imbalance caused by the changing characteristics of each unit battery over time cannot be eliminated by the internal charging circuit of UPS power supply. Therefore, for battery packs with obvious imbalance in these characteristics, if offline equalization charging is not taken in a timely manner, the imbalance will become increasingly serious.

B.Re float charging:

The UPS power supply has been shut down for more than 10 days. Before restarting, the UPS power supply should be started without adding load to use the charging circuit inside the machine to float charge the battery for more than 10-12 hours before running with 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 and standby" state. If this state persists for too long, causing the battery to fail and be scrapped due to "storage for too long", it is mainly manifested as an increase in internal resistance of the battery, and in severe cases, the internal resistance can reach several Ω.

We found that after being stored at room temperature of 20 ℃ for one month, the usable capacity of the battery is about 97% of its rated value. If stored for six months without use, its usable capacity becomes 80% of its rated capacity. If the storage temperature increases, its usable capacity will also decrease.

Therefore, it is recommended that users intentionally disconnect the mains input every 20 ° C months to allow the UPS power supply to operate in a state where energy is provided to the inverter by the battery. But this operation should not be carried out for too long. When the load is around 30% of the rated output, it can be discharged for about 10 minutes.

C.Reduce deep discharge:

The service life of electricity is closely related to the depth at which it is discharged. 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 the actual process? The method is simple: when the UPS power supply is interrupted by the mains power supply and the inverter is powered by the battery, the vast majority of UPS power supplies will sound a periodic alarm sound with a gap of about 4 seconds to notify the user that the energy is now provided by the battery. When the alarm sound becomes urgent, it indicates that the power supply is in deep discharge and emergency measures should be taken immediately to turn off the UPS power supply. It is not necessary to force it, generally do not let the UPS power supply work continuously until it automatically shuts down due to low battery voltage.

D.Charging during peak power supply periods:

For users who have been exposed to low voltage power supply or frequent power outages of UPS power supply for a long time, in order to prevent premature damage to the battery due to long-term insufficient charging, it is necessary to fully utilize the peak power supply (such as late night time) to charge the battery to ensure sufficient charging time after each discharge. After being deeply discharged, it usually takes at least 10-12 hours for a battery to be recharged to 90% of its rated capacity.

E.Pay attention to the selection of chargers:

The maintenance free sealed battery used for UPS power supply cannot be charged with a thyristor type "fast charger"

This is because this type of charger can cause the battery to be in a harsh charging state of both "instantaneous overcurrent charging" and "instantaneous overvoltage charging". This state can greatly reduce the available capacity of the battery, and in severe cases, it can render the battery useless. When using a UPS power supply with a constant voltage cutoff charging circuit, be careful not to set the low voltage protection working point of the battery too low, otherwise overcurrent charging may occur during its initial charging stage.

Of course, it is best to use a charger that has both constant current and constant voltage to charge it.

F.Ensure the ambient temperature of the power supply:

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

Of course, to extend the service life of a 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 keep the battery running under excessive light load for a long time, in order to prevent the battery from being scrapped due to insufficient discharge current.

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