With the rapid development of the communication industry in recent years, facilities such as trunk fiber optic cables, microwave unmanned stations and mobile base stations have been built successively, and a large quantity of storage battery packs are used in these facilities. Storage battery has high cost and accounts for a large proportion of the investment, so the storage battery should be correctly used and reasonably maintained to avoid battery capacity, service life and number of times of charge/discharge from being incapable of reaching the nominal criteria, thus it is crucial to perform scientific charging management for the storage battery.
Usually, the storage battery needs to be recharged after it is used, to recover its battery capacity, in order to supply power when the commercial power is powered off accidentally. The charging of the storage battery is realized by a switching power supply, therefore, whether the charging management method for the switching power supply is good or not will directly influence the battery capacity and service life of the storage battery.
There are two modes for the switching power supply to charge the storage battery. One mode is an floating charging mode wherein the charging voltage is 2.23V-2.25V per one cell, for some storage batteries used for communication, and a charging voltage is applied on the storage battery which has been charged to generate a tiny charging current, the function thereof is to compensate the power consumption caused by the self-discharge of the storage battery, so that the storage battery can stably keep its battery capacity. The other charging mode is an equalizing charging mode, in which the charging voltage is 2.35V per one cell for some storage batteries used for communication, and the rapid charging is performed on the discharged storage battery in order to supplement power to the discharged storage battery in time. In order not to damage the service life of the storage battery, the equalizing charging is usually needed in the following cases: for example, when the installation of the new storage battery system is completed, it needs to use the equalizing charging mode to charge the storage battery packs; if being not used for a period of time, it needs to use the equalizing charging mode to charge the storage battery; when charging in the floating charging mode for a period of time, it needs to use the equalizing charging mode to charge the storage battery; after being deeply discharged, it needs to use the equalizing charging mode to charge the storage battery.
At present, in the charging management for the storage battery, there are many modes to equalizing charge the storage battery, mainly comprising: constant-current charging method, two-stage charging method and constant-voltage charging method. The constant-current charging method means that the charging current is kept at a constant value during the charging of the storage battery, and has the disadvantage as follows: at the late stage of charging, the charging current is mostly used for electrolyzing water and a large amount of hydrogen and oxygen is generated, and only a small part of these gases can be chemically recombined to water, and as a result, the interior pressure of the storage battery is increased, such that the gas exhaust valve is open, which makes the battery loses water. The constant-voltage charging method means that the charging voltage is kept at a constant value during the charging of the storage battery, and has the disadvantage as follows: at the early stage of charging, the charging current is very large, and as a result, the lead sulfate attached to the battery plate is easy to fall off, which will form irreversible vulcanization, which greatly influences the battery capacity and the service life of the storage battery. In the worse situation, excessive charging current can easily make the pole plate of the battery bent and further make the battery scrapped. The two-stage charging method is a quick charging method combining the constant-current charging method and the constant-voltage charging method together. In this method, a constant current is first used to charge the storage battery to have the storage battery being at the predetermined voltage value, and then the constant-voltage charging method is used to complete the rest charging of the storage battery. The disadvantage of this method is that, the constant current first used is also relatively large, which also can easily make the lead sulfate attached to the battery plate fall off, forming irreversible vulcanization and influencing the service life. In addition, during the charging process using these methods, with the charging progresses, particularly in a case of charging with a large current, the temperature of the storage battery rises gradually, and the rising temperature will aggravate the corrosion of the pole plate of the battery and consume water in the storage battery, and as a result, the service life of the storage battery is shortened, the battery capacity is decreased, and even the storage battery is damaged.
Therefore, how to realize the charging of the storage battery quickly and safely becomes a problem to be solved.