Extend the life of the battery pack in the UPS

Extend the life of the battery pack in the UPS

Reprinted from: http://www.maigoo.com/zhishi/55318.html

Updated on: 11:32:13 by member Liang haini

 

Abstract: rechargeable battery installation-maintenance-after-sales: this article describes how to regularly check the terminal voltage and internal resistance of each battery unit, refresh the battery, reduce the deep discharge, and extend the battery life of the ups by charging at the peak of the power supply.

 

 

Extend the life of the battery pack in the UPS

In-line UPS power supply, because of its reasonable circuit design and the large margin of the driving power element capacity, the power circuit failure rate is very low. In contrast, the failure rate caused by the battery pack is increased to more than 60%. It can be seen that correct use and maintenance of the battery is one of the key factors to prolong the life of the battery pack and reduce the total failure rate of the UPS power supply.

1. regularly check the terminal voltage and internal resistance of each battery unit. For a 12 V unit battery, if the terminal voltage difference between battery units exceeds V or the internal resistance of the battery unit exceeds 80 m Ω during the check, battery should be balanced to recover the internal resistance of the battery and eliminate the terminal voltage imbalance between battery units. The charging voltage is 13.5 ~ 13.8v. The vast majority of batteries that have been well balanced charging can recover their internal resistance to below 30mΩ.
During the UPS power supply operation, the above imbalance arising from the change of battery characteristics of each unit over time cannot be eliminated by the internal charging circuit of the UPS power supply, therefore, a battery pack with obvious imbalance has occurred for this feature. If the battery is not fully loaded offline in time, the imbalance will become more and more serious.

2. Refresh the instance and shut down the ups for more than 10 days. Before restarting the instance, the UPS power should be started without load to use the charging circuit in the machine to recharge the battery 10 ~ After 12 hours or more, run the task with load.

The UPS power supply remains in the floating-charging status for a long time without discharge, which is equivalent to the "available for storage" state. If this state lasts for a long time, the battery will be decommissioned due to "storage for too long". It mainly shows that the internal resistance of the battery increases, and the internal resistance can reach several Ω in severe cases.

We found that at room temperature of 20 ℃, after one month of storage, the battery capacity is about 97% of its rated value. If it is not used for 6 months, its available capacity is changed to 80% of its rated capacity. If the storage temperature increases, its available capacity will also decrease.

Therefore, it is recommended that the user intentionally unplug the mains input every 20 °C months so that the UPS power can work in the State where the battery supplies energy to the inverter. However, this operation should not take too long. When the load is about 30% of the rated output, it can be discharged for about 10 minutes.

3. Reduce deep discharge. The service life of the battery is closely related to the depth of discharge. The load of the UPS power supply is lighter. When the mains supply is interrupted, the greater the ratio of the available power storage capacity to its rated capacity, in this case, when the UPS power supply is automatically shut down because of the low battery voltage, the depth of the battery discharge is relatively deep.

How can we reduce the occurrence of deep discharge on the battery in the actual process? The method is simple: when the UPS power supply is interrupted by the mains supply and the battery is switched to the inverter power supply status, the majority of UPS power supplies will trigger a periodic alarm with a gap of about 4 s, inform the user that the battery is currently providing energy. When the alarm changes rapidly, it indicates that the power supply is already in deep discharge, and emergency treatment should be performed immediately to turn off the UPS power supply. Generally, do not let the UPS power supply work until it is automatically shut down because of the low battery voltage.

4. Use the power supply peak for charging. For the UPS power supply that has been in the mains supply for a long time, low-voltage power supply or frequent power outages, to prevent premature damage to the battery due to long-term insufficient charging, fully utilize the power supply peak (such as late night time) to charge the battery to ensure sufficient charging time after each discharge. Generally, after the battery is deeply discharged, it takes at least 10 ~ to charge it to 90% of the rated capacity ~ Around 12 hours.

5. Pay attention to the charger selection. The maintenance-free and sealed battery for UPS power supply cannot be charged with a Thyristor-type "quick charger. This is because the charger will cause the battery to be in both "instantaneous over-current charging" and "instantaneous over-voltage charging" bad charging status. This State will greatly reduce the battery available capacity, and in severe cases, the battery will be decommissioned. When using the UPS power supply of the constant voltage cutoff charging circuit, be careful not to adjust the battery voltage too low protection work point too low, otherwise, it is easy to generate an over-current charging in the initial charging. Of course, it is best to choose a charger with both constant current and constant pressure to charge it.

6. Ensure the ambient temperature of the power supply. The available battery capacity is closely related to the ambient temperature. Generally, the performance parameters of the battery are calibrated at a temperature of 20 ℃. When the temperature is lower than 20 ℃, the available capacity of the battery will be reduced, when the temperature is higher than 20 ℃, the available capacity will increase slightly. Different manufacturers of different types of battery vary depending on the temperature. According to statistics, at-20 ℃, the battery available capacity can only reach about 60% of the nominal capacity. The effect of visible temperature cannot be ignored.

Of course, to extend the service life of the battery pack, we should not only pay attention to the maintenance and use, but also fully consider the load characteristics (resistance, inductance, capacitance) and size when selecting. Do not run the battery excessively lightly for a long time to prevent the battery from being decommissioned due to the excessive discharge current of the battery.