System for Identifying Optimal Transition Points Between Charge Tiers of a Battery Pack

This publication describes systems and techniques for identifying transition points between charge tiers of a battery pack in a portable electronic device. Portable electronic devices, including smartphones, are often powered by rechargeable lithium-ion or lithium-ion polymer battery packs. Electronic devices charge a battery pack using a series of constant-current stages and constant-voltage stages. It is generally desirable to remain in a constant-current stage as long as possible, but identifying the optimal transition point from constant-current charging to constant-voltage charging usually requires specialized hardware components that increase the cost of the electronic device. This publication discloses charging systems and techniques to accurately determine the transition point between charging states without additional or specialized hardware. The disclosed systems and techniques also provide information about the state-of-health and impedance of a battery pack

Peak shaving through battery storage for low-voltage enterprises with peak demand pricing

The renewable energy transition has introduced new electricity tariff structures. With the increased penetration of photovoltaic and wind power systems, users are being charged more for their peak demand. Consequently, peak shaving has gained attention in recent years. In this paper, we investigated the potential of peak shaving through battery storage. The analyzed system comprises a battery, a load and the grid but no renewable energy sources. The study is based on 40 load profiles of low-voltage users, located in Belgium, for the period 1 January 2014, 00:00-31 December 2016, 23:45, at 15 min resolution, with peak demand pricing. For each user, we studied the peak load reduction achievable by batteries of varying energy capacities (kWh), ranging from 0.1 to 10 times the mean power (kW). The results show that for 75% of the users, the peak reduction stays below 44% when the battery capacity is 10 times the mean power. Furthermore, for 75% of the users the battery remains idle for at least 80% of the time; consequently, the battery could possibly provide other services as well if the peak occurrence is sufficiently predictable. From an economic perspective, peak shaving looks interesting for capacity invoiced end users in Belgium, under the current battery capex and electricity prices (without Time-of-Use (ToU) dependency)

Minimizing Running Costs in Consumption Systems

A standard approach to optimizing long-run running costs of discrete systems is based on minimizing the mean-payoff, i.e., the long-run average amount of resources ("energy") consumed per transition. However, this approach inherently assumes that the energy source has an unbounded capacity, which is not always realistic. For example, an autonomous robotic device has a battery of finite capacity that has to be recharged periodically, and the total amount of energy consumed between two successive charging cycles is bounded by the capacity. Hence, a controller minimizing the mean-payoff must obey this restriction. In this paper we study the controller synthesis problem for consumption systems with a finite battery capacity, where the task of the controller is to minimize the mean-payoff while preserving the functionality of the system encoded by a given linear-time property. We show that an optimal controller always exists, and it may either need only finite memory or require infinite memory (it is decidable in polynomial time which of the two cases holds). Further, we show how to compute an effective description of an optimal controller in polynomial time. Finally, we consider the limit values achievable by larger and larger battery capacity, show that these values are computable in polynomial time, and we also analyze the corresponding rate of convergence. To the best of our knowledge, these are the first results about optimizing the long-run running costs in systems with bounded energy stores.Comment: 32 pages, corrections of typos and minor omission

Analytically solvable many-body Rosen-Zener quantum battery

Quantum batteries are energy storage devices that satisfy quantum mechanical principles. How to obtain analytical solutions for quantum battery systems and achieve a full charging is a crucial element of the quantum battery. Here, we investigate the Rosen-Zener quantum battery with $N$ two-level systems, which includes atomic interactions and external driving field. The analytical solutions of the stored energy, changing power, energy quantum fluctuations, and von Neumann entropy are derived by employing the gauge transformation. We demonstrate that full charging process can be achieved when the external driving field strength and scanning period conforms to a quantitative relationship. The local maximum value of the final stored energy corresponds to the local minimum values of the final energy fluctuations and von Neumann entropy. Moreover, we find that the atomic interaction induces the quantum phase transition and the maximum stored energy of the quantum battery reaches the maximum value near the quantum phase transition point. Our result provides an insightful theoretical scheme to realize the efficient quantum battery.Comment: 9 pages,7 figure

Creating a circular EV battery value chain: End-of-life strategies and future perspective

The rapid uptake of electric vehicles (EVs) will be vital to decarbonise the transport sector and achieve climate change targets. However, this transition is leading to an increased demand for key battery materials and associated resource challenges and supply-chain risks. On the other hand, discarded EV batteries create business opportunities for second life and recycling. This study presents scenario-driven material flow analysis (MFA) to estimate the future volume of EV battery wastes to be potentially generated in Sweden and future demand for key battery materials, considering potential EV fleet, battery chemistry developments, and end-of-life strategies of EV batteries. Further, we combine MFA with a socio-technical approach to explore how different socio-technical developments will affect both EV battery flows and the underlying systems in the future. Recycling has the potential to reduce primary demand by 25–64% during 2040–2050 based on projected demand, meaning that waste streams could cover a considerable part of the future raw material demands. Second-use of EV batteries can promote circularity yet postpones recycling potentials. From a transition perspective, promoting recycling, second-life use of EV batteries and advanced battery technologies entail system disruption and transformational changes in technology, markets, business models, policy, and infrastructure and user practices. Demand for high-capacity batteries for grid decarbonisation and aviation applications may contribute to the emergence of niche battery technologies. Each scenario highlights the need for effective policy frameworks to foster a circular EV battery value chain

Influence of Efficiency, Aging and Charging Strategy on the Economic Viability and Dimensioning of Photovoltaic Home Storage Systems

PV in combination with Li-ion storage systems can make a major contribution to the energy transition. However, large-scale application will only take place when the systems are economically viable. The profitability of such a system is not only influenced by the investment costs and economic framework conditions, but also by the technical parameters of the storage systems. The paper presents a methodology for the simulation and sizing of PV home storage systems that takes into account the efficiency of the storage systems (AC, DC standby consumption and peripheral consumption, battery efficiency and inverter efficiency), the aging of the components (cyclic and calendar battery aging and PV degradation), and the intelligence of the charging strategy. The developed methodology can be applied to all regions. In this paper, a sensitivity analysis of the influence of the mentioned technical parameters on the dimensioning and profitability of a PV home storage is performed. The calculation is done for Germany. Especially, battery aging, battery inverter efficiency and a charging strategy to avoid calendar aging have a decisive influence. While optimization of most other technical parameters only leads to a cost reduction of 1–3%, more efficient inverters can save up to 5%. Even higher cost reductions (more than 20%) can only be achieved using batteries that age less, especially batteries that are less sensitive to calendar aging. In individual cases, a small improvement in the efficiency of the storage system can also lead to higher costs. This is for example the case when smaller batteries are combined with a large PV system and the battery is used more due to the higher efficiency. This results in faster ageing and thus earlier replacement of the battery. In addition, the paper includes a detailed literature overview on PV home storage system sizing and simulation