Battery Pack Open Cell Tap Detection Circuit
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Solution Overview
Problem
Existing battery pack charging systems fail to detect open taps between cells, leading to undetected overcharging due to disconnection or damage, which can damage battery cells.
Innovation Solution
A method and system for detecting open cell taps in battery packs using a detection voltage applied across an electrical impedance coupled to a measurement node, where a break in the circuit path is identified by measuring voltage at the node, and a charger module with resistors and switches determines disconnection by threshold voltage comparison.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage monitoring is performed at taps between battery cells, then overcharging detection capability is improved, but the system cannot detect when taps become disconnected or damaged
Solution Approach 1:
The system performs preliminary detection by applying a test voltage through a switch before normal charging operations. This preliminary action checks the integrity of the circuit path and tap connections in advance, ensuring that the monitoring system can reliably detect overcharging conditions. The test voltage application occurs periodically or at startup, preparing the system for accurate subsequent measurements.
Solution Approach 2:
A test voltage source and switching mechanism are introduced as intermediary components between the battery cells and the monitoring system. This intermediary allows the system to actively probe the circuit path integrity without interfering with normal charging operations. The switch acts as a mediator that isolates the test function from the charging function, enabling both operations to coexist.
2Measurement precision
If a detection voltage is applied across an electrical impedance to detect open taps, then detection accuracy is improved, but additional circuit components and complexity are introduced
Solution Approach 1:
The detection circuit is merged with the existing charging circuitry by sharing common components such as the battery cell connections, measurement nodes, and control logic. The open tap detection function is integrated into the battery management system, allowing a single circuit to perform both charging monitoring and tap integrity detection without requiring completely separate hardware.
Solution Approach 2:
The switching mechanism serves multiple functions: it controls the application of test voltage for open tap detection, manages the charging current flow, and enables different measurement modes. This multi-functional switch reduces the need for additional dedicated components, simplifying the overall circuit design while maintaining detection accuracy.
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
Effectively detects open cell taps and prevents overcharging by accurately measuring voltages across battery cells, ensuring safe charging and extending battery life.
Implementation Method 1
applying a detection voltage across an electrical impedance that is coupled to a measurement node, where the detection voltage exceeds voltage measures at a node disposed between serially coupled battery cells
Data Source
AI summary
A method is provided for detecting an open cell tap condition in a battery pack. The method includes: applying a detection voltage across an electrical impedance that is coupled to a measurement node, where the detection voltage exceeds voltage measures at a node disposed between serially coupled battery cells of the battery pack and the measurement node is coupled by a circuit path to said node; measuring the voltage at the measurement node while the detection voltage is being applied; and detecting a break in the circuit path when the voltage measured at the measurement node is substantially equal to the detection voltage.