Battery State-of-Health Monitoring via Ohmic Normalization

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Solution Overview

Problem

Existing battery monitoring systems struggle to accurately determine the state-of-health of battery cells and containers over extended temperature ranges, especially in non-climate controlled environments, as ohmic value measurements are significantly affected by temperature variations, making it difficult to distinguish between temperature-induced changes and health-related changes in battery performance.

Innovation Solution

A method and system that utilize temperature data to estimate the electrolyte temperature of battery cells and containers, normalizing ohmic value measurements to a standardized temperature (e.g., 77°F) using algorithms and temperature coefficients, allowing for accurate state-of-health determination by comparing normalized ohmic values to predetermined thresholds, which can also account for age and specific gravity of the batteries.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If ohmic value measurements are taken at varying temperatures in non-climate controlled environments, then the monitoring system can operate in extended temperature ranges, but the measurement precision deteriorates due to temperature-dependent ohmic value changes

Engineering Contradiction:

Improveoperating temperature rangeVSAvoidstate-of-health determination accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent applies parameter changes by normalizing ohmic value measurements to a reference temperature using temperature coefficients. The system adjusts the measured ohmic value based on the actual temperature and a predetermined temperature coefficient to calculate a normalized ohmic value that represents what the measurement would be at the reference temperature (77°F), thereby eliminating temperature-induced measurement errors while maintaining operation across extended temperature ranges

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses temperature coefficients as an intermediary element to mediate between actual temperature variations and ohmic value measurements. These coefficients serve as a conversion factor that translates temperature differences into corresponding ohmic value adjustments, allowing the system to compensate for temperature effects without requiring climate control

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If temperature compensation algorithms are implemented to normalize ohmic values, then the state-of-health measurement accuracy is improved, but the device complexity increases due to additional calculations and parameters

Engineering Contradiction:

Improvestate-of-health determination accuracyVSAvoidnormalization algorithm complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by pre-determining temperature coefficients during a break-in period (first time period) before normal operation. These coefficients are stored and reused during subsequent monitoring, eliminating the need for real-time coefficient calculation and reducing the computational complexity during actual state-of-health assessments

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements a simplified normalization approach that uses linear compensation with predetermined temperature coefficients rather than complex multi-parameter models. This partial action provides sufficient accuracy for practical applications while keeping the algorithm computationally efficient and easy to implement

Inventive Principle:

Principle #16Partial or excessive 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 reliable state-of-health monitoring of battery cells and containers across varying temperatures, ensuring timely detection of failing cells and reducing the risk of unexpected failures by maintaining accuracy equivalent to measurements taken at a normalized temperature.

Implementation Method 1

Ohmic value is known to be temperature dependent. When a battery cell starts to fail the internal resistance of the battery cell increases.

Methodology Applied

Scientific EffectTemperature dependence of ohmic value: Electrical Resistance

Data Source

PatentUS10712396B2Methods, systems, and devices for monitoring state-of-health of a battery system operating over an extended temperature range

Publication Date: 2020.07.14 PARAMETER LLC

AI summary

Disclosed herein are methods, systems, and devices for determining a state-of-health (SOH) of battery systems over extended temperatures. According to one embodiment, a computer implemented method includes (1) receiving measured temperature data and measured ohmic value data associated with a battery cell; (2) determining an estimated battery cell electrolyte temperature based on the measured temperature data; (3) determining a normalized ohmic value based on the measured ohmic value data and the estimated battery cell electrolyte temperature, wherein the normalized ohmic value is related to a normalized temperature; and (4) transmitting, to at least one of a graphical user interface (GUI) and a battery log, an indication of an SOH of the battery cell based upon the normalized ohmic value being greater than a normalized maximum ohmic value, wherein the normalized maximum ohmic value is indicative of an abnormal SOH of the battery cell for the normalized temperature.