초록 ▼

A device and method for determining the state of charge of a battery includes a microprocessor-controlled arithmetic unit connected in parallel to the terminal voltage of the battery. The arithmetic unit is selectively connectable with an ohmic reference resistance placed in parallel with a load res

A device and method for determining the state of charge of a battery includes a microprocessor-controlled arithmetic unit connected in parallel to the terminal voltage of the battery. The arithmetic unit is selectively connectable with an ohmic reference resistance placed in parallel with a load resistance which is arranged in series with the battery, and with a capacitor chargeable or dischargeable via the arithmetic unit. The arithmetic unit is further capable of acquiring a value of the voltage drop across the capacitor. The arithmetic unit is operable in a first operating state in which it is disconnected from the reference resistance, and a second operating state in which the arithmetic unit is connected with the resistance. After the capacitor is charged to the terminal voltage of the battery, it is allowed to discharge. With the arithmetic unit in the first operating state, a first point in time marked by the voltage across the capacitor reaching a first threshold value is registered. In the second operating state, with the reference resistor connected to the arithmetic unit, a second point in time indicated by the voltage across the capacitor reaching a second threshold value is registered. The time difference between reaching the two threshold values represents a measured value proportional to the internal resistance, which in turn directly relates to the residual capacity of the battery.

대표청구항 ▼

[ What is claimed is:] [1.] A device for determining a state of charge of a battery, comprising:a microprocessor-controlled arithmetic unit connected across the battery such that a terminal voltage of the battery is measurable;an ohmic reference resistance selectively connectable to said arithmetic

[ What is claimed is:] [1.] A device for determining a state of charge of a battery, comprising:a microprocessor-controlled arithmetic unit connected across the battery such that a terminal voltage of the battery is measurable;an ohmic reference resistance selectively connectable to said arithmetic unit, said arithmetic unit being switchable between a first operating state in which the reference resistance is disconnected from said arithmetic unit, and a second operating state in which the reference resistance is connected across the battery via the arithmetic unit;a capacitance connectable to said arithmetic unit and being alternately chargeable and dischargeable via the arithmetic unit, said arithmetic unit being capable of measuring and evaluating a voltage drop across the capacitance, said arithmetic unit, while in said first operating state registering a first point in time corresponding to the voltage drop reaching a first threshold value resulting from a discharge time applicable to the capacitance, and while in the second operating state registering a second point in time corresponding to said voltage drop reaching a second threshold value, the arithmetic unit measuring the time difference between points in time of reaching the first and second threshold values, said second threshold value being based upon the terminal voltage while said arithmetic unit is in said second operating state, whereby said time difference represents a measured value proportional to an internal resistance of the battery.