Traction Battery Self-Discharge Monitoring for Internal Short Circuits

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Solution Overview

Problem

Existing monitoring technologies struggle to accurately detect micro-internal short circuits in traction batteries of electric vehicles, especially in environments with electrical interference, leading to potential thermal runaway and safety threats.

Innovation Solution

A method and system for monitoring battery short circuits that involves collecting and analyzing electrical signal information from all cells in a traction battery, performing self-discharge observation, and calculating self-discharge rates to determine the presence of internal short circuits, utilizing a phased approach and thresholds to trigger alarm handling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional BMS monitoring is used to detect thermal runaway, then alarm can be given when thermal runaway occurs, but the situation has already seriously threatened safety and people in the vehicle are threatened

Engineering Contradiction:
Improvesafety detection reliabilityVSAvoiddetection time delay
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent performs preliminary detection of micro-internal short circuits by monitoring self-discharge rates before thermal runaway occurs. The BMS calculates self-discharge rates during static working conditions and compares them against thresholds to identify early signs of battery degradation, enabling preventive action before critical failure occurs.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent replaces conventional thermal and voltage-based monitoring with a self-discharge rate monitoring mechanism. By calculating the rate of voltage decay over time during static conditions, the system detects micro-internal short circuits that conventional methods miss, substituting direct thermal/voltage measurement with a derived computational parameter.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If voltage monitoring is performed during vehicle operation, then real-time data can be collected, but electrical interference from vehicle-mounted devices causes data accuracy to deteriorate

Engineering Contradiction:
Improvedata collection frequencyVSAvoidvoltage measurement accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent performs self-discharge rate monitoring during periodic static working conditions when the vehicle is parked or stopped. Instead of continuous monitoring during operation, the system utilizes naturally occurring static periods to collect clean voltage data, eliminating electrical interference while maintaining effective monitoring coverage.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent extracts the monitoring function to static working conditions, separating the detection process from the noisy operational environment. By performing measurements only when the vehicle is stationary and electrical loads are minimized, the system extracts clean data from the operational context without being contaminated by vehicle-mounted device interference.

Inventive Principle:
Principle #2Taking out (Extraction)

3Measurement precision

If extensive data collection and computational analysis are performed, then accurate detection of micro-internal short circuits can be achieved, but the BMS with limited computational capabilities cannot process the data effectively

Engineering Contradiction:
Improvemicro-internal short circuit detection accuracyVSAvoidcomputational processing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies partial monitoring by focusing only on static working conditions rather than continuous monitoring. This selective approach collects sufficient data to detect micro-internal short circuits while generating a manageable dataset that the BMS can process with its limited computational resources, avoiding the need for extensive continuous data collection and analysis.

Inventive Principle:
Principle #16Partial or excessive action

4Productivity

If monitoring is performed in dynamic working conditions, then battery usage can be tracked, but the static battery changes difficult to be monitored and accurate monitoring results cannot be obtained

Engineering Contradiction:
Improvebattery usage trackingVSAvoidstatic battery change detection accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent utilizes periodic static working conditions that naturally occur during vehicle operation (parking, stops, charging) to perform monitoring. These periodic intervals provide the stable electrical environment needed for accurate self-discharge rate measurement, while the system maintains awareness of overall battery usage through continuous voltage tracking during dynamic phases.

Inventive Principle:
Principle #19Periodic action

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 accurate and efficient monitoring of micro-internal short circuits, reducing the risk of thermal runaway and improving safety by providing timely alarm handling and maintenance actions.

Implementation Method 1

performing self-discharge observation and calculating a self-discharge rate based on a cell voltage in electrical signal information of each cell after depolarization is completed

Methodology Applied
Scientific EffectSelf-discharge:

Data Source

PatentEP4113141B1Method, system and apparatus for monitoring short circuit in battery
Publication Date: 2025.06.18 NIO CO LTD
  • EP4113141B1 patent drawingFigure 1~2
  • EP4113141B1 patent drawingFigure 3~4
  • EP4113141B1 patent drawingFigure 5~6

AI summary

The disclosure provides a method and system for monitoring a battery short circuit and an apparatus. The method includes: receiving collected electrical signal information of all cells in each traction battery; performing self-discharge observation and calculating a self-discharge rate based on a cell voltage in electrical signal information of each cell after depolarization is completed, to determine whether there is an internal short circuit in a traction battery where the cell corresponding to the self-discharge rate is located; and triggering alarm handling for the internal short circuit in the traction battery based on a back-fed result that there is an internal short circuit in the traction battery. In this way, a problem of how to monitor a micro-internal short circuit in a traction battery in a good static working condition with accuracy and efficiency while taking operation into consideration is solved, data collection of a static battery and calculation based on big data records are implemented, and a calculation method is improved, thereby improving accuracy and efficiency of monitoring an internal short circuit in the traction battery while taking operation into account.