In recent years, with the expansion of user communication requirements and the improvement of service levels, mobile communication networks have rapidly extended to the countryside. In many outdoor-type marginal base stations, large quantities of colloidal batteries are used as the basic protection power source. Since the base station of this type is completely exposed in the wild, it has been found in maintenance practice that in the high temperature environment in the south, the bulging phenomenon of the shell of the colloidal battery occurs, which has a great influence on the life of the battery and the reliability of the communication power supply.
Analysis of the Causes of Bulging of Colloidal Batteries
The electrolyte of the colloidal battery is solidified in the form of a gel between the positive and negative electrode plates of the battery and the separator, so that the electrolyte does not flow, and has the advantages of high reliability, high charging efficiency, and long service life under high temperature environment. At the same time, it also has significant advantages in terms of energy saving and pollution reduction.
In the maintenance practice, it was found that about six months after the installation and use of the colloidal battery, the bulging situation of the individual colloidal battery cases was very serious: the side walls and the cover of the battery had different degrees of bulging; the leakage of the safety valve was very obvious, and the battery cover was The distribution of traces of the acid is basically "sprayed" around the safety valve; the battery leakage causes the battery compartment to be rusted; the safety valve cracks.
From the maintenance records and the analysis of the scene, the reasons for this phenomenon are mainly the following aspects:
First, safety valve external exhaust is not smooth. The safety valve has the function of adjusting the internal pressure of the battery. Under normal circumstances, it should be able to release the internal gas in time. At the initial stage of use, the colloidal battery has a relatively rich gas in the charging process because the electrolyte inside the battery is relatively "rich". If there is a problem with the safety valve and the exhaust gas is not smooth, when the battery discharges a large amount of gas during the charging process, it will cause the housing to bulge due to "flatulence", and even the safety valve opening will crack.
Second, the switching power supply system battery management program chip parameter design does not match the characteristics of the use of colloidal batteries. By contrasting the switching power supply parameter setting of the bulging battery site and the unswollen battery site switching power supply parameter setting, it was found that the switching power supply manufacturers of the battery bulging site designed a freewheeling equalizing function in order to allow the battery to be fully charged (ie, after the charging is completed, a small current is used. Continue to charge the battery). When the battery's charge flow is reduced to the 10mA/Ah conversion condition, the charge is not converted to the float charge process, but the freewheeling equalization is also required (the charge current at the freewheeling stage may also be reduced at high temperatures. The rally rises and the average freewheeling time is generally 4 to 10 hours. In addition to the poor power supply conditions of outdoor base stations, frequent power outages will inevitably result in the overcharging of the battery each time the switching power supply is fully charged, and also accelerates the corrosion rate of the battery electrode and the loss of water of the battery. The high temperature inside the battery causes the battery to bulge.
3. The temperature sensing line of the gel battery compartment is not connected, and the system cannot achieve the conversion from the equalization charge to the float charge when the temperature reaches 40°C. In the high-temperature environment, the failure of the temperature compensation function actually raises the total float charge voltage of the battery pack. This directly leads to the fact that the final charge current of the battery cannot be reduced. Instead, the charge current is increased by a multiple, and the internal analysis of the battery is continuously affected. Gas and heat, which exacerbated the electrolysis of the colloidal electrolyte water, causing the battery to bulge.
Fourth, poor battery ventilation. The design of the battery cabinet due to the full consideration of anti-theft security, resulting in the battery pack ventilation and natural cooling capacity is poor, the temperature generated by the battery pack during the charging process can not be timely diffusion, which also has a certain impact on the battery casing bulging.
Colloidal battery expansion solution
Based on the above analysis, during the maintenance work, we summarized the solution to the bulging of colloidal batteries. On the one hand, according to the characteristics of the colloidal battery, the battery charging management software of the switching power supply is changed as follows:
First, in order to shorten the equalization time and avoid battery bloat caused by overcharge, reset the float switching conditions and change the original setting current value of 10mA/Ah as the equalizing charge conversion condition to the system when the current value drops to 20mA/Ah. That is automatically converted to floating charge operation.
Second, the temperature sensor of the switching power supply is connected to the battery cabinet, so that the floating voltage of the switching power supply can be adjusted with the ambient temperature. Over-temperature protection is added. When the temperature reaches 40°C, the system automatically switches to floating charge operation to avoid battery bulging caused by continuous high-current charging.
Third, in order to prevent the battery from overcharging and shorten the equalization protection time, the equalization protection time is changed from 18 hours to 10 hours (equalization protection time setting is to prevent the battery from thermal runaway, when the average charging current cannot be reduced to the setting When the floating charge converts the current value, the system will be forced to float charge within the specified time).
Fourth, to extend the regular average charge cycle to avoid over-frequency high current charge. Change the original average setting time from 100 days to 180 days.
5. Cancel the freewheeling equalizing function of the switching power supply to avoid battery bulging caused by overcharging.
Through the above modification of the battery charging parameters, it is mainly to avoid overcharging the colloidal battery by the switching power supply under the condition that the battery is fully charged.
On the other hand, in order to prevent the exhaust valve from being unsmooth due to the quality problems of the safety valve, it is necessary to pay attention to the inspection of the safety valve in the daily inspection, and at the same time require the battery manufacturer to further improve the quality inspection and manufacturing process of the safety valve to ensure that the safety valve is After reaching the opening threshold, the valve can be normally opened and exhausted.
Through the above processing, after a period of observation, the colloidal battery no longer has shell bulging and the operation is in a normal state.
To sum up, under the high temperature environment in the south, according to the characteristics of the colloidal battery, under the condition that the battery is fully charged, the threshold current value and equal charge protection time of the charge-to-float charge should be reasonably set to prevent the battery from overcharging. Bulging of the battery case, at the same time to do a good job of battery over-temperature protection and strengthen the inspection of the safety valve, found that the problem must be rectified in a timely manner to improve the efficiency and service life of colloidal batteries. In this way, the advantages of energy saving, reduction of lead and acid pollution in colloidal batteries are fully realized.
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