Apparatus and method for utilizing polarization voltage to determine charge state of a battery
First Claim
1. An apparatus for measuring charge state of a battery comprising at least one cell which exhibits a polarization voltage when fully charged, said apparatus comprising:
- a transmitter connected to the battery and operative to apply a charging test signal to the cell when the cell is fully charged, said test signal characterized by at least one transition to a voltage value greater than the voltage of the cell to provide charging signal which is retained for a time sufficient to modify the polarization voltage when present across the cell; and
a receiver connected to the cell and operative to monitor the polarization voltage across the cell to provide an indication of the state of charge of the cell.
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Accused Products
Abstract
An apparatus for measuring charge state of a battery having multiple cells includes a transmitter that is connected to the battery to apply a test signal across the battery. This test signal is preferably a continuous square wave signal having a frequency less than 3 Hz. The test signal alternates between a voltage adequate to charge the battery and a lower voltage, and the charging voltage is retained for a time sufficient to allow a polarization voltage to develop across individual cells. A receiver is connected to the cell to monitor the polarization voltage across a cell as it develops in response to the test signal. This polarization voltage can be monitored for example using a DC voltmeter, or by displaying the voltage versus time waveform. In either case an accurate indication of the state of the charge of the cell is provided.
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Citations
34 Claims
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1. An apparatus for measuring charge state of a battery comprising at least one cell which exhibits a polarization voltage when fully charged, said apparatus comprising:
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a transmitter connected to the battery and operative to apply a charging test signal to the cell when the cell is fully charged, said test signal characterized by at least one transition to a voltage value greater than the voltage of the cell to provide charging signal which is retained for a time sufficient to modify the polarization voltage when present across the cell; and a receiver connected to the cell and operative to monitor the polarization voltage across the cell to provide an indication of the state of charge of the cell. - View Dependent Claims (2, 3, 4, 6, 7, 8)
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5. The apparatus of claim i wherein the battery is connected to a battery charger and a load, and wherein the battery is being charged by the battery charger.
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9. An apparatus for determining charge state of a battery comprising a first positive terminal and a first negative terminal, said battery comprising a cell comprising a second positive terminal and a second negative terminal, said battery connected to and being charged by a battery charger, said apparatus comprising:
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a. transmitter means connected to said first positive terminal and first negative terminal for applying thereto a square wave charging current signal at a selected frequency below about 3 Hz; b. receiver means connected to said second positive terminal and said second negative terminal for receiving a first voltage signal from said cell, said receiver means comprising; filter means for attenuating DC components of said first voltage signal and outputting a filtered second voltage signal; and measuring means connected to said filter means for measuring a characteristic of said second voltage signal, which varies with a polarization voltage of the cell to provide an indication of the charge state of said cell. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A method for determining charge state of a battery comprising at least one cell which exhibits a polarization voltage when fully charged, said method comprising the following steps:
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a. applying a charging test signal across the cell when the cell is fully charged, said test signal characterized by at least one transition to a voltage value greater than the voltage of the cell to provide a charging signal which is retained for a time sufficient to modify the polarization voltage when present across the cell; and b. monitoring the polarization voltage across the cell to provide an indication of the state of charge of the cell. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23)
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24. A method for determining charge state of a battery comprising a first positive terminal and a first negative terminal, said battery comprising a cell comprising a second positive terminal and a second negative terminal, said battery connected to and being charged by a battery charger, said method comprising the following steps:
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a. applying a square wave charging current signal at a selected frequency less than about 3 Hz to said first positive terminal and said first negative terminal; b. obtaining a first voltage signal indicative of cell voltage between said second positive terminal and said second negative terminal; c. passing said first voltage signal through a filter, said filter selected to attenuate DC components of said first voltage signal and to output a filtered second voltage signal; and d. measuring a characteristic of said second voltage signal which varies with a polarization voltage of the cell to determine the charge state of said cell. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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Specification