Dynamic Charge Current Adjustment for End-of-Life Battery Extension
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Solution Overview
Problem
Lithium-ion secondary batteries face a trade-off between charge duration and cycle degradation, with high charge current reducing service life and low charge current increasing duration, and there is a need to continue using batteries beyond their end of life without rapid capacity and safety decreases.
Innovation Solution
A charging system that calculates the full charge capacity and degree of variation, detects when the battery is at the end of life, and adjusts the charge current or power to maintain efficient charging while prolonging battery life by switching to a lower charge value when degradation is high.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If charge current is increased to reduce charge duration, then charge duration is improved, but charge/discharge cycle degradation increases reducing service life
Solution Approach 1:
The patent applies dynamics by making the charge current adjustable based on battery degradation level. The system transitions from a static charge current approach to a dynamic one where the current is modified according to the detected degradation level, allowing optimal charging conditions to be maintained throughout the battery's service life.
Solution Approach 2:
The patent changes the charge current parameter based on the battery's degradation level. When degradation exceeds a predetermined threshold, the system reduces the charge current from a first value to a second value, thereby adapting the charging parameters to the battery's current state and preventing excessive degradation while maintaining reasonable charge duration.
2Reliability
If charge voltage or charge current is decreased to suppress degradation, then service life is improved, but charge duration becomes long
Solution Approach 1:
The system dynamically adjusts charge parameters based on real-time degradation detection. Instead of using a fixed low charge current that would always prioritize service life over charge speed, the system maintains higher charge currents when degradation is within acceptable limits and only reduces them when degradation exceeds the threshold, thereby optimizing both charge duration and service life.
Solution Approach 2:
The patent implements feedback by continuously detecting the battery's degradation level and using this information to adjust the charge current. The degradation detection unit provides feedback to the charge control unit, which then modifies the charging parameters accordingly, creating a closed-loop control system that balances charge duration and service life extension.
3Reliability
If immediate stop of use is implemented when battery reaches end of life, then safety is improved, but usability decreases
Solution Approach 1:
The system performs preliminary action by detecting degradation trends before the battery reaches a dangerous state. By monitoring the degradation level and comparing it against a predetermined threshold, the system takes preventive measures by adjusting charge parameters before catastrophic failure can occur, thereby maintaining safety while avoiding unnecessary complete shutdowns.
Solution Approach 2:
The patent applies dynamics by transitioning from a static binary state (use or immediate stop) to a dynamic continuum of usage conditions. The system allows continued use with modified charge parameters when degradation is manageable, and only implements protective measures when degradation exceeds safe thresholds, thereby maintaining usability while ensuring safety.
Data Source
AI summary
Even after the battery reaches the last stage of the end of life, the use can be continued. A charging system includes battery pack and charger. During the charge of lithium-ion secondary battery, charge control unit calculates the full charge capacity maintaining rate, sets a first charge current value on the basis of the full charge capacity maintaining rate, and charges the battery. When lithium-ion secondary battery reaches the last stage of the end of life, charge control unit sets a second charge current value lower than the first charge current value set based on the full charge capacity maintaining rate, and charges the battery.