Patent ID: 7554294

Claim:
A battery health monitor for monitoring one or more electrical parameters of a battery, the battery including first and second terminals of opposite polarity and configured to produce a direct current (dc) operating voltage at the first terminal, comprising: control circuitry including a memory for storing a digitized sinusoidal waveform, a controller for accessing the waveform, and a digital-to-analog converter (DAC) for converting the accessed waveform into a sinusoidal oscillatory current control signal; a current sink coupled to the first terminal and configured to sink therefrom a sinusoidal oscillatory current responsive to the sinusoidal oscillatory current control signal so as to cause the battery to produce at the first terminal a sinusoidal oscillatory voltage equal to or less than the dc operating voltage that would be present at the first terminal in the absence of the sinusoidal oscillatory current, wherein the current sink comprises a transistor including a control terminal having applied thereto a control terminal voltage that varies responsive to the sinusoidal oscillatory current control signal, and a current path coupled between the first and second terminals and configured to sink the sinusoidal oscillatory current from the first terminal responsive to the control terminal voltage. a resistor connected in series with the transistor current path, the resistor and the transistor current path being connected between the first and second terminals wherein the sinking current produces across the series resistor a sense voltage proportional to a product of a magnitude of the sinusoidal sinking current and a resistance of the series resistor, and an amplifier circuit configured to convert the current control signal to the control terminal voltage in response to the sense voltage; and a voltage sensor configured to sense the oscillatory voltage at the first terminal.