Battery FCC Estimation Using Rest-State OCV After Charging
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Solution Overview
Problem
Existing battery capacity estimation methods fail to update the full charge capacity (FCC) accurately due to users not consistently discharging batteries to a mandatory correction point, and charging before reaching this point prevents FCC updates.
Innovation Solution
A method that measures open circuit voltage (OCV) after a predetermined charging period to estimate FCC, using a control system with a detection unit, storage unit, and processing unit to calculate FCC based on OCV and temperature, incorporating OCV tables and FCC Offset information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the battery is continuously discharged from a fully charged state to the forced voltage correction point to update FCC, then the FCC can be updated, but the continuous discharge condition is difficult to satisfy in normal use
Solution Approach 1:
Instead of updating FCC through continuous discharge from fully charged state to forced voltage correction point, the patent inverts the approach by measuring OCV after charging the battery to fully charged state and letting it rest for a predetermined period. This inversion allows FCC estimation without requiring continuous discharge conditions, making it practical for normal user scenarios.
Solution Approach 2:
The patent performs preliminary charging of the battery to a fully charged state and allows it to rest for a predetermined period before measuring OCV. This preliminary action ensures the battery reaches a stable state suitable for accurate OCV measurement and subsequent FCC calculation, eliminating the need for continuous discharge conditions.
2Measurement precision
If the battery is charged before being discharged to the forced voltage correction point, then the FCC cannot be updated, but this is common in normal user habits
Solution Approach 1:
The patent fundamentally inverts the traditional FCC update methodology by measuring OCV after charging rather than after discharging. This inversion aligns with normal user habits where batteries are frequently charged but not always fully discharged, enabling FCC updates to occur naturally during regular charging cycles without requiring specific discharge conditions.
Solution Approach 2:
The patent enables the battery management system to automatically estimate FCC during normal charging operations without requiring specific user actions or discharge conditions. The system uses readily available OCV measurements from the charging process itself, making the FCC update mechanism self-sufficient and compatible with diverse user behaviors.
3Productivity
If OCV measurement method is used to estimate FCC, then FCC can be updated frequently without continuous discharge, but temperature compensation and design capacity data are required
Solution Approach 1:
The patent makes the OCV measurement serve multiple functions: it not only indicates the state of charge but also enables FCC estimation when combined with temperature data and design capacity information. By storing OCV-SOC correspondence data and design capacity data at different temperatures, the system uses a single OCV measurement to achieve both SOC determination and FCC estimation, reducing the need for separate measurement systems.
Solution Approach 2:
The patent introduces temperature as an intermediary parameter that connects OCV measurements to accurate FCC estimation. By incorporating temperature compensation through pre-stored design capacity data at various temperatures, the system bridges the gap between simple OCV measurement and accurate capacity estimation, enabling frequent updates without requiring complex real-time calibration equipment.
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
Enables frequent updates of FCC without requiring continuous discharge, improving accuracy by linking OCV with battery health indicators, and maintaining precision in estimating battery capacity.
Implementation Method 1
an open circuit voltage (OCV) of a battery in a rest state is measured after the battery has been continuously electrically connected to a power source for a predetermined period
Implementation Method 2
The OCV information includes an open circuit voltage table (OCV table) or a function corresponding to different temperatures
Data Source
AI summary
A battery capacity estimation method, and a battery module and an electronic product using the same are disclosed. In the battery capacity estimation method, after a control system of the battery module has judged that a battery has been charged to a fully charged state for a predetermined period and entered a rest state, a detection unit of the control system measures an open circuit voltage and a temperature of the battery, according to which a full charge capacity of the battery is calculated.