Battery Pack Voltage Threshold Control for Capacity Preservation
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Solution Overview
Problem
Lithium-ion secondary batteries in battery packs deteriorate rapidly when left in a high voltage state, as the existing overcharge protection circuit does not function until the voltage exceeds the overcharge detection threshold, leading to prolonged high voltage exposure and capacity loss.
Innovation Solution
A battery pack with a measurement unit, protection unit, and control unit that monitors terminal voltage and current, switching from a low-power sleep mode to a high-power normal mode when the voltage approaches the overcharge detection level, ensuring the battery is not left in a high voltage state by actively lowering the voltage within the full charge to overcharge detection voltage range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the battery is charged to full charge voltage (4.1V or 4.2V) and allowed to stand in this high voltage state, then the charging capacity is maximized, but the battery deteriorates rapidly and discharge capacity is reduced
Solution Approach 1:
The control unit performs preliminary action by detecting when the battery voltage reaches the full charge voltage before the overcharge detection voltage, and proactively switches from sleep mode to normal mode to activate the load. This prevents the battery from remaining in the high voltage state for extended periods, thereby avoiding rapid deterioration while still achieving full charging capacity.
2Use of energy by moving object
If the battery pack uses sleep mode to reduce power consumption, then energy efficiency is improved, but the battery may remain in high voltage state causing deterioration
Solution Approach 1:
The control unit performs preliminary action by detecting when the battery voltage reaches the full charge voltage while in sleep mode, and proactively switches to normal mode to activate the load. This prevents the battery from remaining in the high voltage state for extended periods, thereby avoiding rapid deterioration while still achieving full charging capacity during sleep mode operation.
Data Source
AI summary
A battery pack having a secondary battery; a measurement unit measuring a terminal voltage and a current of the secondary battery; a protection unit preventing the secondary battery from being overcharged when the terminal voltage measured by the measurement unit is equal to or higher than an overcharge detection voltage; and a control unit receiving the terminal voltage and current measured by the measurement unit, the control unit having a first mode and a second mode in which current is less consumed than the first mode. A voltage in a range of from a full charge voltage to less than the overcharge detection voltage is defined as a voltage threshold. The control unit changes from the first mode to the second mode when a state in which a transition requirement is satisfied lasts for a predetermined period of time.