Battery charge measurement and discharge reserve time prediction technique and apparatus
First Claim
1. A method of calculating the discharge reserve time of one or more test cells including the steps of:
- obtaining a plurality of data points representing the direct relationship between voltage and charge remaining during an initial discharge of one or more nominal cells;
parameterising the data points to obtain a function representing charge remaining as a function of a single voltage variable, the function terminating at an end voltage corresponding substantially to a voltage level at which the nominal cell(s) is/are considered to be exhausted;
estimating charge remaining directly from the cell voltage of said test cell(s) during a discharge in accordance with said function; and
calculating the discharge reserve time of said test cell(s) from said estimated charge remaining.
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Accused Products
Abstract
A method of testing one or more cells and parameterising the results in order to obtain a characteristic curve/function from which cell discharge reserve time can be predicted from cell voltage. The test involves obtaining a plurality of data points representing the voltage of a cell as a function of charge remaining, and parameterising the data points to obtain a function representing cell voltage and charge remaining. The function allows charge remaining to be calculated from cell voltage. The invention also provides for a device for measuring capacity and predicting discharge reserve time of a cell, the device including a voltage and current measuring means adapted to measure the voltage and load current of a cell. The device also includes a timing means so that a number of voltage and current data points can be obtained with respect of time. The data points are parameterised and the device produces a function relating charge remaining to cell voltage whereby the charge remaining can be determined by measuring the cell voltage.
119 Citations
38 Claims
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1. A method of calculating the discharge reserve time of one or more test cells including the steps of:
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obtaining a plurality of data points representing the direct relationship between voltage and charge remaining during an initial discharge of one or more nominal cells;
parameterising the data points to obtain a function representing charge remaining as a function of a single voltage variable, the function terminating at an end voltage corresponding substantially to a voltage level at which the nominal cell(s) is/are considered to be exhausted;
estimating charge remaining directly from the cell voltage of said test cell(s) during a discharge in accordance with said function; and
calculating the discharge reserve time of said test cell(s) from said estimated charge remaining. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A battery charge remaining and capacity measurement and discharge reserve time prediction device including:
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a voltage measurement means adapted to measure the voltage of a cell or cells;
a current measurement means adapted to measure the present load on the cell or cells;
a timing means adapted so that a substantially simultaneous measurement of voltage, current and time in respect of the cell or cells can be performed, thereby allowing the collection of a plurality of data points relating to the direct relationship between cell voltage and charge remaining; and
a processing means adapted to produce a curve/function relating charge remaining as a single-variable function of cell voltage during an initial discharge of one or more cells, the curve/function terminating at an end voltage corresponding substantially to a voltage level at which the cell(s) is/are considered to be exhausted, and whereby during a subsequent discharge the curve/function allows the processing means to estimate charge remaining directly from the cell(s) voltage; and
wherein the device is adapted to calculate the discharge rate of a cell or cells, the device using the charge remaining and discharge rate to determine the discharge reserve time. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
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22. A method of characterising one or more test cells including the steps of:
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obtaining a plurality of data points representing a relationship between voltage and absolute charge remaining during an initial discharge of one or more nominal cells; and
parameterising the data points to obtain a function representing absolute charge remaining as a function of a single voltage variable, the function terminating at an end voltage corresponding substantially to a voltage level at which the nominal cell(s) is/are considered to be exhausted, and whereby during a subsequent discharge the function allows the absolute charge remaining to be estimated from the cell(s) voltage. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30)
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31. A battery charge remaining and capacity measurement and discharge reserve time prediction device including:
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a voltage measurement means adapted to measure the voltage of a cell or cells;
a current measurement means adapted to measure the present load on the cell or cells;
a timing means adapted so that a substantially simultaneous measurement of voltage, current and time in respect of the cell or cells can be performed, thereby allowing the collection of a plurality of data points relating to the direct relationship between cell voltage and charge remaining; and
a processing means adapted to produce a curve/function relating absolute charge remaining as a single-variable function of cell voltage during an initial discharge of one or more cells, the curve/function terminating at an end voltage corresponding substantially to a voltage level at which the cell(s) is/are considered to be exhausted, and whereby during a subsequent discharge the curve/function allows the processing means to estimate absolute charge remaining directly from the cell(s) voltage. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38)
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Specification