Battery Charge Stop Detection via Voltage Integration
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Solution Overview
Problem
Conventional rechargeable battery charging methods fail to accurately detect the full charge point, leading to potential overheating, fire, or explosion risks due to incorrect capacity calculations, especially when leak currents are undetected, and existing solutions incorrectly identify issues even if the battery is properly charged.
Innovation Solution
A charge stop point detecting method that integrates charged and discharged capacity based on sequential voltage and current detection, determining the point to stop charging when the absolute value exceeds a predetermined capacity, with a device that includes voltage and current detection and integration capabilities to ensure accurate full charge detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacity is calculated by integrating charging/discharging current, then remaining capacity can be monitored, but detection accuracy deteriorates in the range between ±5 mA due to undetected leak currents
Solution Approach 1:
The patent introduces voltage as an intermediary parameter to detect full charge state. Instead of relying solely on current integration which fails at low currents (±5 mA range), the system monitors voltage changes as a mediator to determine when the battery reaches full charge, bypassing the measurement precision limitation of current detection.
Solution Approach 2:
The patent replaces the electrical measurement system (current integration) with a voltage-based detection system for determining full charge state. This substitution allows the system to overcome the inherent limitation of current detection precision in the ±5 mA range while maintaining the ability to monitor capacity.
2Reliability
If charging stops when calculated capacity reaches rated capacity, then overcharging is prevented, but false trouble detection occurs when calculated capacity differs from actual capacity
Solution Approach 1:
The patent uses voltage as an intermediary criterion to trigger charge stop, rather than relying directly on integrated capacity. By monitoring voltage as a mediator that reflects the true charge state, the system can accurately determine full charge and stop charging accordingly, avoiding false trouble detections that occur when calculated capacity diverges from actual capacity.
Solution Approach 2:
The patent implements a feedback mechanism where voltage information is continuously monitored and used to adjust the charging process. When voltage reaches a threshold indicating full charge, the system receives feedback to stop charging, ensuring accurate overcharge prevention without being affected by accumulation errors in capacity calculation.
3Measurement precision
If voltage is monitored to detect full charge, then charge stop point can be accurately detected, but device complexity increases due to additional detection requirements
Solution Approach 1:
The patent makes the voltage detection system multi-functional by using it for both capacity monitoring and full charge detection. The same voltage measurement infrastructure that exists for general battery management is leveraged to determine charge stop point, eliminating the need for separate detection circuits and reducing overall device complexity.
Solution Approach 2:
The patent merges the voltage detection function with the existing capacity monitoring system. By combining full charge detection with the ongoing voltage monitoring already performed for capacity tracking, the system achieves accurate charge stop point detection without adding separate detection hardware, thus minimizing device complexity.
Data Source
AI summary
After the highest voltage of a rechargeable battery becomes higher than 4.0 V, when the charging current keeps lower than 50 mA for 20 seconds, a first point is detected for stopping charging the battery. Also, after the highest voltage becomes higher than 4.0 V, the charged capacity value and the discharged capacity value are added and subtracted for integrating the charged/discharged capacity if the highest voltage keeps higher than the integration start voltage. When the integration result shows that the battery is charged totally after the highest voltage becomes higher than 4.0 V, and when the absolute value of the integration result becomes larger than 50% of the designed capacity of the battery, the point second is detected for stopping charging the battery.