Abstract: A battery control system for a vehicle includes a battery state estimator configured to obtain a battery cell open circuit voltage (OCV) of a battery in response to a charging system charging the battery to a maximum charging voltage. The system includes a negative voltage determination module configured to determine a negative OCV of the battery based on the obtained cell or battery OCV. The system includes a voltage shift determination module configured to identify a difference between the negative OCV of the battery and a previous negative OCV of the battery. The system also includes a charge voltage module configured to selectively reduce the maximum charging voltage to a reduced maximum charging voltage based on the difference and transmit the reduced maximum charging voltage to the charging system. The charging system is instructed to charge the battery such that the battery does not exceed the reduced maximum charging voltage.

Abstract: A battery control system for a vehicle includes a battery state estimator configured to obtain a battery cell open circuit voltage (OCV) of a battery in response to a charging system charging the battery to a maximum charging voltage. The system includes a negative voltage determination module configured to determine a negative OCV of the battery based on the obtained cell or battery OCV. The system includes a voltage shift determination module configured to identify a difference between the negative OCV of the battery and a previous negative OCV of the battery. The system also includes a charge voltage module configured to selectively reduce the maximum charging voltage to a reduced maximum charging voltage based on the difference and transmit the reduced maximum charging voltage to the charging system. The charging system is instructed to charge the battery such that the battery does not exceed the reduced maximum charging voltage.

Abstract: A method for predicting power capability of a battery pack in a system includes determining an open-circuit voltage of the battery pack via a controller, calculating pack resistance using measured voltage and current during a charge or discharge event, and calculating a maximum current of the pack using the open-circuit voltage and internal resistance. The method includes selecting the lower of an absolute value of each of the calculated maximum discharge current and predetermined current limit, calculating the discharge power capability of the battery pack using the selected lower absolute value, and controlling a state of the system using the calculated power capability. The method also controls the charging current and parameters during a DC fast-charging operation. A system includes the battery pack, electric machine, and controller. The system may be a vehicle having an electric powertrain, with an electric machine powered by the battery pack.

Abstract: A discharge module is configured to determine a change in capacity of the battery between: (i) a measurement of a first open circuit voltage (OCV) of a battery of a vehicle; and (ii) a measurement of a second OCV of the battery. A lookup table is stored in memory and includes reference states of charge (SOCs) indexed by reference OCVs and reference capacities. A relationship module is configured to: from the lookup table, identify a first set of the reference SOCs associated with the first OCV and the reference capacities, respectively; from the lookup table, identify a second set of the reference SOCs associated with the second OCV and the reference capacities, respectively; determine changes in SOC associated with the reference capacities; determine changes in capacity; and determine an equation that relates changes in capacity to capacity based on the changes in capacity and the reference capacities, respectively.

Abstract: A method for predicting power capability of a battery pack in a system includes determining an open-circuit voltage of the battery pack via a controller, calculating pack resistance using measured voltage and current during a charge or discharge event, and calculating a maximum current of the pack using the open-circuit voltage and internal resistance. The method includes selecting the lower of an absolute value of each of the calculated maximum discharge current and predetermined current limit, calculating the discharge power capability of the battery pack using the selected lower absolute value, and controlling a state of the system using the calculated power capability. The method also controls the charging current and parameters during a DC fast-charging operation. A system includes the battery pack, electric machine, and controller. The system may be a vehicle having an electric powertrain, with an electric machine powered by the battery pack.

Abstract: A method for evaluating a battery employed in an application includes calculating a differential voltage during a charging event, evaluating the differential voltage to determine a peak state of the differential voltage, determining a state of charge of the battery based upon the peak state of the differential voltage, and controlling operation of the application in response to the state of charge.

Abstract: Methods and systems for depowering a rechargeable battery in a rapid, yet controlled, manner. The methods comprise (i) providing a depowering medium comprising expanded graphite (and optionally, one or more dispersible non-ionic electric conductors) dispersed in a substantially non-ionic aqueous medium; (ii) contacting terminals of the battery with the depowering medium; and (iii) maintaining contact between the depowering medium and terminals for a period of time sufficient to depower the battery. The systems comprise (i) the depowering medium; and (ii) a container configured to receive a battery and the depowering medium such that the battery body is contacted with the depowering medium prior to the terminals.

Abstract: A method for evaluating a battery employed in an application includes calculating a differential voltage during a charging event, evaluating the differential voltage to determine a peak state of the differential voltage, determining a state of charge of the battery based upon the peak state of the differential voltage, and controlling operation of the application in response to the state of charge.

Abstract: A method and apparatus for determining the state of charge of a lead-acid battery. The present invention includes steps to determine a current-based state of charge while accounting for such factors as current, temperature, charge efficiency, parasitic losses and self-discharge. The present invention is capable of measuring and/or calculating the open circuit voltage during and after operation to determine a voltage-based state of charge while compensating the open circuit voltage for its transient behavior and accounting for the voltage shift caused by charge events. The correlation of the open circuit voltage to the state of charge is dependent on the battery's mode of operation. The present invention is adaptive to battery aging by updating the battery resistance, correcting coulomb errors, and accounting for capacity degradation while in operation.

Abstract: A method and apparatus for determining the state of charge of a lead-acid battery. The present invention includes steps to determine a current-based state of charge while accounting for such factors as current, temperature, charge efficiency, parasitic losses and self-discharge. The present invention is capable of measuring and/or calculating the open circuit voltage during and after operation to determine a voltage-based state of charge while compensating the open circuit voltage for its transient behavior and accounting for the voltage shift caused by charge events. The correlation of the open circuit voltage to the state of charge is dependent on the battery's mode of operation. The present invention is adaptive to battery aging by updating the battery resistance, correcting coulomb errors, and accounting for capacity degradation while in operation.

Abstract: A method for determining state of charge (SOC) of a battery system based upon an equivalent circuit of the battery system. A potential and resistance of the equivalent circuit are computed. The method uses a least squares regression means, and includes: providing a plurality of data points as a starting point based upon determinations including measurement or prior computation, wherein the determinations include a determination of a voltage of the battery system; weighting the plurality of data points; and computing values of the resistance and potential based upon weighted data points using recursive formulas, wherein only a state at a previous time is reflected respectively.

Abstract: A method for determining state of charge (SOC) of a battery system based upon an equivalent circuit of the battery system. A potential and resistance of the equivalent circuit are computed. The method uses a least squares regression means, and includes: providing a plurality of data points as a starting point based upon determinations including measurement or prior computation, wherein the determinations include a determination of a voltage of the battery system; weighting the plurality of data points; and computing values of the resistance and potential based upon weighted data points using recursive formulas, wherein only a state at a previous time is reflected respectively.

Abstract: A method and apparatus for determining the state of charge of a battery including the steps of determining whether the battery is in a charge decreasing, sustaining or increasing mode, integrating the charge going in and out of the battery to determine a current-based state of charge measurement if the battery is in a charge increasing or sustaining mode, and determining the open circuit voltage to determine an open circuit-based state of charge measurement if the battery is in a charge decreasing mode.