Method for charging a NIMH battery, a battery charger and a system comprising a battery charger and a hearing device
First Claim
1. A method for charging a NiMH battery of a hearing device, the method comprising:
- estimating a state of charge of the NiMH battery,wherein the NiMH is physically coupled to a hearing device;
determining an end of charging time based on the estimated state of charge;
measuring a temperature Tbat representative of a temperature of the NiMH battery;
determining a threshold voltage Vth dependent on the measured temperature Tbat;
applying a charging current with a rate from 0.9 C to 2.1 C to the NiMH battery;
repeatedly measuring a further temperature Tbat′
representative of the temperature of the NiMH battery while applying a charging voltage;
adapting the charging voltage based on the measured further temperature Tbat′
; and
upon reaching the threshold voltage, applying a voltage substantially equal to the threshold voltage to the NiMH battery until the end of charging time is reached.
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Accused Products
Abstract
The present invention provides a method for charging a NiMH battery, comprising estimating a state of charge of the battery (100), determining an end of charging time based on the estimated state of charge (200), applying a constant charging current with a rate in the range from 0.9 C to 2.1 C to the battery until a threshold voltage is reached (300), upon reaching the threshold voltage, applying a constant charging voltage substantially equal to the threshold voltage to the battery (400) and continuing applying the constant charging voltage to the battery until the end of charging time is reached (500). Furthermore, a battery charger adapted to perform such a method as well as a system comprising such a battery charger and a hearing device powered by a NiMH battery are given.
10 Citations
17 Claims
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1. A method for charging a NiMH battery of a hearing device, the method comprising:
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estimating a state of charge of the NiMH battery, wherein the NiMH is physically coupled to a hearing device; determining an end of charging time based on the estimated state of charge; measuring a temperature Tbat representative of a temperature of the NiMH battery; determining a threshold voltage Vth dependent on the measured temperature Tbat; applying a charging current with a rate from 0.9 C to 2.1 C to the NiMH battery; repeatedly measuring a further temperature Tbat′
representative of the temperature of the NiMH battery while applying a charging voltage;adapting the charging voltage based on the measured further temperature Tbat′
; andupon reaching the threshold voltage, applying a voltage substantially equal to the threshold voltage to the NiMH battery until the end of charging time is reached. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A battery charger for charging a NiMH battery in a hearing device, the battery charger comprising:
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a controllable current source; a connector for connecting the current source with the NiMH battery; a state of charge estimator for estimating a state of charge of the NiMH battery, a timer; a temperature sensor configured to measure a temperature Tbat of the NiMH battery; a voltage sensor for measuring a charging voltage applied to the NiMH battery; and a control unit, wherein the control unit is physically or electronically coupled to the current source, the state of charge estimator, the timer, the temperature sensor, and the voltage sensor, and wherein the control unit, the current source, the state of charge estimator, the timer, the temperature sensor, and the voltage sensor are configured to determine a threshold voltage Vth, a time estimate for charging the NiMH battery, and a charging voltage for the NiMH at least partially based the temperature Tbat of the NiMH battery, wherein the battery charged is configured to charge a hearing device. - View Dependent Claims (13, 14, 15, 16, 17)
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Specification