Battery Pack Dynamic Voltage Control for Cell Lifespan
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Solution Overview
Problem
Lithium-ion secondary cells degrade quickly when left in a high voltage state for extended periods, especially when unused, leading to reduced discharge capacity and shortened lifespan, as existing technologies lack effective means to automatically adjust voltage settings.
Innovation Solution
A battery pack with a microcomputer-controlled system that monitors the usage state and elapsed time, switching between normal and degradation control modes to prevent high voltage states by increasing power consumption when the cell is unused for a predetermined period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the secondary cell is charged to high voltage (4.1V or 4.2V) for high capacity mode, then the discharge capacity is improved, but the cell degradation accelerates and lifespan is shortened when left unused for long periods
Solution Approach 1:
The patent implements dynamic voltage management by automatically switching between high voltage mode (4.1V/4.2V) and low voltage mode (3.7V-3.8V) based on the elapsed time since the cell was left unused. The system transitions from static charging voltage selection to dynamic adjustment, where the full charge voltage is changed according to time-based conditions detected by the control unit, thereby resolving the contradiction between capacity and lifespan.
Solution Approach 2:
The patent changes the voltage parameter of the secondary cell based on the elapsed time of unused state. When the elapsed time exceeds a predetermined threshold, the system lowers the full charge voltage from high voltage (4.1V/4.2V) to low voltage (3.7V-3.8V). This parameter change directly addresses the contradiction by adjusting the voltage level to prevent degradation while maintaining capacity when needed.
2Adaptability or versatility
If the user manually switches between high capacity mode and long-life mode, then the cell can be optimized for different uses, but the system complexity increases and user error may occur
Solution Approach 1:
The patent implements self-service by enabling the battery pack to automatically determine and switch between high capacity mode and long-life mode based on the elapsed time of unused state. The control unit autonomously detects whether the cell has been left unused for a prolonged period and automatically adjusts the full charge voltage accordingly, eliminating the need for manual user intervention and reducing operational complexity while maintaining adaptability.
Solution Approach 2:
The patent employs feedback mechanisms where the control unit continuously monitors the elapsed time since the cell was left unused and uses this information to automatically adjust the charging voltage. The system receives feedback about the unused time period and responds by switching between voltage modes, creating a closed-loop control system that adapts to usage patterns without requiring manual input from the user.
3Use of energy by moving object
If the cell is left in high voltage state for extended periods, then the energy density is maintained, but the degradation speed increases significantly
Solution Approach 1:
The patent applies preliminary anti-action by proactively lowering the full charge voltage when the control unit detects that the elapsed time of unused state has exceeded a predetermined threshold. Instead of waiting for degradation to occur, the system preemptively adjusts the voltage to a lower level (3.7V-3.8V) to prevent degradation, thereby counteracting the harmful effect before it significantly impacts cell lifespan while still maintaining acceptable energy density.
Data Source
AI summary
A battery pack includes a secondary cell, a selection unit, a judging unit, an elapsed time period comparing unit, and a control unit. The selection unit selects either a first operation state or a second operation state. The control unit controls the selection unit to switch from the first operation state to the second operation state when the elapsed time period is longer than a predetermined time period. The control unit also controls the selection unit to switch from a second operation state to a first operation state either (a) when judged as being in an used state by the judging unit while the second operation is selected (b) when a voltage of the second cell becomes equal to or less than a second voltage threshold value which is smaller than a first voltage threshold value while the second operation state is selected.