Battery Cell Balancing via Parallel Resistor Self-Discharge
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Solution Overview
Problem
Batteries connected in series face cell imbalance issues during charging, leading to degraded performance and unpredictable service life, as the lower capacity battery affects the entire set, and conventional solutions require low voltage charging, which is not energy efficient.
Innovation Solution
A device and method that reduces the charging current to batteries exceeding a preset voltage by incorporating a resistor in parallel, allowing self-discharge and balancing the capacity of all batteries, eliminating the need for constant voltage or current charging constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If batteries are connected in series to achieve high voltage, then efficiency increases and cost decreases, but cell imbalance occurs during charging which degrades overall battery performance
Solution Approach 1:
The patent divides the battery system into individually controllable modules, with each battery cell equipped with its own charging control circuit. This segmentation allows independent monitoring and control of each cell's charging process, preventing cell imbalance from degrading overall system performance while maintaining high voltage through series connection.
2Reliability
If conventional charging methods are used for series-connected batteries, then charging can be performed, but low voltage charging is required which reduces energy efficiency due to AC to DC conversion losses
Solution Approach 1:
The patent changes the voltage parameter during the charging process by dynamically adjusting charging voltage based on real-time cell voltage monitoring. This allows high voltage charging to be applied when appropriate, eliminating the need for low voltage charging and associated AC-DC conversion losses, while still preventing overcharging through continuous parameter adjustment.
3Reliability
If complex circuitry is used to detect and balance uncharged batteries during charging, then cell imbalance can be addressed, but device complexity increases
Solution Approach 1:
The patent implements a self-service charging control system where each battery cell has integrated monitoring and control circuits that automatically detect voltage imbalances and adjust charging parameters without external intervention. This self-service approach achieves cell balancing while minimizing overall system complexity by distributing intelligence across individual cells rather than requiring complex centralized control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively balances battery capacities, prolongs cycle life, and allows for efficient charging without the need for complex circuitry or low voltage conversions, enhancing the reliability and performance of battery systems in applications like electric vehicles.
Implementation Method 1
A device and method that reduces the charging current to batteries exceeding a preset voltage by incorporating a resistor in parallel
Data Source
Figure 1a~1c
Figure 1d~1e
Figure 2a
AI summary
A rechargeable battery system having a plurality of cells in series circuits for high voltage applications. Cells, cell sets and cell packs in series circuits are protected from over-charging with self-discharging devices. The rechargeable battery system is protected from over-charging and over-discharging and charging is controlled to be resumed by an over-charge/over-discharge printed circuit board or the charger.