JPH05273316A - Meter for measuring remaining charge of nicd battery - Google Patents

Abstract

PURPOSE:To obtain a meter for accurately indicating the remaining charge of an NiCd battery in terms of the period of time for which a load can run on the battery. CONSTITUTION:A current quantity detecting section 2 detects a charged and discharged currents and, at the same time obtains the information about the flowing time of the currents by means of a clock circuit 3. A residual charge calculating section 4 calculates the residual charge of a NiCd battery 1 from the output of the section 2 and stores the results in a storing section 5. A remaining operating time calculating section 7 reads out the contents of the section 5 and calculates the period of time for which a load can run, on the basis of the operating current of the load and the discharge and temperature characteristics of the battery 1. A remaining operating time displaying section 19 displays the results in hours and minutes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a NiCd (nickel cadmium) battery capacity fuel gauge used in terminals such as mobile phones, and more specifically, to accurately determine the NiCd battery capacity from the battery capacity and the amount of current used. The present invention relates to a fuel gauge for a NiCd battery that can be measured and displayed on the screen.

[0002]

2. Description of the Related Art Conventionally, the display method of the remaining amount of a NiCd battery is almost always displayed in two steps or three steps. For example, in the case of three levels, the number of 3 to 1 is often used or the remaining amount is often displayed using three bar graphs.
Since the above-mentioned display is made by detecting the voltage of the NiCd battery, the display is not accurately divided into three equal parts.

[0003]

FIG. 2 is a graph showing the discharge characteristics of a NiCd battery. The NiCd battery exhibits a high voltage value until just before the storage of electricity is stopped, and has stable discharge characteristics with a very small fluctuation range for a long time. However, since the fluctuation range is extremely small, it is difficult to display in stages by voltage. For example, in the case of three-stage display, the display is as shown in FIG. As can be understood from FIG. 2, even if a considerable amount of voltage is consumed, "3" is shown, and when it becomes "2" or "1", there is almost no remaining amount. Also, unless the user is notified in advance in the instruction manual that the display is made in this way, if the user displays "2", the remaining amount is half of the full charge. There is a risk of misunderstanding. Therefore, it is meaningless to display four, five, or more stages from this discharge characteristic.

By the way, in the case of a cellular phone or the like using a NiCd battery, the cellular phone carrier must know in advance exactly how many hours a phone call can be and how many hours can be waited.
There is a fear of disconnection during a call. Therefore, what is required is not a rough guideline but can display exactly how many hours and minutes can be used. The present invention has been made in view of the above circumstances, and an object thereof is NiCd.
An object of the present invention is to provide a NiCd battery fuel gauge that can accurately display the remaining battery power by converting it to the usage time of the terminal.

[0005]

In order to achieve the above object, a fuel gauge for a NiCd battery according to the present invention detects the charge / discharge current amount from the charge / discharge current to the NiCd battery and the time during which the current flows. A current amount detection unit, a remaining battery capacity calculation unit that calculates the remaining battery capacity of the NiCd battery from the output of the current amount detection unit, and a remaining battery capacity that stores the remaining battery capacity that is the calculation result of the remaining battery capacity calculation unit. A storage unit, a characteristic storage unit that stores the discharge characteristic and temperature characteristic of the NiCd battery, a temperature sensor that senses the ambient temperature, and an N in the characteristic storage unit that detects the ambient temperature by the temperature sensor.
A remaining operating time calculation unit for calculating the remaining operating time of the load from the remaining battery capacity read from the remaining battery capacity storage unit based on the current consumption of the load with reference to the discharge characteristics and temperature characteristics of the iCd battery, and the remaining operating time calculation And a display unit that displays the remaining operating time calculated by the unit.

[0006]

According to the above construction, the operating time of the load (terminal) corresponding to the remaining amount of the NiCd battery can be accurately displayed, and the terminal is no longer used with fear of when it will be unusable.

[0007]

The present invention will be described in more detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a fuel gauge for a NiCd battery according to the present invention. The battery capacity of a NiCd battery is represented by the product of the time from when the battery starts to be discharged to when the discharge end voltage is reached and the discharge current value. Ah, mAh
Expressed in units of. Generally, a rated current is set for each model, but this value is based on the capacity when discharging a current of 0.2c (5 hour rate). At present, it is impossible to directly measure how much Ah remains in a battery when used to some extent.

Therefore, the present invention is provided with a current amount detector 2 for measuring the amount of current charged in the NiCd battery 1 and the amount of current discharged from the battery. The current amount detector 2 always detects the charge / discharge current to the battery 1 and receives the clock output from the clock circuit 3 to detect the time during which the current is flowing. The remaining battery capacity detection unit 4 calculates the remaining battery capacity from the discharging or charging current and the flowing time. Then, the remaining battery capacity is stored in the storage unit 5.
A reset button 6 is provided to clear the contents of the storage unit 5. This reset button 6 is Ni
It is necessary to press the Cd battery 1 when the Cd battery 1 is completely discharged, and set the storage unit 5 in advance so that the storage unit 5 has 0 Ah.

The remaining operating time calculation unit 7 calculates from the remaining battery capacity read from the storage unit 5 how long the load, that is, the terminal, can operate. At this time, the current consumed by the terminal during operation is known. However, the capacity actually obtained by discharging is not always constant, and is greatly affected by the discharge current and the ambient temperature. Therefore, the characteristic storage unit 8 stores the discharge characteristic and the temperature characteristic for each model. In addition, the remaining operating time calculation unit 7 is provided with a temperature sensing unit (temperature sensor) 9 that constantly measures the ambient temperature in order to use the temperature characteristic in the characteristic storage unit 8. The remaining operating time calculation unit 7 measures the temperature, reads the discharge characteristic of the temperature characteristic corresponding to the temperature from the characteristic storage unit 8, and calculates the remaining time based on the value of the current flowing through the terminal. Remaining time display section 10
Displays the calculated remaining time in hours and minutes.

[0010]

As described above, according to the present invention, the NiCd is used.
It is configured to detect the charge and discharge flow of the battery, calculate the remaining battery capacity according to the time during which the current is flowing, and calculate and display the remaining operation time according to the operating current, discharge characteristics and temperature characteristics of the load. ing. Therefore, there is an effect that it is possible to accurately know the available remaining time of a terminal such as a mobile phone, and to eliminate the anxiety that the remaining battery level is unclear and the battery becomes unusable.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a fuel gauge for a NiCd battery according to the present invention.

FIG. 2 is a graph showing discharge characteristics of a NiCd battery.

FIG. 3 is a graph showing discharge characteristics for explaining a usage time of a NiCd battery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... NiCd battery 2 ... Current amount detection part 3 ... Clock circuit 4 ... Remaining battery capacity calculation part 5 ... Storage part 6 ... Reset button 7 ... Remaining operating time calculation part 8 ... Discharge characteristic temperature characteristic storage part 9 ... Temperature sensing part 10 ... Remaining operating time display

Claims (1)

[Claims] 1. A current amount detection unit for detecting a charge / discharge current for a NiCd battery and a time during which the current is flowing, and a remaining battery capacity of the NiCd battery from an output of the current amount detection unit. A remaining battery capacity calculation unit for calculating, a remaining battery capacity storage unit for storing the remaining battery capacity which is the calculation result of the remaining battery capacity calculation unit, a characteristic storage unit for storing the discharge characteristic and the temperature characteristic of the NiCd battery, A temperature sensor that senses the ambient temperature, and the ambient temperature is detected by the temperature sensor and the discharge characteristics and temperature characteristics of the NiCd battery in the characteristic storage unit are referred to read from the remaining battery capacity storage unit from the current consumption of the load. It is composed of a remaining operation time calculation unit that calculates the remaining operation time of the load from the remaining battery capacity, and a display unit that displays the remaining operation time calculated by the remaining operation time calculation unit. N characterized by
Fuel gauge of iCd battery.