Circuit for measuring and displaying the remaining capacity of an accumulator.

p0001The invention is based on a circuit arrangement according to the preamble of claim 1.

p0002It is such a circuit arrangement is known (Panasonic Tentative Specifications SKC 025, 06.11.1990), in which by an electronic measuring circuit by current and time measurement, the instantaneously available capacity of a housed in a cartridge battery is measured. The measured value is displayed on a provided on the accumulator display cassette. The known circuit arrangement has the disadvantage that the measured capacitance value can be read only on the display of the accumulator cartridge as other electrical functions of an electrical appliance connected to the accumulator cassette are displayed on a display of the device.

p0003The invention has the object of providing a circuit arrangement according to the preamble of claim 1 such that the display of the currently available capacity of the battery is carried out on a display of the electronic device.

p0004This object is achieved in a circuit arrangement according to the preamble of claim 1 by the features specified in the characterizing part of this claim. This has the advantage that the display of available battery capacity on the same display is performed as the display of other electrical functions or settings of the electrical appliance. Another important advantage is obtained if it is provided for the reciprocal transmission of data signals between electronic measuring circuit and the microprocessor circuitry of the device, only one additional line. Then, the battery cartridge need only have three terminals, namely a first terminal for the positive pole of the DC power supply, a second terminal for the negative terminal and a third terminal for the mutual transmission of the signals.

p0005Embodiments of the invention a number of figures are illustrated in the drawing from and will be described in more detail below. Show it<dl id="dl0001"><dt>Fig. 1</dt><dd>a circuit diagram of the circuit arrangement,</dd><dt>FIG. 2</dt><dd>a circuit diagram of the measuring circuit, which is complemented by a display,</dd><dt>Fig. 3</dt><dd>a diagram of a battery cartridge having supplemented by a charging circuit measuring circuit and</dd><dt>Fig. 4</dt><dd>the timing of the data transmission.</dd></dl>

p0006In Fig. 1, 10 designates an accumulator cartridge comprising a, for example, multi-cell battery 11 and an electronic sensing circuit 12. The electronic measuring circuit has three terminals 13, 14, 15, with those of three other terminals 16, 17 and 18 of an electrical device 20 which is for example a radio unit correspond. The electrical device 20 includes, connected to the further terminals 16 to 18 Devices circuit 21 to the microprocessor circuit 22 is one whose output 23 is in communication with a display 24th

p0007The operation of the circuit arrangement of FIG. 1 is as follows.

p0008At the beginning of each new accumulator 11 a loading capacity measurement is subjected. For this purpose the battery is fully charged, the fully charged state by the - is determined .DELTA.V method. Then discharged to the discharge voltage. The integral of the discharge current over the time results in the available capacity. This value forms the basis for the measurement of the instantaneous residual capacity by charging or discharging are integrated over time. The times without measurable discharge are taken into account with a typical value for the Selbstentladestrom.

p0009This charge capacity can - as described below - by the connected electrical load are repeated 20 via a request signal with each loading process, so that manually by pressing a key or time controlled the capacity display is recalibrated. Thus, a relatively accurate indication of the remaining capacity of the batteries is also possible with decreasing due to aging of available cargo capacity.

p0010If the battery cartridge 10 is mechanically and electrically connected to the electric device 20, the assumed to be a sufficient-capacity accumulator 11 feeds the apparatus circuit 21 to the microprocessor circuit 22 and the display 24. At a time point t₀ (see. Fig. 4) provides the microprocessor circuit 22 via the terminals 17 and 14 a request signal S_A of duration t_R to the measuring circuit 12th

p0011The request signal is the same as the signals listed below a digital signal. After a waiting time t_W are the measuring circuit at its terminal 14 an asynchronous serial code word of duration t_C from corresponding to the measured residual capacity of the accumulator eleventh The measured remaining capacity value is displayed via the microprocessor circuit 22 on the display 24 of the device 20, preferably 25, by a so-called bar display, the display 24 shows at the same time also other functions of the electronic device 20 on.

p0012Polling the battery residual capacity can preferably be effected automatically in solid, controlled by the microprocessor circuit 22 time intervals; However, it may also be advantageous to trigger the measurement only by the actuation of a particular key of the device 20th

p0013The circuit diagram shown in Fig. 2 of an accumulator-cassette 30 differs from the circuit diagram of the battery cartridge 10 of FIG. 1 in that, also in the battery cartridge, a display 31 is provided, which is controlled by the measuring circuit 32nd In this way, the remaining capacity of a rechargeable battery 33 can also be detected when the accumulator cartridge stored for 30 separated from the electrical device 20 of FIG. 1 and is stored. The display 31 of FIG. 2 also has a LC-bar display. a digital display or an alphanumeric display can take the place of this type of display. If the display shows only a small capacity of the battery 11 (FIG. 1) or 33 (FIG. 2), so the battery cartridge has to be inserted in the conventional manner in a charger that is connected to the AC mains.

p0014According to the circuit diagram of FIG. 3, a charger 41 is integrated into a battery cartridge 40 which is in communication with terminals 42 and 43 of the battery cartridge 40 and to the positive and the negative pole of an accumulator 44th Such a battery cartridge 40 can be connected for charging or recharging of the rechargeable battery 44 with its terminals 42 and 43 to an adapter 46 which is connected to the AC network via a cable 47th The state of charge or the current capacity of the battery 46 can then be measured in the manner described above by means of a measuring circuit 45 and, for example, with a not shown in Fig. 3 display (see FIG. Display 31 in Fig. 2) are displayed.

p0015When measuring circuit 12, 32, 45 is suitable, an integrated circuit of Panasonic called SKC 025/035/045.