Battery Fully-Charged Capacity Detection Using No-Load Voltage
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Solution Overview
Problem
Existing methods struggle to accurately detect the fully-charged capacity of batteries without bringing them to a fully-charged or fully-discharged state, especially as capacity decreases with charging/discharging cycles, and are not suitable for all types of batteries.
Innovation Solution
A method involving no-load voltage detection, remaining capacity determination, variation rate calculation, and fully-charged capacity calculation, using first and second no-load voltages to determine remaining capacities and calculate the fully-charged capacity based on the integrated value of charging and discharging currents, without requiring the battery to be fully charged or discharged.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the battery is fully discharged and then fully charged to detect fully-charged capacity, then the detection accuracy is improved, but the charging time increases significantly and the method cannot be used for backup batteries
Solution Approach 1:
The patent applies partial action by detecting fully-charged capacity through incremental charging steps (e.g., charging to 80%, then 90%, then 100%) rather than requiring complete full discharge-charge cycles. This allows capacity detection to be performed during regular charging operations without demanding the battery be fully discharged first, significantly reducing time loss while maintaining detection accuracy through multiple measurement points
2Ease of manufacture
If the fully-charged capacity is detected by integrating charge capacity amounts from fully-discharged to fully-charged state, then the detection method is simple, but the battery must be fully discharged before charging which is not practical for most applications
Solution Approach 1:
The patent applies preliminary action by maintaining a record of cumulative charge capacity amounts from previous charging operations. When a charging cycle occurs, the system integrates the charge capacity incrementally and compares it with the remaining capacity ratio to calculate fully-charged capacity, eliminating the need to wait for full discharge before detection can be performed
3Ease of operation
If the fully-charged capacity is estimated based on accumulated charging capacity amount or storage temperature and remaining capacity, then the detection can be performed without full charge/discharge cycles, but the detection accuracy cannot be constantly maintained due to complicated deterioration variations
Solution Approach 1:
The patent applies feedback by continuously monitoring the relationship between charge capacity amounts and remaining capacity ratios during charging operations. The system uses this feedback to dynamically adjust and refine the fully-charged capacity detection, comparing actual charging behavior against expected patterns to maintain high accuracy despite varying deterioration conditions, temperature changes, and usage patterns
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 method allows for accurate detection of fully-charged capacity without state changes, improving measurement accuracy and enabling regular capacity assessments during charging operations, suitable for various battery types including lithium-ion and lithium-polymer batteries.
Implementation Method 1
first and second no-load voltages (VOCV1, VOCV2) of a battery are detected at first no-load timing and second no-load timing in that the battery is brought in a no-load state, respectively
Implementation Method 2
a capacity variation value (δAh) of the battery is calculated based on the integrated value of charging and discharging currents of the battery to be charged/discharged from the first no-load timing to the second no-load timing
Data Source
AI summary
A fully-charged battery capacity detection method detects first and second no-load voltages (VOCV1, VOCV2) of a battery at first no-load timing and second no-load timing, respectively. Further, first and second remaining capacities (SOC1 [%], SOC2 [%]) of the battery are determined based on the first and second no-load voltages, respectively, when the first no-load voltage (VOCV1) falls within a predetermined voltage range. Moreover, a fully-charged capacity (Ahf) of the battery is calculated based on a remaining capacity variation rate (δS [%]) and a capacity variation value (δAh) of the battery. Also, the variation rate of the remaining capacity is calculated based on a difference between the first and second remaining capacities. The capacity variation value of the battery is calculated based on an integrated value of the charging current and discharge currents of the battery to be charged/discharged from the first no-load timing to the second no-load timing.