Battery charger
First Claim
1. A battery charger comprising means for supplying a cyclic sequence of charging pulses of charging current of a predetermined charging pulse period of the order of several seconds to a battery interspersed with discharge pulses of a predetermined discharge pulse period of the order of greater than a second for discharging the battery during the charging pulse interpulse period, means for measuring the change in the battery terminal voltage over a further predetermined period during one of said pulse periods, and means for processing said change of battery voltage to derive a condition for terminating the pulse charging of the battery in response to the measured voltage change.
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Accused Products
Abstract
A battery charger is provided which supplies pulses of charging current to a battery and discharges the battery between each charging pulse. The change in the battery terminal voltage over a predetermined period during each charging pulse is measured, and the pulse charging is terminated when a parameter of the measured voltage change exhibits a predetermined characteristic. Pulse charging may be terminated as a result of the measured voltage change exceeding a predetermined threshold or as a result of the detection of a point of inflexion in the variation of measured voltage change with time.
217 Citations
14 Claims
- 1. A battery charger comprising means for supplying a cyclic sequence of charging pulses of charging current of a predetermined charging pulse period of the order of several seconds to a battery interspersed with discharge pulses of a predetermined discharge pulse period of the order of greater than a second for discharging the battery during the charging pulse interpulse period, means for measuring the change in the battery terminal voltage over a further predetermined period during one of said pulse periods, and means for processing said change of battery voltage to derive a condition for terminating the pulse charging of the battery in response to the measured voltage change.
- 10. A battery charger comprising means for supplying pulses of charging current to a battery and means for discharging the battery by a current discharge pulse during the interpulse period characterised by means for measuring the change in the battery terminal voltage over a predetermined period during one of said pulses, means for terminating the pulse charging of the battery when the measured battery voltage change exhibits a predetermined characteristic, and means for modifying the current through the battery in response to the change in battery temperature, wherein the current modifying means comprise means for modifying the amplitude of the current in the first portion of each charging pulse such that the amplitude increases with increasing internal battery temperature, and means for modifying the amplitude of the current in a second portion of each charging pulse to maintain the mean charging current substantially constant.
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14. A battery charger comprising means for supplying pulses of charging current to a battery and means for discharging the battery by a current discharge pulse during the interpulse period characterised by means for measuring the change in the battery terminal voltage over a predetermined period during one of said pulses, means for terminating the pulse charging of the battery when the measured battery temperature exhibits a predetermined characteristic, and means for modifying the current through the battery in response to the change in battery temperature, wherein the terminating means is adapted to detect a point of inflection in the variation of the measured voltage with time, and to terminate pulse charging when a point of inflection is detected, and wherein a series of consecutively sampled measurements of the voltage change are averaged to smooth the measurement of the voltage change and to delay termination of pulse charging.
Specification