How to prolong the battery life of the power supply of the base station

The battery capacity of the base station Shengyang battery generally drops too fast and its service life is short. In a short period of one to two years, the capacity of the battery is only 30% - 40% of the nominal capacity, and some are only 10% - 20%. However, most of the base station batteries have been operated for one to four years, and their capacity is only about 50% of the nominal capacity, which is far from the designed service life. Compared with the same battery in the exchange station, its service life is also greatly reduced. This paper analyzes the causes of battery damage during the operation of base station power supply, and puts forward the methods to extend the service life of base station battery.

Definition of Shengyang battery life

The life of battery generally refers to the service life under floating charge. For the battery working in the non floating state, its life is measured from two dimensions of cycle discharge times and discharge depth, as shown in Table 1. Therefore, the battery life can not be simply measured by how many years it can be used.

For the cycle discharge times of the battery, it must be sufficient electric energy after the battery is discharged, and the charging time of sufficient electric energy shall be at least 24 hours (according to the provisions of YD / t799-2002). For the case of insufficient charging, it is difficult to determine the cycle discharge times, which must be lower than the data described in Table 1.

The effect of discharge depth on battery service life is also very large. The deeper the battery discharge depth is, the fewer times it will be recycled, as shown in Table 1. Therefore, deep discharge should be avoided in use.

Factors of end of life of Shengyang battery

For VRLA batteries, there are four failure modes: positive plate corrosion, water loss, thermal runaway, sulfation. Due to the improvement of alloy technology, the corrosion rate of positive grid is very slow, generally 10-15 years.

There are many ways to lose water: unreasonable design of throttle valve, frequent opening; frequent equalizing charge of battery by power supply; high ambient temperature. Among them, high temperature is the most important factor, which will accelerate the water loss speed of the battery and lead to the decrease of battery capacity. Based on 25 ℃, when the operating environment of the battery increases by 10 ℃, its service life decreases by 50%, as shown in Figure 1.

Thermal runaway refers to that the heat generated in the charging process of Shengyang battery is not released in time, forming a positive feedback between temperature and chemical reaction, resulting in runaway. Thermal runaway is destructive to the battery, which results in the deformation of the battery shell and the explosion of the battery. The causes of thermal runaway are that the ambient temperature of the machine room exceeds 45 ℃, the floating charge voltage is too high under high temperature (without temperature compensation function), and the charging current exceeds the design value (more than 2.5c10).

Sulfation refers to the formation of white and hard lead sulfate crystal on the plate, with large particles and low activity, which is difficult to be converted into active substances when charging, leading to the decline of battery capacity or function. The reason of hydrochloric acid is that the battery has been in storage for a long time (more than 3 months) before installation and use, has been continuously over discharged or frequently over discharged or under discharged with small current, the environment temperature is too high or too low, frequently under charged and has not been equalized regularly.

Factors affecting battery life of base station

Many base stations are located in remote locations, with unstable AC power supply or frequent power outages, or even no AC power at all; the base stations have no air conditioning or outdoor stations, with high ambient temperature; the stations are remote and large in number, so it is impossible to achieve refined maintenance. The above is the basic condition of the battery working environment of the base station.

Based on the analysis of the battery damage of base stations in China, the samples of battery damage in Xinjiang, Zhejiang, Shaanxi and Yunnan provinces were collected for analysis, and combined with the damage data of base station power supply in Vietnam, Egypt, Pakistan and Ethiopia, we concluded that the following factors affect the battery operation life:

1. Frequent AC power failure

Frequent blackout, long blackout time and irregular blackout time make the battery charge and discharge frequently, or there is no AC power at all in the base station. Alternating power supply through diesel generator and battery is the main reason that causes the battery capacity to drop too fast and the service life to shorten.

The outage frequency of the base station is too high, several times in a day, or even several days in a row, which makes the battery of the base station discharge again without sufficient power after discharge, and the battery is under charged for a long time. If undercharge occurs for many times in a row, it will lead to accumulated loss of battery capacity, aggravation of sulfation, decrease of battery capacity in a short period of time and end of service life.

2. The storage time of Shengyang battery is too long

There is self discharge in the storage process of the battery. If it is not supplemented for a long time, sulfation will occur. If this phenomenon is not improved in time, the battery capacity will be reduced or even damaged. In the storage process of the battery, the environmental temperature has a great influence on the capacity, as shown in Table 2.

3. The ambient temperature of the base station is too high

After the power failure of the base station, the air conditioner stops. Because the base station is a closed computer room, the indoor temperature of the base station will rise significantly. The high temperature makes the internal water loss of the valve controlled sealed battery increase, and the decrease of the electrolyte saturation (the decrease of the electrolyte in the glass fiber cotton diaphragm) makes the battery capacity decrease and shortens the service life.

4. Battery installation and opening quality

Whether the installation of Shengyang battery conforms to the specification has a great impact on the use mission of the battery. During installation, the fixing screw of the connector between the batteries is not tightened, the contact resistance between the terminal and the connector increases, which will generate a lot of heat during charging and discharging and burn out.