State of charge

About: State of charge is a research topic. Over the lifetime, 12013 publications have been published within this topic receiving 201419 citations. The topic is also known as: SoC & SOC.

Method for determining state of charge of a battery by measuring its open circuit voltage

Abstract: A method (Fig. 1) for determining the state of charge (SOC) of a battery by measuring its open circuit voltage (OCV) either with the battery in a fully rested state of chemical and electrical equilibrium or an active state during a period in which the battery settles after charge or discharge is stopped. A first type algorithm (Fig. 4) is developed to correlate the OCV in a fully rested condition (OCVREST) to the state of charge at which that measurement is taken. A second type algorithm is developed that predicts a final settling OCV of a battery (OCVPRED), based on the set of parameters of OCV, rate of change of OCV, and battery case temperature, acquired during the settling period of a battery not at rest. To determine the SOC of a battery being tested that is in the fully settled state the measured OCVREST is applied to the first type algorithm (Fig. 4). To determine the SOC of a battery that has not fully settled, the data of the OCV, rate of change of OCV and battery temperature is applied to a second type algorithm to determine OCVPRED and the OCVPRED value is used in the first type algorithm to determine SOC.

Numerical investigation on thermal behaviour of 5 × 5 cell configured battery pack using phase change material and fin structure layout

Abstract: Lithium-ion battery, the indispensable part of electric vehicles or hybrid electric vehicles because of their high energy capacity and power density but usually suffer from a high temperature rise due to heat generation within a battery. This heat generation is mainly a function of the state of charge and charge/discharge rate. A passive technique like phase change material cooling has receiving a wide recognition due to its high latent heat, compact nature, and lightweight without consuming any external power. In this article, the thermal performance of the battery module containing 5 × 5 lithium-ion battery arranged in series and parallel is evaluated using phase change material. Initially, the performance of a battery module is examined with and without PCM at different discharge rate. It was found that more heat is accumulated at the interior portion of the battery pack due to mutual heating and low heat dissipation ability of PCM at a higher discharge rate. To improve such interior heat dissipation, different fin structure layout like Type I, Type II, Type III and Type IV are proposed and analysed using maximum temperature and average temperature distribution in a PCM based battery pack. It reveals that fin structure layout of Type III minimizes heat accumulation at the interior with adequate melting time among all. Furthermore, charge and discharge characteristics are investigated at different rate using rest time, convection effect and fin structure. The results indicated that use of rest time and increasing convection effect not only reduces maximum temperature but also recover melting fraction of PCM. Results also illustrate that the thermal performance of PCM based battery pack slightly get affected with the use of fin structure at lower convection, but decreases the maximum temperature by 8.17% at higher convection. Heat source a function of the state of charge and charge/discharge rate are given using Ansys-Fluent code and results are reported in the form of maximum temperature, average temperature and melting fraction.

Electric hair curling iron with rechargeable battery power supply

Abstract: An electrically heated hair curling iron includes a sheet-shaped heater with electrodes affixed to an electrically resistive layer, wrapped around an elongated cylindrical support, and capable of being rapidly heated and maintained hot by electric current available from a rechargeable storage battery. The resistive layer has a positive temperature coefficient of resistance so that its temperature is self limiting. The storage battery is contained in a handle attached to the cylindrical support, and a battery charger is disclosed which comes into electrical contact with the battery when the handle is inserted in a cavity located in the battery charger. An elongated longitudinal clip is used to retain the hair in contact with the heater; a removable cap protects the heater and clip when the iron is not in use, and also engages a switch which ensures that the iron does not remain on. The charger and the curling iron are each provided with an LED to indicate operation of the charger and state of charge of the battery, respectively.

Degradation Behavior of Lithium-Ion Batteries During Calendar Ageing—The Case of the Internal Resistance Increase

Abstract: Lithium-ion batteries are regarded as the key energy storage technology for both e-mobility and stationary renewable energy storage applications. Nevertheless, Lithium-ion batteries are complex energy storage devices, which are characterized by a complex degradation behavior, which affects both their capacity and internal resistance. This paper investigates, based on extended laboratory calendar ageing tests, the degradation of the internal resistance of a lithium-ion battery. The dependence of the internal resistance increase on the temperature and state-of-charge level has been extensive studied and quantified. Based on the obtained laboratory results, an accurate semiempirical lifetime model, which is able to predict with high accuracy the internal resistance increase of the lithium-ion battery over a wide temperature range and for all state-of-charge levels, was proposed and validated.