Li-Ion Battery Load Sharing Based on State-of-Health Ranking
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Solution Overview
Problem
Used lithium-ion batteries from electric vehicles, when repurposed, face challenges due to varying degradation trajectories, lower energy density, and shorter lifespan, making them inefficient for second-use applications like power generation systems, and recycling is costly and inefficient.
Innovation Solution
Implementing a battery management system that communicates load demands and state of health among batteries, prioritizes first-use batteries with higher health for primary load supply, sets discharge limits for second-use batteries, and optimizes electromechanical generator operation to extend battery and generator life while meeting load demands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If second use batteries are used in power generation systems, then cost is reduced and sustainability is improved, but reliability and lifespan are degraded due to lower energy density and varying degradation trajectories
Solution Approach 1:
The patent segments the battery fleet into first-use and second-use categories, with first-use batteries handling high-demand primary load supply and second-use batteries providing supplementary power. This segmentation allows each battery type to operate within its optimal performance envelope, extending overall system lifespan while maintaining cost-effectiveness.
Solution Approach 2:
The system dynamically adjusts battery engagement based on real-time state of health (SoH) monitoring and load conditions. The battery management system continuously ranks batteries by SoH and dynamically assigns roles, allowing second-use batteries to participate when conditions permit while protecting them from excessive stress that would degrade lifespan.
2Quantity of substance
If second use batteries with varying degradation trajectories are used, then quantity of batteries is optimized, but measurement precision and control accuracy are worsened due to difficulty in predicting individual battery behavior
Solution Approach 1:
The patent implements continuous feedback loops where battery management modules monitor state of health, state of charge, and performance metrics of each individual battery. This data feeds back to the central control system, which adjusts engagement strategies in real-time to account for varying degradation trajectories, maintaining precise control despite battery heterogeneity.
Solution Approach 2:
The system changes operational parameters for each battery based on its individual state of health and degradation characteristics. Second-use batteries receive adjusted discharge limits, charge rates, and engagement thresholds tailored to their specific condition, allowing accurate prediction and control of their unique degradation trajectories.
3Reliability
If first use batteries are prioritized for primary load supply, then reliability is improved, but device complexity increases due to need for sophisticated battery management and load sharing coordination
Solution Approach 1:
The patent designs battery management modules that perform multiple functions: state of health monitoring, state of charge tracking, discharge limit enforcement, and dynamic engagement control. This multi-functionality reduces the need for separate specialized systems, managing complexity while maintaining reliability through integrated first-use and second-use battery coordination.
4Duration of action of stationary object
If discharge limits are set for second use batteries, then lifespan is extended, but power output is reduced due to constrained current supply
Solution Approach 1:
The patent merges the output of second-use batteries with first-use batteries to meet total load demand. While second-use batteries have discharge limits that protect their lifespan, their combined power with first-use batteries achieves the required total output, resolving the contradiction between individual battery power constraints and system-level power requirements.
Data Source
AI summary
A method of managing second use batteries incudes communicating an external load demand to battery management modules (BMMs) of first use batteries and second use batteries; communicating, by each of the BMMs, the state of health (SoH) of the respective first or second use battery to the other BMMs; by the BMMs of the first use batteries with highest SoH, engaging the first use batteries to meet the external load demand, wherein the highest SoH is determined by the BMMs by ranking the SoH of each battery relative to the other batteries; and by the BMMs of the second use batteries, setting a discharge limit for each of the second use batteries based on the SoH of the respective second use battery, and controlling the second use batteries to supply currents not to exceed the discharge limits of the respective second use batteries to load-share with the first use batteries.