Through the statistics of UPS uninterrupted power supply maintenance work, it can be concluded that for backup UPS power supply, the faults caused by batteries exceed 50% of the total faults; For online UPS, due to its reasonable circuit design, especially with the development of science and technology, most of them adopt integrated, modular, and intelligent UPS power supplies, and the configured backup capacity is relatively large, so there are few faults caused by the power supply. In contrast, faults caused by battery packs have increased to over 60%. It can be seen that the correct use and maintenance of batteries is a key factor in extending the lifespan of battery packs and reducing the failure rate of UPS power supply.
Simply put, batteries have three characteristics: large scale, high cost, and strong consumption. All you can do is find ways to extend the service life of batteries, which in fact increases the availability of data centers. Here are seven measures taken by data center equipment managers to expand the service life of their UPS batteries in data centers.
1、 Choose a moderately sized UPS battery for the data center
In most data centers, UPS can fully charge the battery within 20 minutes. This is called high load charging. Compared to low load charging, high load charging has thinner and more battery panels, but the service life of high load batteries is often shorter. There are many other factors to consider when purchasing UPS batteries, such as average lifespan, voltage specifications, front-end control, incidental costs, and other considerations. In addition, data center managers also need to consider other potential issues, such as battery sealing and internal connections.
2、 Properly install, operate, and maintain batteries
Incorrect installation and maintenance can shorten the service life of the battery. The so-called good maintenance measures are to provide good ventilation conditions for the battery, control the temperature as much as possible at around 77 degrees Fahrenheit, and ensure that the air temperature reaching all batteries in the battery pack is around 3 degrees Fahrenheit. In addition, it should also be ensured that some batteries in the battery pack do not age much faster than other batteries.
Why is this? Mixing batteries with different usage times and internal resistance sizes will accelerate their aging process. Regular inspections of batteries can solve various problems such as loose connections and poor sealing, which can lead to equipment corrosion and even lead to fires.
In addition, data center managers should also keep an eye on the discharge status of batteries at all times. If an empty battery is not charged within 48 hours, it will basically be scrapped. Excessive discharge of the battery can lead to repeated charging problems, and excessive discharge can also reduce the battery's service life.
3、 Monitoring of UPS battery capacity
Due to factors such as corrosion, the internal resistance of the battery will gradually increase. When the increase reaches 30%, it is time to replace it. Through capacity testing, this issue is easily detected. As most manufacturers say, when a battery's capacity drops to 80% of its original capacity, it should be replaced. Users should test their battery performance and capacity based on IEEE standards, preferably IEEE1180 or IEEE450.
4、 Regular charging and discharging
UPS is in a floating charge state for a long time without any discharge process, which is equivalent to being in a "storage standby" state. If this state persists for too long, it can cause the battery to become invalid and scrapped due to prolonged storage. This is mainly manifested by an increase in the internal resistance of the battery, which can reach several ohms in severe cases. At room temperature (20% 3), the usable capacity of the battery after one month of storage is about 97% of its rated value. If it is not used after 6 months of storage, its usable capacity becomes 80% of its rated capacity. If the storage temperature increases, its usable capacity will further decrease. Therefore, it is recommended to intentionally interrupt the mains power input every other month, allowing the UPS to operate in a state where the battery provides energy to the inverter. However, this operation should not take too long. It can be discharged for 10 minutes at around 30% of the rated output of the load.
5、 Reduce deep discharge
The service life of a battery is closely related to the depth of its discharge. The lighter the load carried by UPS, the greater the ratio of the usable capacity of the battery to its rated capacity when the mains power supply is interrupted. When UPS automatically shuts down due to low battery voltage, the depth of battery discharge is relatively deep. The way to reduce deep discharge of batteries in practical applications is to: when the mains power supply is interrupted and the inverter is powered by the battery, and when the UPS power supply alarms, it indicates that the battery is in a deep discharge state. Emergency measures should be taken immediately to shut down the UPS. If it is not a last resort, generally do not let the UPS work until it automatically shuts down due to low battery voltage.
6、 Charging when using electric power
For users of UPS who are in a long-term state of low voltage supply or frequent power outages, in order to prevent premature damage to the battery due to long-term insufficient charging, it is necessary to make full use of peak hours (such as late night time) to charge the battery, to ensure that the battery has sufficient charging time after each discharge. After being deeply discharged, it usually takes at least 10-12 hours for a battery to recharge to 90% of its rated capacity. Try to keep the battery in a fully charged state.
7、 Pay attention to the selection of chargers
The maintenance free sealed lead-acid battery used for UPS 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 at the same time. This state will greatly reduce the usable capacity of the battery, and in severe cases, it will cause the battery to be scrapped. When using a UPS with a constant voltage cutoff charging circuit, be careful not to set the working point of the battery voltage protection too low, otherwise overcurrent charging may occur in the early stages of charging. It is best to choose a charger with both constant current and constant voltage for charging.