Coin Cell Shelf Life Extension via Voltage Step-Up Converter
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Solution Overview
Problem
Coin cells used in miniature electro-explosive devices face degradation in internal impedance over time, especially under high temperature diurnal cycling, which affects their ability to maintain voltage during high pulse current loads, and increasing cell size is not feasible due to volume constraints.
Innovation Solution
A system comprising a coin cell, a voltage step-up converter/regulator, and a storage capacitor with a resistor, where the converter boosts and regulates the voltage above the threshold required for the firing circuit, allowing the coin cell to operate at a lower voltage while maintaining proper circuit operation and extending shelf life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a larger coin cell with higher discharge rate capability is used, then the internal impedance decreases and voltage maintenance improves, but the volume increases which is not feasible
Solution Approach 1:
A DC-DC converter is introduced as an intermediary device between the coin cell and the firing circuit. The converter receives power from the coin cell at lower voltage and higher current, converts it to higher voltage and lower current, and delivers it to the firing circuit. This mediator allows the system to maintain the coin cell at small size while achieving the required voltage output for reliable firing circuit operation.
Solution Approach 2:
The system changes the voltage and current parameters dynamically through the DC-DC converter. The converter operates in boost mode to step up the voltage from the coin cell when high voltage is needed for the firing circuit, and in buck mode when lower voltage is sufficient. This parameter transformation allows the small coin cell to effectively deliver power at different voltage levels without requiring physical size increase.
2Reliability
If the coin cell operates at high voltage to meet firing circuit requirements, then the firing circuit operates reliably, but the power loss increases and efficiency decreases
Solution Approach 1:
The DC-DC converter dynamically adjusts its operation mode based on the voltage requirements of the firing circuit and the state of the coin cell. It switches between boost mode (when coin cell voltage is below the firing threshold), buck mode (when voltage is sufficient), and standby mode (when capacitor is charged). This dynamic operation optimizes power transfer efficiency and minimizes energy losses compared to continuous high-voltage operation.
Solution Approach 2:
The system employs periodic charging cycles where the capacitor is charged during intervals when the firing circuit does not require power. The converter operates in boost mode during charging phases, then switches to standby or buck mode when the capacitor voltage is sufficient. This periodic action allows efficient energy transfer while maintaining reliable firing capability, reducing overall power loss.
3Duration of action of stationary object
If the coin cell is subjected to high temperature diurnal cycling, then the internal impedance degrades over time, but the shelf-life needs to be extended
Solution Approach 1:
The system incorporates a storage capacitor that is charged in advance during periods when high current is not required. This pre-charged capacitor serves as a buffer that can immediately supply high pulse current when the firing circuit needs to operate, cushioning the coin cell from high current stress that would accelerate impedance degradation during temperature cycling. This protective buffering extends the effective shelf-life of the coin cell.
Solution Approach 2:
The DC-DC converter acts as a protective intermediary that manages the power extraction from the coin cell. By controlling the charging current and operating mode, the converter prevents excessive current draws that would heat the coin cell and accelerate impedance degradation during temperature cycling. The converter mediates between the coin cell and the firing circuit, protecting the coin cell while enabling reliable firing operation.
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 configuration increases the shelf life of the coin cell by tolerating internal impedance degradation, ensuring reliable operation and increased power output at higher current loads with high efficiency and low cost.
Implementation Method 1
a voltage step up converter/regulator, configured to step up the voltage of output from the coin cell
Implementation Method 2
a storage capacitor receiving output from the voltage step up converter
Data Source
AI summary
A system is provided for extending the shelf life capacity of a coin cell, the system utilizing a coin cell; a voltage step up converter/regulator, configured to step up the voltage of output from the coin cell and the storage capacitor; and a storage capacitor receiving output from the voltage step up converter/regulator.