Battery Capacity Estimation via Resting Voltage Measurement
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Solution Overview
Problem
Existing methods for updating the full charge capacity of rechargeable batteries fail to accurately reflect the battery's state due to user behavior, leading to infrequent or absent updates, which results in inaccurate reserve calculations and state-of-charge gauging, particularly in devices like mobile phones where batteries rarely rest at low states of charge.
Innovation Solution
A system that modifies the charging process by inserting a rest point during charging, allowing the battery to relax and measure resting voltage, then resumes charging to estimate capacity based on measured voltages and coulomb counts, ensuring accurate updates without disrupting user behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the battery is discharged to low state of charge to obtain relaxed voltage measurements, then the full charge capacity can be updated, but the user experience deteriorates due to unexpected battery shutdown or data loss
Solution Approach 1:
The system performs preliminary actions by measuring the terminal voltage at the beginning of charging (when battery is near full charge) and at the end of charging (after a rest period), before actually discharging the battery to low state of charge. This allows capacity estimation without forcing the battery into a state that would cause operational problems.
Solution Approach 2:
The system uses an intermediary approach by utilizing voltage measurements taken during normal charging cycles as a proxy for capacity assessment. Instead of directly discharging to low SOC to measure capacity, it uses the charging voltage profile and rest period voltage decay as intermediate indicators to estimate full charge capacity, avoiding the harmful low SOC state.
2Measurement precision
If the battery charging process is interrupted frequently to measure resting voltage, then the full charge capacity can be accurately updated, but the charging time increases
Solution Approach 1:
The system applies partial action by taking only the essential voltage measurements needed for capacity estimation - specifically at the beginning and end of charging cycles - rather than continuously interrupting charging. The rest period is kept minimal (just long enough to allow voltage stabilization) rather than extending the full charging process, thus obtaining sufficient measurement precision without excessive time loss.
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 enables reliable and accurate updates of the full charge capacity, improving state-of-charge calculations and preventing data loss from system brown-outs by allowing rested OCV measurements, even in devices with background services.
Implementation Method 1
The system then interrupts the charging process to allow the battery to relax to a resting voltage
Data Source
AI summary
Some embodiments of the present invention provide a system that accurately and reliably updates a full charge capacity of a battery. During operation, the system charges the battery from an initial state to a rest point prior to reaching a fully charged state. The system then interrupts the charging process to allow the battery to relax to a resting voltage. Next, the system measures the resting voltage. The system then resumes the charging process toward the fully charged state. The system subsequently estimates the capacity of the battery based on the measured resting voltage and one or more other parameters.