Hybrid Lead-Acid and Lithium-Ion Energy Storage System
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Solution Overview
Problem
Modern motor vehicles require advanced energy storage systems to manage increased demands from comfort and safety functions, necessitating improved energy storage devices that can handle frequent high-current discharge phases and optimize service life, which conventional systems struggle to address effectively.
Innovation Solution
A dual-energy storage system for motor vehicles, comprising a lead-acid battery and a lithium ion battery or super capacitor connected in parallel, with specific characteristic voltage and resistance curves that overlap and interact to minimize operational effort, allowing for efficient charging and discharging strategies without the need for complex electronics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional lead-acid battery is used as the sole energy store, then the system is simple and cost-effective, but it cannot handle frequent high-current discharge phases and has limited service life under increased electrical demands
Solution Approach 1:
The energy storage system is segmented into two distinct electrical energy stores: a first energy store (lead-acid battery) and a second energy store (lithium ion battery or super capacitor). Each energy store has different characteristic voltage and resistance curves, allowing them to serve different functions. The lead-acid battery handles steady-state operations and cold starts, while the lithium ion battery or super capacitor handles transient high-current demands, thereby extending the overall service life of the system without requiring complete system redesign
Solution Approach 2:
The patent utilizes the different voltage and resistance characteristics of the two energy stores by carefully selecting their operating ranges. The characteristic voltage curves are designed to overlap in a specific voltage value range, and the characteristic resistance curves have precisely one intersection point. This parameter-based differentiation allows the control system to automatically route current through the most appropriate energy store based on real-time electrical demands, optimizing service life without excessive complexity
2Use of energy by moving object
If the lead-acid battery is replaced with a lithium ion battery or super capacitor to handle high-current demands, then the energy availability improves, but the cost and complexity of the system increases
Solution Approach 1:
The patent merges a conventional lead-acid battery with a lithium ion battery or super capacitor in a hybrid configuration. This combination allows the system to leverage the cost-effectiveness and cold-start capability of the lead-acid battery while simultaneously benefiting from the high-power density and fast response of the lithium ion battery or super capacitor. The merging is achieved through parallel connection with coordinated control based on voltage and resistance characteristics, improving energy availability without fully replacing the cost-effective lead-acid component
Solution Approach 2:
The dual-energy store system provides multi-functionality: the first energy store (lead-acid) handles cold starts and steady-state operations, while the second energy store (lithium ion or super capacitor) handles transient high-current demands and regenerative braking. This universal approach allows a single system to perform multiple functions that would otherwise require separate systems, improving energy availability while managing cost and complexity through shared control infrastructure
3Reliability
If a dual-energy store system is implemented, then the service life and energy availability improve, but the control complexity and operational effort increase
Solution Approach 1:
The dual-energy store system operates with a high degree of autonomy through self-service mechanisms. The control system automatically determines which energy store should charge or discharge based on real-time monitoring of voltage and resistance characteristics, without requiring complex external control or manual intervention. The system uses the overlapping voltage curves and intersection point of resistance curves as natural decision boundaries, allowing the energy stores to essentially self-regulate their operation based on electrical demands and charge states
Solution Approach 2:
The system implements continuous feedback monitoring of the voltage and resistance characteristics of both energy stores. By tracking the characteristic voltage curves and resistance curves, the control system receives real-time feedback on the charge state and operational status of each energy store. This feedback enables automatic adjustment of charging and discharging operations, optimizing service life and energy availability while keeping control complexity manageable through rule-based decision logic derived from the characteristic curves
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 configuration optimizes the service life of the energy storage devices, reduces technical effort in operation, and enhances the availability of comfort functions by enabling efficient energy recovery and stabilization of the vehicle electrical system, while minimizing costs and maintaining the benefits of lead-acid batteries like cold start capability.
Implementation Method 1
a first electrical energy store, which is characterized by a first characteristic voltage curve defining the open-circuit voltage of the first electrical energy store depending on the relative charge state of the energy store
Data Source
AI summary
A motor vehicle energy storage device includes a first electrical energy store characterized by a first characteristic voltage curve defining the open-circuit voltage of the first energy store depending on the relative charge state and by a first characteristic resistance curve defining the internal resistance of the first energy store relevant for a charge process of the energy store, and a second electrical energy store connected in parallel and characterized by a second characteristic voltage curve defining the open-circuit voltage of the second energy store depending on the relative charge state and by a second characteristic resistance curve defining the internal resistance relevant for a charge process of the second energy store. The voltage value ranges covered by the first characteristic voltage curve and the second characteristic voltage curve partially overlap, and the first and second characteristic resistance curves and the second characteristic resistance curve have exactly one intersecting point.