JPH08287955A - Method of charging sealed lead-acid battery - Google Patents

Abstract

PURPOSE: To improve the life of the above battery by adopting a specified charge method, in float charging, or intermittent float charging where trickle charging or charging suspension are performed alternately, or intermittent trickle charging. CONSTITUTION: Charging is performed at a specified constant voltage within the voltage range of 2.2-2.3V/cell, and at the point of time when the current drops to the specified voltage or lower, the charging is suspended, and the suspension time is decided by the temperature of a battery, and the upper limit is set to thirty days or less. Or, in place of deciding the suspension time by the battery temperature, it is set to the point of time when the open voltage of the battery during suspension has dropped to the specified voltage, the upper limit of the suspension time is made thirty days or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for charging a sealed lead battery.

[0002]

2. Description of the Related Art There are usually two types of methods for charging a sealed lead-acid battery as a backup power source. One is to constantly supply the electric power to the load while charging the battery, and the momentary large current is applied to the load. The load is shared by the charger and the battery when the current flows to the load, and when the commercial power supply fails, it is a float charging method that supplies power from the battery to the load without interruption. This is a trickle charging method in which the battery is connected to the load to supply power when the commercial power supply fails, only charging that maintains a fully charged state.

The life of lead-acid batteries is usually determined by the corrosion of the positive plate grid. The positive electrode plate grid is always in a corroded state because it is constantly in contact with lead dioxide, which is a positive electrode active material that gives a high potential in the electrolytic solution. This tendency to corrode is further enhanced when the battery is in a charged state because the charging overvoltage is further added in addition to the potential of lead dioxide.

The positive electrode plate grid has both a function as a current collector and a function of holding an active material. When the grid is corroded, the electrical resistance is increased or the mechanical strength is decreased, these functions are deteriorated, the capacity is decreased, and the life is reached. Therefore, how to minimize the corrosion of the positive plate grid is the key to prolonging battery life.

[0005]

Charging is an essential operation for supplying sufficient electric power in an emergency, but it accelerates corrosion of the positive plate grid and shortens battery life. Against this background, there is strong hope for the development of a charging method that strikes a good balance between the two contradictory objectives of maintaining the state of charge and extending the life of the battery. In the conventional floating charging method, the battery is always charged except for discharging in an emergency, so that the corrosion of the positive electrode plate grid progresses in proportion to the charging time, and thus the charging time is the service life of the battery. Therefore, it is difficult to further extend the battery life limited by the positive electrode grid corrosion.

[0006]

According to the charging method of the present invention, in the floating charging use of a sealed lead battery, the cumulative charging time is reduced by alternately repeating the charging time and the rest time instead of the conventional charging method. It extends the battery life. In this method, the battery is charged at a predetermined constant voltage within the range of 2.2 V to 2.3 V / cell, the charging is stopped when the charging current drops below a predetermined value, and the rest time is determined by the temperature. Further, instead of determining the rest time according to the temperature, the start of charging after the rest is set to the time when the open circuit voltage of the battery drops below a predetermined voltage.

[0007]

【Example】

(Example 1) In a standby power supply system in which 56 sealed lead batteries having 2 V cells and a capacity of 200 AH (10 HR) were connected in series, the discharged batteries were insufficiently charged at a constant voltage of less than 2.2 V / cell. Charging was performed at a constant voltage of 0.2 V / cell, and the charging was stopped when the current decreased to 0.1 A as the charging proceeded. The rest time t (h) was based on the temperature T (° C) measured by a thermistor type thermometer attached to the battery, and the value calculated by the following equation was input to the control system.

T = 360 × (20 / T) ^{2 Further} , if the rest time calculated by the above formula exceeds 30 days, irreversible lead sulfate accumulates in the electrode plate and causes a capacity decrease, so the upper limit is 30. Until the day.

Comparing the decrease in capacity of a battery which has been subjected to this charging method for two years with that of the same type of battery used in the conventional charging method, the decrease in capacity of the battery used by the charging method of the present invention is It was 84% of that of the battery used in the charging method of. (Embodiment 2) With respect to the same standby power supply system as in Embodiment 1, charging after discharging is performed at a constant voltage of 2.3 V / cell because the corrosion of the grid becomes large at a constant voltage exceeding 2.3 V / cell. did. All the conditions other than the charging voltage were the same as in Example 1 and tested.

Comparing the decrease in battery capacity of a battery which has been subjected to this charging method for two years with that of the same type of battery used in the conventional charging method, the decrease in capacity of the battery used by the charging method of the present invention is , 88% of that of the battery used in the conventional charging method. (Embodiment 3) A standby power supply system in which 56 sealed lead-acid batteries having a capacity of 200 AH (10 HR) of 2 V are connected in series. The discharged battery is 2.2 V / cell because the battery is insufficiently charged at less than 2.2 V / cell. It was charged at a constant voltage. Charging was stopped when the charging current dropped to 0.1 A. The start of charging was calculated by the following equation showing the relationship between the electrolytic solution specific gravity value G detected by the specific gravity sensor attached to the battery and the open circuit voltage E (V) of the battery at that specific gravity, and input to the control circuit in the system.

E = 0.92G + 0.95 In this test, charging was started when the open circuit voltage fell below 2.120V. Further, when the rest time for reaching the open circuit voltage calculated by this formula exceeds 30 days, irreversible lead sulfate accumulated in the electrode plate and caused a capacity decrease, so the upper limit was set to 30 days. If the open circuit voltage did not drop to 2.120V after 30 days, charging was automatically started. Comparing the decrease in battery capacity of a battery that has been subjected to this charging method for two years with that of the same type of battery used in the conventional charging method, the decrease in capacity of the battery used by the charging method of the present invention is It was 82% of that by method. (Embodiment 4) With respect to the same standby power supply system as in Embodiment 3, at constant voltage after discharge exceeding 2.3 V / cell, since grid corrosion is large, charging is performed at constant voltage of 2.3 V / cell. I went. The test was performed in the same manner as in Example 1 except for the charging voltage.

Comparing the decrease in battery capacity of a battery which has been subjected to this charging method for two years with that of the same type of battery used in the conventional charging method, the decrease in capacity of the battery used by the charging method of the present invention is It was 87% of that of the conventional charging method.

[0013]

EFFECTS OF THE INVENTION In intermittent float charging or intermittent trickle charging, the charging time and the rest time are repeated, so that the time spent in the charging state becomes shorter than that in the conventional charging method, and therefore, the overvoltage of the charging loads the battery. This shortens the exposure time, reduces the corrosion of the positive electrode plate grid, and extends the battery life.

Claims (2)

[Claims] 1. In the use of intermittent float charging or intermittent trickle charging in which float charging or trickle charging and charging suspension are alternately performed, charging is performed at a predetermined constant voltage within a range of 2.2 to 2.3 V / cell. , A method for charging a sealed lead-acid battery, characterized in that charging is stopped when the charging current drops below a predetermined value, the charging suspension time is determined by the battery temperature, and the upper limit is set to 30 days. 2. In the use of intermittent float charging or intermittent trickle charging in which float charging or trickle charging and charging suspension are alternately performed, charging is performed at a predetermined constant voltage within a range of 2.2 to 2.3 V / cell. , Charging is stopped when the charging current drops below a predetermined value, and the charging pause time is set to the time when the open circuit voltage of the battery during charging pause falls to a predetermined voltage and the upper limit of the pause time is set to 30 days. Floating charging method for sealed lead-acid battery, characterized by: