Battery Charging Control via Impedance and Voltage Analysis
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Solution Overview
Problem
Existing methods for determining battery chemistry in portable devices assume batteries are in good condition and do not account for varying states of viability, leading to potential overcharging and inefficiencies, especially when multiple cells are involved.
Innovation Solution
A method using terminal voltage measurements before, during, and after charge routines, combined with impedance determination, to differentiate between primary and secondary batteries and assess their condition, ensuring safe charging and balancing of rechargeable battery packs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If prior art methods for determining battery chemistry are used, then battery chemistry can be identified, but the methods fail when batteries are in poor condition or various states of viability
Solution Approach 1:
The patent applies dynamic testing procedures that adapt to the battery's actual condition. Instead of assuming a fixed good state, the system performs multiple voltage measurements at different states of charge and uses impedance spectroscopy to dynamically assess battery health. The charging protocol is adjusted based on real-time measurements, allowing reliable chemistry identification across varying battery conditions including poor condition and different viability states.
Solution Approach 2:
The patent changes multiple parameters simultaneously to achieve accurate battery characterization: voltage measurement points are varied across different charge states, current magnitudes are adjusted during impedance measurements, and frequency ranges are modified during electrochemical impedance spectroscopy. This multi-parameter approach enables reliable chemistry identification regardless of the battery's initial condition or state of charge.
2Productivity
If multiple cells are charged simultaneously, then charging speed is improved, but cell imbalance causes overcharging and reduces battery lifetime
Solution Approach 1:
The patent segments the battery pack into individual cells and measures the state of charge of each cell separately using voltage measurements and impedance spectroscopy. This segmentation allows the system to identify cells with different charge levels and manage them appropriately, preventing overcharging of fully charged cells while maintaining high charging speed by charging multiple cells simultaneously when appropriate.
Solution Approach 2:
The system continuously monitors individual cell voltages and impedance values, providing real-time feedback on cell state of charge. Based on this feedback, the charging protocol is dynamically adjusted: cells that reach full charge are disconnected or have their charging current reduced, while cells that are not yet full continue to charge. This feedback mechanism maintains high productivity while preventing overcharging and extending battery lifetime.
3Loss of time
If high charging current is applied, then charging time is reduced, but the risk of overcharging and energy waste increases
Solution Approach 1:
The patent employs periodic measurements of cell voltage and impedance during the charging process. Instead of continuous monitoring that would be energy-intensive, the system performs measurements at regular intervals and uses these periodic data points to detect when cells reach full charge. This allows high charging currents to be applied for most of the charging cycle (minimizing time loss) while still detecting the endpoint accurately (preventing energy waste from overcharging).
Solution Approach 2:
The system performs preliminary impedance spectroscopy measurements before initiating high-current charging to establish baseline cell characteristics and predict charge acceptance. This preliminary action allows the system to configure an optimized charging profile that maximizes charging speed while built-in safety margins prevent overcharging. The preliminary characterization enables faster charging without increasing the risk of energy waste.
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 determines battery chemistry and state, preventing overcharging and ensuring efficient power usage by identifying suitable batteries for charging and balancing cell levels within rechargeable battery packs.
Implementation Method 1
Impedance determination of the battery is an important feature of the methods of the present invention. The impedance determination is generally performed by flowing a current through the battery, and either by dividing the value of voltage increase by the current flow through the battery, or by any other function of the voltage response of the battery to the current flow through it.
Data Source
AI summary
A battery charge control system including an algorithm for determining whether the battery chemistry of a battery pack for use in a portable electronic device is primary, in which case charging is prevented, or secondary, in which case charging is enabled. The routine operates by measuring the terminal voltage and temperature of the battery under certain predetermined tests, which generally include a combination of voltage and internal impedance tests performed during charge or discharge. Additionally, a method is described to detect and to correct for lack of cell balance within the rechargeable battery pack of a portable electronic device. A cell or cells of the battery pack which are close to depletion, or are completely depleted, are detected, and a discharge/charge routine is executed to provide for optimum recharging of all of the cells of the battery, thus ensuring proper cell balance, and most efficient power usage.