Battery charger
First Claim
1. A method of charging rechargeable cells or batteries, comprising the steps of:
- charging the cell or battery with a constant initial charging current,periodically interrupting the charging current to provide a current-off interval of fixed duration,sampling the resistance-free voltage Vo at a fixed time during each current-off interval,compiling the values for Vo with respect to the time t elapsed since commencement of charging,analyzing the compiled values for Vo and t to locate one or more points characteristic of the onset of overcharge,choosing a overcharge reference voltage VREF as a function of one or more of the characteristic points,adjusting the charging current periodically such that Vo does not exceed VREF, whereby significant overcharge is avoided.
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Accused Products
Abstract
A battery charge is provided which automatically controls the charging process independent of individual battery construction or temperature. Control of the charging process is achieved by periodically interrupting the charging current, determining resistance-free voltage of the battery in fixed intervals after interruptions of current, and comparing the resistance-free voltage with a reference voltage. Reference voltage is automatically determined for each recharging subject by analyzing the change in resistance-free voltage with respect to time during an initial, constant current period to locate certain characteristic points indicative of the onset of overcharge. The charging current is reduced as necessary, so that the resistance-free voltage does not exceed the reference voltage and significant overcharge is avoided.
46 Citations
7 Claims
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1. A method of charging rechargeable cells or batteries, comprising the steps of:
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charging the cell or battery with a constant initial charging current, periodically interrupting the charging current to provide a current-off interval of fixed duration, sampling the resistance-free voltage Vo at a fixed time during each current-off interval, compiling the values for Vo with respect to the time t elapsed since commencement of charging, analyzing the compiled values for Vo and t to locate one or more points characteristic of the onset of overcharge, choosing a overcharge reference voltage VREF as a function of one or more of the characteristic points, adjusting the charging current periodically such that Vo does not exceed VREF, whereby significant overcharge is avoided. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification