Lithium Battery Depassivation Algorithm for Fire Detection
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Solution Overview
Problem
Lithium-ion batteries in fire detection systems face passivation issues due to non-use, leading to reduced capacity and false-low battery readings, especially in wireless communication systems where batteries are not regularly discharged, causing power supply problems during emergencies.
Innovation Solution
A method involving a depassivation algorithm that applies a load to the battery based on its passivation and depletion state, followed by a maintenance pulse to prevent re-passivation, ensuring the battery remains active and functional by periodically evaluating and maintaining its state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If lithium-ion batteries are used for long-term backup power in wireless fire detection systems, then energy density and duration of action are improved, but passivation occurs during non-use leading to reduced capacity and false-low battery readings
Solution Approach 1:
The system performs preliminary evaluation of battery state (passivation vs. depletion) before taking action. By measuring voltage under load and analyzing the response curve, the system determines the battery's actual state and applies appropriate algorithms (depassivation or recharge) in advance of any power failure, ensuring the battery is ready for use.
Solution Approach 2:
The system implements periodic battery evaluation and maintenance algorithms that run at scheduled intervals (e.g., daily, weekly). This periodic action prevents passivation from occurring in the first place by regularly activating the battery, or quickly removes passivation when detected, ensuring the battery remains reliable for backup power.
2Reliability
If a load is applied to breakdown the passivation crystalline structure, then battery capacity is restored, but the process takes time and requires specific current levels
Solution Approach 1:
The system dynamically adjusts the depassivation algorithm based on the measured battery state. By analyzing the voltage response curve characteristics, the system determines the degree of passivation and selects appropriate current levels and durations, optimizing the balance between restoring capacity and minimizing time loss.
Solution Approach 2:
The system changes key parameters (current level, duration, pulse pattern) of the depassivation process based on the detected battery state. Different passivation levels require different parameter settings, and the system adapts these parameters dynamically to achieve effective depassivation while minimizing time and energy consumption.
3Reliability
If the battery is evaluated and maintained periodically, then passivation is prevented and battery health is maintained, but system complexity increases
Solution Approach 1:
The system performs self-diagnosis and self-maintenance by automatically evaluating battery state and applying appropriate algorithms without external intervention. The controller monitors battery voltage under load, detects passivation conditions, and executes depassivation or recharge algorithms autonomously, reducing the need for complex external maintenance systems.
Solution Approach 2:
The system uses feedback from voltage measurements under load to determine battery state and adjust maintenance actions. By continuously monitoring the voltage response curve and comparing it against known patterns, the system receives feedback on battery health and automatically adjusts its maintenance strategy, simplifying the overall control architecture.
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 reactivates lithium-ion batteries, preventing passivation and ensuring they supply power as intended, thereby enhancing the reliability of fire detection systems by maintaining battery health and capacity over time.
Implementation Method 1
Passivation may be eliminated inside the battery by the application of a sufficiently high current to breakdown/remove the crystalline structure
Implementation Method 2
Lithium ion batteries are often used for this purpose because, for example, they have a much greater energy density than other batteries
Data Source
AI summary
A method of depassivating a battery may include receiving a determined state of the battery and applying, depending on the determined state, a depassivation algorithm to the battery. The algorithm may include applying a load across the battery for a predetermined amount of time that is dependent on the degree of battery passivation.