Dynamic Recharge Threshold for Li-Ion Battery Life Extension
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Solution Overview
Problem
Li-Ion batteries experience accelerated self-discharge and cycle life degradation when exposed to high cell voltage over long periods, especially in hearing devices or accessories, due to fixed recharge thresholds that do not account for dynamic changes in battery state and temperature.
Innovation Solution
A method and charger system that dynamically adjust the recharge threshold voltage and end of charge voltage based on the number of recharge cycles, reducing stress on the battery by decreasing these values over time, and resetting them when the battery is disconnected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed recharge threshold voltage is used for charging the battery, then the charging process is simple and reliable, but the battery experiences accelerated self-discharge and cycle life degradation when exposed to high cell voltage over long periods
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed recharge threshold voltage to a dynamic threshold that changes based on the number of recharge cycles. The recharge threshold voltage is decreased after each complete recharge cycle, adapting the charging behavior to the battery's aging state. This resolves the contradiction by making the charging control complex enough to protect battery life but systematic enough to remain implementable.
Solution Approach 2:
The patent changes the parameter of recharge threshold voltage from a constant value to a variable that decreases with each recharge cycle. This parameter change allows the system to reduce charging stress on aged batteries, extending cycle life while maintaining a relatively simple control mechanism that only requires counting cycles and adjusting the threshold accordingly.
2Reliability
If the battery remains connected to the charger for extended periods, then the battery is continuously topped up, but the battery experiences accelerated self-discharge and degradation due to prolonged exposure to high cell voltage
Solution Approach 1:
The patent implements periodic action by performing complete recharge cycles only when the battery voltage falls below the dynamic recharge threshold, rather than continuously charging. This creates a periodic charging pattern that avoids prolonged exposure to high cell voltage, reducing battery degradation while still maintaining adequate charge levels over extended periods.
Solution Approach 2:
The patent applies partial action by not continuously charging the battery to full voltage, but instead allowing it to discharge below the dynamic threshold before recharging. This partial charging approach reduces the duration of high voltage exposure, protecting battery health while still providing sufficient charge for normal operation.
3Reliability
If the recharge threshold voltage is dynamically adjusted based on recharge cycle count, then battery degradation is reduced, but the charging control algorithm becomes more complex
Solution Approach 1:
The patent applies self-service by having the charging system automatically adjust its own parameters based on the number of recharge cycles performed. The controller counts cycles and autonomously decreases the recharge threshold voltage without requiring external intervention or complex user input, simplifying the overall system while extending battery life.
Solution Approach 2:
The patent implements feedback by using the recharge cycle count as a feedback parameter to adjust the recharge threshold voltage. The system monitors the number of complete cycles and uses this information to dynamically modify the charging behavior, creating a closed-loop control system that protects battery health through adaptive parameter adjustment.
Data Source
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AI summary
The invention relates to a method of operating a charger for a battery, the method comprising: - setting an end of charge voltage (EOCV) and a recharge threshold voltage (RTV) to initial values and charging the battery until reaching the end of charge voltage (EOCV) upon detection that the battery has been connected to the charger, - performing the following steps in a loop until the battery is disconnected from the charger: if a state of charge (SOC) voltage of the battery falls below the recharge threshold voltage (RTV), decreasing the recharge threshold voltage (RTV) and charging the battery until reaching the end of charge voltage (EOCV).