Stationary Battery State of Charge Management
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Solution Overview
Problem
The operational lifetime and cycle life of stationary rechargeable batteries, particularly Li-ion technologies, are degraded by storage at full state of charge, leading to increased costs due to frequent replacements and high per-cycle costs in applications like load leveling.
Innovation Solution
A flexible management system that determines active and inactive energy consumption periods for energy storage devices, operating them in usage mode during active periods and storage mode during inactive periods, with a controller adjusting the state of charge to extend lifetime and reduce costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the energy storage device is stored at full state of charge, then the energy availability is maximized, but the operational lifetime is degraded
Solution Approach 1:
The patent implements dynamic state of charge management that adjusts the charging level based on whether the system is in active or inactive period. During inactive periods, the state of charge is maintained at a reduced level to extend battery lifetime, while during active periods, the state of charge is restored to full to ensure energy availability. This dynamic adjustment resolves the contradiction between maintaining high energy availability and extending operational lifetime.
Solution Approach 2:
The patent changes the state of charge parameter based on operational conditions. By transitioning between different state of charge levels (full charge during active periods, reduced charge during inactive periods), the system optimizes both energy availability and battery lifetime, resolving the technical contradiction between these two parameters.
2Power
If the energy storage device operates in usage mode during active periods, then the energy delivery capability is maximized, but the battery degradation increases
Solution Approach 1:
The patent implements periodic operation modes where the energy storage device alternates between usage mode during active periods and storage mode during inactive periods. This periodic cycling allows the battery to deliver full power when needed while resting and recovering during inactive periods, reducing cumulative degradation and maintaining battery health over time.
Solution Approach 2:
The patent performs preliminary charging to full state of charge before active periods begin, ensuring maximum energy delivery capability is available when needed. During inactive periods, the battery is allowed to rest at a reduced state of charge, which preliminarily reduces stress on the battery cells and prevents excessive degradation from continuous high-state-of-charge operation.
Data Source
AI summary
A flexible management system and method for efficiently operating energy storage devices to extend the lifetime and decrease costs includes (a) determining an active energy consumption period for the energy storage device; (b) determining an inactive energy consumption period for the energy storage device; (c) operating the energy storage device in a usage mode during the active energy consumption period; and (d) operating the energy storage device in a storage mode during the inactive energy consumption period.