1, Battery charging
In theory, the smaller the charging current, the better. Because the current is small, the finer the crystals formed by the reaction, the more complete the reaction, and the more electricity that can be stored.
Three-stage charging method:
The first stage is fast charging, constant current charging stage, charging the battery with the maximum output current of the charger. If it is a solar controller, it is working at the maximum power point of MPPT. The charging time depends on the battery capacity and the battery status when charging starts. . In the second stage, the charging process is constant, the charging voltage of the charger is kept constant, the charging capacity continues to increase, the battery voltage rises slowly, and the charging current decreases. In the third stage floating charging mode, the battery is basically full and the charging current drops below The floating charge converts the current, and the charging voltage is lowered to the floating charging voltage.
2, Working environment temperature
Excessive ambient temperature has a large impact on the service life of valve-controlled batteries. When the temperature rises, the plate corrosion of the battery will increase, and more water will be consumed, thereby shortening the battery life. Valve-controlled power storage requires certain temperatures during use. When a typical valve-controlled battery is above 25 ° C, the battery life is reduced by half for every 6 to 9 ° C increase. Therefore, the float voltage should be compensated according to the temperature, which is generally 2 to 4 mV/°C, and many existing chargers do not have this function. In order to achieve the optimal service life of the valve-controlled battery, the use environment under constant temperature should be created as much as possible while maintaining good ventilation and heat dissipation conditions of the battery. Specifically, the room in which the battery is placed should have air conditioning equipment. The battery should be placed with proper spacing to improve the heat exchange between the battery and the environmental medium. A gap of not less than 15 mm is maintained between the batteries, and a "ventilation passage" having a spacing of not less than 150 mm between the battery and the upper partition is used to lower the temperature rise.
3, Battery discharge depth
During battery use, the percentage of the battery's discharged capacity as a percentage of its rated capacity is called the depth of discharge (DOD). The depth of discharge has a deep relationship with the battery life. The deeper the depth of discharge, the shorter the charging life. Therefore, deep discharge should be avoided when using. The discharge depth of the battery is about 10% to 30% for shallow cycle discharge; the discharge depth is about 40% to 70% for medium cycle discharge; the discharge depth is about 80% to 90% for deep cycle discharge.
In general, the deeper the daily discharge depth of the battery for long-term operation, the shorter the battery life, the shallower the discharge depth, and the longer the battery life. Shallow cycle discharge helps to extend battery life. The shallow cycle of the battery has two distinct advantages: first, the battery generally has a long cycle life; second, the battery often maintains more spare ampere-hour capacity, so that the photovoltaic system's power supply guarantee rate is higher. According to the actual operating experience, the moderate discharge depth is 60% to 70%.
Over-discharge mainly occurs after the AC power supply is cut off, and the battery supplies power to the load for a long time. When the battery is over-discharged, it causes "sulfation" at the cathode of the battery. Since lead sulfate is an insulator, its formation will have a great negative impact on the charge and discharge performance of the battery. The more sulfate formed on the cathode, the greater the internal resistance of the battery, the worse the charge and discharge performance of the battery, and the shorter the service life of the battery. The lead sulfate formed under the condition of small current discharge is very difficult to be redoxed. If the lead sulfate crystal is not cleaned for a long time, it will inevitably affect the capacity and service life of the battery.
