» Advanced Battery Storage System

A review of state-of-charge indication of batteries by means of a.c. impedance measurements

arjun — Fri, 07 Nov 2008 14:51:56 +0000

Abstract A non-destructive estimation of the state-of-charge SoC. of batteries facilitates optimum utilization of the battery for a given application, as well as evaluation of its state-of-health. Among various methods, a.c. impedance spectroscopy over a wide range of frequencies provides a variety of parameters which are functions of the SoC of a given battery. These parameters and their variation with SoC depend on the type of battery and on the experimental conditions. The impedance data of sealed commercial cells are rather tedious to analyze since the results are generally the combined parameters of both the positive and the negative electrodes. Separation of the parameters which correspond to the individual electrodes involves assumptions, the validity of which is open to read more

A note on maximum work from an electric battery model

arjun — Fri, 07 Nov 2008 10:49:43 +0000

Abstract The maximum work from an electric battery in a finite time interval tC derived in a recent article in this journal is unreasonable. The reason is discussed in detail and the genuine maximum work is given. This shows that the result derived in the recent article is suitable only in the case tC→infinite.The maximum work from an electric battery in a finite time interval 0→tC was derived in a recent article in this journal [1]. It relied on a simple battery model as shown in Fig. 1. The non dimensionalized maximum work output derived by Bejan and Dan [1] is given by Download Share and Enjoy: read more

A New Method Of Establishing The State Of Charge Of Lead-Acid Batteries With Electrolyte Circulation

arjun — Fri, 07 Nov 2008 10:07:56 +0000

Abstract The proposed method of monitoring battery state-of-charge is based on electrolyte density measurements. It is reliable, applicable in all cases to batteries with a circulating electrolyte, and is very useful for high discharge rates. An empirical law, based on results obtained from different experiments has been developed. This law allows isolation of the accumulator state-ofcharge as a function of the maximum state-of-charge density at the test point and a proportionality constant, n. Download Share and Enjoy: read more

A new high rate,fast charge lead/acid battery

arjun — Fri, 07 Nov 2008 09:52:21 +0000

Abstract A new approach to the design of lead/acid batteries has been developed based upon the use of very thin,lead foil,current collectors and unique method for facilitating high current carrying capacity to and from external sources.The basic cell construction and the performance characteristics of valve regulated lead/acid design are described.Spiral wound cells with electrode/cast on strap configuration exhibit extremely high power output with a flat discharge voltage plateau at all normal currents.Conversely fast discharge of 10minutes,or less,to 100% capacity can be realized for the same reasons.Cycle life in deep discharge applications doesnot appear to be compromised by the thin foil used,as normal behavior is observed.Applications for this high power technology include read more

A new equation for the limiting capacity of the lead/acid cell

arjun — Fri, 07 Nov 2008 09:37:06 +0000

Abstract As an alternative to the empirical Peukert equation, whose validity is restricted to intermediate discharge rates, a new equation for the limiting capacity of the lead/acid cell is proposed, formally derived from an approximate closed form solution of a two finite compartment diffusion problem. The four parameters of the equation are evaluated through a non-linear least-squares method. The resulting capacity curve fits the typically undulating experimental data closely throughout their range. Download Share and Enjoy: read more

A model for simulating fast charging of lead/acid batteries

arjun — Fri, 07 Nov 2008 09:31:53 +0000

Abstract Among the various points which are discussed for the selection of batteries for electric vehicle applications, the possibility of fast charging is one of the most relevant. This is particularly true for the lead/acid battery which, at the present state of technology, must be charged at low rates to avoid serious shortening of its life. However, this type of battery can be successfully employed in electric vehicles for many advantageous features. The problems concerning some drawbacks of the lead/acid systems must be solved in order to improve its overall performance. In this paper we approached the problem of increasing the charging rate of the lead/acid battery by simulating, with a mathematical model, the discharge/charge conditions. Our aim was to derive useful information read more

A Method to Monitor Valve Regulated Lead Acid Cells

arjun — Fri, 07 Nov 2008 09:10:29 +0000

Abstract The individual electrode impedance parameters and internal resistance of industrial type 120Ah-valve regulated lead acid(VRLA)cells are obtained from galvanostatic nondestructive technique.The resistive components of the cell are found to be minimum at a state of charge(SOC)value of 0.5.The study reflects that the optimum performance of VRLA cells is achieved at SOC values between 0.2 and 0.8. Keywords: Valve-regulated lead acid cells; Impedance; State-of-charge Download Share and Enjoy: read more

A method for evaluating the performance for positive electrod grids of lead/acid batteries

arjun — Fri, 07 Nov 2008 08:57:53 +0000

Abstract For a battery plate to function satisfactorily,there must be a good contact at the interface between the grid and active material.This is because the adhesion of active material changes due to the state of interface between the grid and the active material.In this study the adhesion of active material is studied by the evaluation of grid surface.A grid with good adhesion has following characteristics(i)change in the rest potential is fast(ii)the lead sulphate membrane formed on the surface is thin and(iii)the change in potential during oxidation is slow.Good or bad adhesion of the active material can be judged using an evaluation method using the criteria.The annealing method of grid is evaluated using this method. Keywords:Lead/acid batteries;positive electrode read more

A High Reliability Battery Management System

arjun — Fri, 07 Nov 2008 08:45:30 +0000

Abstract Over a period of some 5 years Canadian Astronautics Limited (CAL) has developed a system to autonomously manage, and thus prolong the life of secondary storage batteries. During the development, the system has been aimed at the space vehicle application using nickel-cadmium batteries but it is expected to be able to enhance the life and performance of any rechargeable electrochemical couple. The system handles the cells of a battery individually and thus avoids the problems of over, and under, drive that inevitably occur in a battery of cells managed by an averaging system. This individual handling also allows cells to be totally bypassed m the event of failure, thus avoiding the losses associated with low capacity, partial short circuit, and the catastrophe of open circuit. read more

A battery ageing model used in standalone PV systems

arjun — Fri, 07 Nov 2008 08:33:22 +0000

Abstract The author present a new model for the aging of a Lead-Acid battery which is based on the initial model of the Shepherd.The proposed model allows to predict temporal variations of the Shepherd coefficients and to control the deterioration of battery parameters and performances.The model validation has been realised by the recursive least square algorithm by using long term measurements under several socialisation.This study will improve the storage section of stand alone photovoltaic systems and reduce the overloads and deep discharges. Keywords:Shepherd Model,Recursive Least Square Algorithm,Less Battery Storage System Download Share and Enjoy: read more