6F22 carbon battery.Analysis of the causes of colloidal battery bulging

　　The electrolyte of the gel battery is solidified in a gel form between the positive and negative plates and the separator of the battery pole group, so that the electrolyte does not flow. It has the advantages of high recycling reliability in high temperature environments, high charging efficiency, and long service life. At the same time, it also has significant advantages in energy saving and pollution reduction.

　　During the maintenance practice, it was found that after about half a year of installation and use of the gel battery, the bulging of the shell of some gel batteries was very serious: the side walls and shell cover of the battery bulged to varying degrees; the leakage at the safety valve was very obvious, and the battery cover surface The acid traces are basically distributed in a "spray" shape with the safety valve as the center; battery leakage causes the battery compartment body to be rusted; and the safety valve mouth cracks.

　　From the analysis of maintenance records and on-site conditions, the main reasons for this phenomenon include the following aspects:

　　1. The safety valve does not exhaust smoothly to the outside. The safety valve has the function of adjusting the internal air pressure of the battery. Under normal circumstances, it should be able to release the internal gas in time. In the early days of use of gel batteries, because the electrolyte inside the battery is relatively "rich", a large amount of gas is released during the charging process. If there is a problem with the safety valve and the exhaust is not smooth, when the amount of gas released from the battery reaches a certain level during the charging process, the case will bulge due to "flatulence", and the safety valve port may even crack.

　　2. The parameter design of the battery management program chip of the switching power supply system is inconsistent with the usage characteristics of the gel battery. By comparing the parameter settings of the switching power supply at the bulging battery site and the switching power supply parameter setting at the uninflated battery site, it was found that the switching power supply manufacturer at the bulging battery site designed a freewheeling equalizing charging function (that is, using a small current after charging is completed) in order to fully charge the battery. Continue to charge the battery). When the equalizing charge current of the battery drops to the conversion condition of 10mA/Ah, the equalizing charge cannot be converted to the float charge program, and freewheeling equalizing charging must be performed (in a high temperature environment, the current of the equalizing charge in the freewheeling stage may still be rebound rises, the time for continuous flow and equalization is generally 4 to 10 hours). In addition, outdoor base stations have poor power supply conditions and frequent power outages, which will inevitably cause the switching power supply to overcharge the battery every time it is charged. It also accelerates the corrosion rate of the battery electrodes and the loss of water in the battery. The temperature inside the battery is extremely high, causing the battery casing to bulge.

　　3. The temperature sensing line of the gel battery compartment is not connected, causing the system to be unable to convert from equalizing charge to float charging when the temperature reaches 40°C. In a high-temperature environment, the failure of the temperature compensation function actually increases the total float voltage of the battery pack, which directly results in the battery's final charging current not being able to decrease. Instead, the charging current will increase exponentially, and will continue to affect the internal analysis of the battery. Gas and heat will be generated, thereby aggravating the electrolysis of the colloidal electrolyte water and causing the battery to bulge.

　　4. The battery ventilation conditions are poor. The design of the battery cabinet fully considers anti-theft safety, resulting in poor ventilation and natural heat dissipation capabilities of the battery pack. The temperature generated by the battery pack during charging cannot be diffused in time, which also has a certain impact on the bulging of the battery case.

　　Based on the above analysis, we have summarized solutions to the bulging of gel batteries during maintenance work. On the one hand, according to the characteristics of gel batteries, the following changes are made to the battery charging management software of the switching power supply:

　　1. In order to shorten the equalizing charging time and avoid battery bulging caused by overcharging, the equalizing and floating charging conversion conditions are reset. The original set current value of 10mA/Ah is changed as the equalizing charging conversion condition to the system when the current value drops to 20mA/Ah. That is, it automatically switches to float charging operation.

　　2. Connect the temperature sensor of the switching power supply to the battery cabinet so that the floating charge 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 float charging operation to avoid battery bulging caused by continuous high-current charging.

　　3. In order to prevent the battery from overcharging and shorten the equalizing charge protection time, the equalizing charging protection time is changed from 18 hours to 10 hours (the setting of the equalizing charging protection time is to prevent the battery from thermal runaway, when the average charging current cannot be reduced to the set average). When float charging converts the current value, the system is forced to switch to float charging within the specified time).

　　4. Extend the regular equalizing charging cycle to avoid over-frequency high-current equalizing charging. Change the original set value of the scheduled equalizing charging cycle from 100 days to 180 days.

　　5. Cancel the freewheeling equalizing charging function of the switching power supply to avoid battery swelling caused by overcharging.

　　The above modifications to the battery charging parameters are mainly to avoid overcharging the gel battery by the switching power supply while ensuring that the battery is fully charged.

　　On the other hand, in order to prevent poor exhaust caused by quality problems of the safety valve, attention should be paid to strengthening the inspection of the safety valve during daily inspections. At the same time, battery manufacturers are required to further improve the quality inspection and manufacturing process of the safety valve to ensure that the safety valve is in good condition. After reaching the opening valve value, the valve can be opened normally for exhaust.

　　Through the above processing, after a period of observation, the gel battery no longer has case bulging, and the operation is in normal condition.

　　To sum up, in the high temperature environment in the south, according to the characteristics of the gel battery, while ensuring that the battery is fully charged, the threshold current value and equalization protection time for equalizing charge to float charge should be set reasonably to avoid the occurrence of gel from overcharging the battery. Regarding the bulging problem of the battery case, it is necessary to protect the battery from over-temperature and strengthen the inspection of the safety valve. If problems are found, they must be rectified in time to improve the efficiency and service life of the gel battery. In this way, the advantages of gel batteries such as power saving and reducing lead and acid pollution to the environment can be fully utilized.

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