JPH0326775Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a power supply device used in a vehicle such as an automobile.

[Background Art] Vehicles such as automobiles are equipped with one storage battery, and the storage battery is used as a power source to start an engine and supply electricity to various loads such as lamps. Further, the on-vehicle storage battery is charged by an on-vehicle charging device while the engine is running.

[Problems that the invention aims to solve] However, in-vehicle storage batteries tend to discharge electricity when overloaded, such as when driving at night or in the rain, and when the vehicle is driven in a short period of time from starting the engine to stopping, or when the vehicle starts or stops. In driving conditions where frequent stops occur, the battery does not get charged much, so the capacity decreases without you even realizing it, which sometimes makes it impossible to start the engine.

[Means for Solving the Problems] The present invention provides a vehicle power supply device that can solve the above-mentioned problems such as the inability to start the engine, and for this purpose, the present invention provides a main storage battery and a backup storage battery. A current limiting resistor is arranged between the positive terminals of both storage batteries and connected in parallel, a switch is connected in parallel to the resistor, and a display device for displaying the voltage status of the backup battery is connected to the backup battery. The configuration is such that the capacity state of the main storage battery is detected based on the voltage transition of This makes it possible to start the engine, and also to monitor the capacity state of the main storage battery based on the voltage transition of the backup storage battery, so that appropriate measures can be easily taken when the capacity of the main storage battery decreases.

[Example] Hereinafter, the vehicle power supply device of the present invention will be described using an example shown in the drawings. In the figure, 1 is a main storage battery for engine starting and load power supply, 2 is a backup storage battery that is sufficiently small compared to the capacity of the main storage battery, and the main storage battery 1 and the backup storage battery 2 are connected in parallel. Reference numeral 3 denotes a current limiting resistor, which is inserted between the positive terminal of the main storage battery 1 and the positive terminal of the auxiliary storage battery 2. 4 is a switch connected in parallel to the resistor 3. 5 is a display device that displays the voltage state of the backup storage battery 2 connected in parallel to the backup storage battery 2, and includes a constant voltage element 6 and a resistor 7 for detecting the voltage of the backup storage battery 2;
It is comprised of a capacitor 8 that stores the detected voltage, a linear IC 10 that controls lighting of a plurality of LEDs 9 according to the voltage stored in the capacitor 8, and the like. 11 is an on-vehicle charging device, and the main storage battery 1 and the backup storage battery 2 are charged by the on-vehicle charging device. 12 is various on-vehicle loads.

In this embodiment of the present invention, when the charging voltage increases as the engine rotates and the main storage battery 1 is in a discharging state, charging current flows to the main storage battery 1 up to the drooping current of the charging device 11. In this case, since the current limiting resistor 3 is inserted in the reserve storage battery 2,
While the main storage battery 1 is charged with constant current and constant voltage, it is charged with trickle charge, that is, with a minute current. Also, in this case, since the charging current is small, the voltage of the reserve storage battery 2 is E (electromotive force) + △I (charging current) ×
R (current limiting resistance), the electromotive force factor is large, and if the reserve storage battery 2 is in a discharged state, the charging voltage is also low,
If the battery is fully charged, the charging voltage will also be high. This is because, in the case of trickle charging, since ΔI≒constant and R=constant, the terminal voltage of the reserve storage battery 2 changes depending on the level of the electromotive force. On the other hand, the charging voltage of the main storage battery 1 constantly changes depending on the engine speed, and even when this voltage is detected, there is no significant correlation with the capacity. The terminal voltage changes in proportion to the correlated electromotive force. Therefore, by detecting the terminal voltage of the backup storage battery 2, the capacity of the backup storage battery 2 can be detected. Next, the terminal voltage of the main storage battery 1 always fluctuates depending on the engine speed and load condition, but if the main storage battery 1 changes in the charging direction on average, the backup storage battery 2 will also enter the charging state after a predetermined time delay. and the opposite occurs during discharge. Further, if there is a difference in electromotive force between the main storage battery 1 and the backup storage battery 2 while the main storage battery 1 and the backup storage battery 2 are left unused, the electromotive forces of both storage batteries become equal over a long period of time. In this way, the backup storage battery 2 follows the main storage battery 1 with a certain delay so that it reaches the same capacity state. Further, the change in the terminal voltage of the reserve storage battery 2 is much smoother than the change in the voltage of the main storage battery 1. Therefore, by simply detecting changes in the terminal voltage of the backup battery 2, the capacity state of the main battery 1 can be detected quite accurately. That is, when the terminal voltage of the reserve storage battery 2 is 11.5V or less, the main storage battery 1 is in a discharged state, and when it is 12.6V or more, the capacity of the main storage battery 1 is normal, and the capacity can be displayed using an LED or a meter. For this reason, this embodiment is provided with a display device 5 that detects and displays the voltage state of the backup storage battery 2, and therefore, it is possible to know the capacity state of the main storage battery 1 by looking at the display on the display device 5. If the capacity of the main storage battery 1 is decreasing, appropriate measures can be taken. In addition, in the display device 5 in this embodiment, the number of LEDs 9 lit is changed sequentially depending on the level of the terminal voltage of the reserve storage battery 2. When the capacity is normal, the number of LEDs 9 lit is large, and when the capacity is reduced, the number of LEDs 9 lit is large. In this case, the LED 9 goes out one after another, indicating that the capacity of the main storage battery 1 is decreasing.

The above will be specifically explained as follows. The charging device 11 and the on-vehicle load 12 mounted on an automobile or the like have a very large value compared to the capacity of the storage battery. For this reason, the lamp turns on and off,
The power supply voltage always fluctuates significantly depending on the operation of the cooler, etc., driving conditions, etc. It is very difficult to judge the charging/discharging state of the storage battery based on the transition of this voltage. However, if a resistor of about 1 kilohm is placed between the main storage battery and the backup battery, even if the main storage battery is charged and discharged and the power supply voltage fluctuates significantly, the voltage at the backup storage battery terminal will only change slightly. If the main storage battery is in the direction of charging as an integral value, the backup storage battery will also be gradually moving in the direction of charging, and by detecting the terminal voltage, it can be determined in which direction the main storage battery is moving. If there were no current limiting resistor, the voltage of the backup battery would fluctuate in synchronization with the main battery, making it difficult to configure a capacity meter. Also, of course, since a current limiting resistor is installed, there will be a difference in capacity between the main storage battery and the backup battery, but when the current limiting resistor is 500 ohm, it will take 10 minutes, and when the current limiting resistor is 1 kilo ohm, it will take 30 minutes. It was confirmed that this amount is acceptable even if it is configured as a capacitance meter. In addition, the capacity meter configured by detecting the voltage of the backup storage battery has a smooth and easy-to-read display, improving its versatility as a meter.

Next, the function as an auxiliary power source will be explained.
Even when the main storage battery 1 is in a discharged state, the backup storage battery 2 is in a discharged state with a delay of 1 to 2 hours because the current limiting resistor 3 is present. When the main storage battery 1 is in a discharged state and left in this state, the surface of the electrode plate of the main storage battery 1 is activated by a minute current flowing from the reserve storage battery 2 to the main storage battery 1 while the main storage battery 1 is left unused. The engine will not be unable to start. Further, if the engine cannot be started due to a decrease in the capacity of the main storage battery 1 after being left unused for a short period of time, the switch 4 can be closed and the engine can be started using the backup storage battery 2. Furthermore, if the capacity of the backup storage battery 2 decreases while driving, if the load 12 is reduced and the switch 4 is closed, both the main storage battery 1 and the backup storage battery 2 can be connected to the charging device 1.
1, the main storage battery 1 can be charged rapidly, and the problem of inability to start due to a decrease in the capacity of the main storage battery 1 can be completely eliminated.
Note that in normal use, the switch 4 is in an open state.

In this way, in the embodiment of the present invention, the capacity state of the main storage battery 1 can be known by looking at the display on the display device 5, so that when the capacity of the main storage battery 1 is decreasing, appropriate measures can be taken. When the capacity of the main storage battery 1 has decreased, the main storage battery 1 can be charged by the backup storage battery 2, or an accident in which the engine cannot be started due to a decrease in the capacity of the main storage battery 1 can be prevented by using the backup storage battery 2. Furthermore, the backup storage battery 2 does not constantly charge and discharge rapidly like the main storage battery 1, but on the other hand, it is trickle charged while driving and maintains an optimal state of charge, so it has a longer lifespan than the main storage battery 1, and the power supply The reliability of the device as a whole can be improved, and it can fully fulfill its role as an auxiliary power source.

[Effects of the invention] As described above, the vehicle power supply system of the present invention can prevent accidents such as the inability to start the engine, and furthermore, since it is possible to know the capacity status of the main storage battery, it is easy to use appropriate power supply when the capacity of the main storage battery 1 decreases. It has excellent advantages such as the ability to take appropriate measures.

[Brief explanation of the drawing]

The figure is a circuit diagram showing an embodiment of the vehicle power supply device of the present invention. 1... Main storage battery, 2... Reserve storage battery, 3... Current limiting resistor, 4... Switch, 5... Display device, 11
...In-vehicle charging device, 12...Various in-vehicle loads.

Claims (1)

[Scope of utility model registration request] The main storage battery and the backup storage battery are connected in parallel with a current-limiting resistor placed between the positive terminals of both batteries, a switch is connected in parallel to the resistor, and the voltage status of the backup storage battery is displayed on the backup battery. A vehicle power supply device that is configured to connect a display device and detect the capacity state of a main storage battery based on the voltage transition of a backup storage battery.