JP4325021B2 - Lead storage battery charge control method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to charge control for lead acid batteries, and more particularly to a charge control method for lead acid batteries when the remaining capacity is used in an intermediate state.
[0002]
[Prior art]
One of the major uses of lead-acid batteries is for automobiles. This is used for auxiliary equipment such as a power source for turning the cell motor when the engine is started, a power source for an audio device and an air conditioner in a vehicle, and a power source for various assist devices such as a power steering and a brake. In recent years, in addition to these, use as a motor power source of a hybrid electric vehicle equipped with a motor as an assist for an internal combustion engine (engine) has been studied.
[0003]
When a lead storage battery is used as a power source for a motor, the amount of electricity used is so large that it cannot be compared with a lead storage battery for an auxiliary machine. When used in such applications, it is necessary to positively use regenerative charging that increases the battery capacity while storing energy during braking as an electric quantity. As a feature of regenerative charging, since the energy at the time of braking is stored as an electric quantity, the electric power generation amount and the electric power generation time are random, and this cannot be used as it is for controlling charging. However, the amount of power generation is large, and if this can be charged to the lead storage battery, it becomes possible to maintain an appropriate remaining capacity value, and more assistance can be achieved.
[0004]
In order to efficiently accept this regenerative charge, for example, as in JP-A-8-308018, power generation is normally controlled at a target value of 13 V close to the battery open terminal voltage, but the power generation rate is reduced to 90 to 99%. Then, this target value is 14.5V, and it is proposed that the battery is quickly charged and then restored to the original 13V when the power generation rate becomes 70% or less.
[0005]
[Problems to be solved by the invention]
However, when the battery is continuously charged with a low discharge frequency, the battery is likely to be overcharged and its life is shortened. Further, as described above, regenerative charging cannot be fully utilized.
[0006]
On the other hand, due to the characteristics of lead-acid batteries, the range of available remaining capacity is a value within a certain range. For example, when the battery remaining capacity (SOC) is about 50%, the specified voltage cannot be taken or used as it is. If you continue, problems such as shortening the service life will occur.
[0007]
This invention solves the said subject, and aims at providing the charging method which can suppress the lifetime reduction of a lead acid battery.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a first step of continuously controlling the voltage of the lead storage battery to a constant voltage lower than the open circuit voltage in the fully charged state of the lead storage battery, and the lead storage battery within a predetermined time. the high constant voltage than the open circuit voltage in the fully charged state, characterized in that have a second step of charging to fully charge the lead-acid battery. By adopting such a configuration, the lead-acid battery can prevent the deterioration of the life characteristics while continuing to generate a specified voltage.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
[0010]
FIG. 1 is a conceptual diagram of a circuit including a lead-acid battery mounted on an automobile showing an example of this embodiment, a generator attached to an engine, and a load such as a cell starter. FIG. It is a timing chart which shows the voltage and electric current when one form is implemented.
[0011]
First, a large discharge is performed to the cell starter (load 1) in order to start the engine when starting. At this time, the voltage also drops greatly, but is immediately charged to V1 by the generator 2, and then constant voltage charging is performed at V1 only for time T1. The lead storage battery 1 is discharged by various auxiliary machines (load 1) during the time T2, but is controlled to the constant voltage V2 by the generator 2, and is constant and set by the constant voltage V2. It is kept above the SOC. This constant voltage control is set lower than the open circuit voltage of the lead storage battery 3 used, and the average SOC can be controlled by this voltage.
[0012]
Next, when a certain time has elapsed, the charging voltage from the generator 2 is increased, and the lead storage battery 3 is brought into a fully charged state. Thereafter, the constant voltage V2 set lower than the open circuit voltage of the lead storage battery 3 is again maintained at a constant voltage, that is, a constant SOC. Thus, by fully charging every fixed time, it is possible to prevent the battery life from being reduced due to insufficient charging or the like. These charging voltages are controlled by the regulator 4.
[0013]
FIG. 3 is a flowchart showing charging control of a lead storage battery mounted on an automobile. Insert the ignition key and start the system. First, when the cell starter is turned on to start the engine, charging is started at the voltage V1. When the battery voltage becomes equal to V1 by this constant voltage charging, the battery is further charged for a time T1.
[0014]
From the time when this charging is completed , the lead storage battery 1 is controlled by the voltage V2. During this time, discharge is performed by a load such as a headlight, an air conditioner, an audio, and a steering assist. However, since the generator is charged with a constant voltage, the storage battery does not fall below that voltage. When VB = V2, electricity is supplied from the generator to the load.
[0015]
When the time during which the lead storage battery 1 is controlled to the voltage V2 reaches a set value T2, the battery is charged at a voltage V4 that is higher than the open circuit voltage in the fully charged state . By performing this charging, deterioration of the life characteristics can be prevented without leaving the lead storage battery in a discharged state. The battery is further charged with the voltage V4 for a time T3 from when VB = V4. When this is completed, the charging voltage V2 is restored, and the time T2 is counted by a timer.
[0016]
On the other hand, when the voltage V3 higher than the voltage V4 is entered as the regenerative power during the control with the constant voltage V2, and it becomes VB = V3 due to the regenerative power, it is determined that the full charge has been performed and the time T2 is determined. Set again. If VB does not rise to V3 even when regenerative power is turned on, the time T2 count is continued. As a result, charging and discharging can be continued without wasting regenerative power and while maintaining a good battery state.
[0017]
In addition, in this Embodiment, although the lead acid battery uses the single battery, if it is set as an assembled battery according to purposes, such as a high voltage and a high output, there can exist the effect of this invention further.
[0018]
【Example】
A life test was performed using the present embodiment using the above-described charging control method and a comparative example in which charging with the voltage V4 was not performed. The battery was a 12V10Ah lead acid battery, and the environmental temperature was 50 ° C. V1 is set to 14.0V, V3 is set to 15.0V, and V4 is set to 14.5V. V2 is set to 12.8V when the lower limit of the SOC is 80%, and 12.4V when the lower limit of the SOC is 60%. did. The cell starter was discharged at 100 A for 2 seconds, and the timer was set to T1 for 0.5 minutes, T2 for 3 minutes, and T3 for 1 minute.
[0019]
The test results conducted under such conditions are shown in FIG. From this figure, it was found that this example can clearly suppress the deterioration of the life characteristics.
[0020]
【The invention's effect】
As described in detail above, according to the present invention, by being charged with a constant voltage set lower than the open circuit voltage of the lead storage battery that is always used, and being fully charged every certain time, Insufficient charging can be resolved, and an unexpected stop of the device can be prevented, and a decrease in the life of the lead-acid battery can be prevented.
[Brief description of the drawings]
FIG. 1 is a schematic circuit diagram according to an embodiment of the present invention. FIG. 2 is a diagram showing timing of battery voltage, current, and remaining capacity according to an embodiment of the present invention. Flow diagram [Fig. 4] Diagram showing results of life test [Explanation of symbols]
1 Load 2 Generator 3 Lead acid battery 4 Regulator

Claims (2)

A first step of continuously controlling the voltage of the lead-acid battery to a constant voltage lower than the open-circuit voltage in the fully charged state of the lead-acid battery; and a constant higher than the open-circuit voltage in the fully charged state of the lead-acid battery within a certain time A charge control method for a lead storage battery, comprising a second step of charging the lead storage battery to a full charge with a voltage . The lead storage battery charge control method according to claim 1, wherein the lead storage battery is an assembled battery in which a plurality of single cells are connected in series.

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