Capacity Of Lead-acid Batteries Research Articles

A critical review of using the Peukert equation for determining the remaining capacity of lead-acid and lithium-ion batteries

In many applications it is essential to predict the remaining capacity of a battery reliably, accurately and simply. Several existing techniques for predicting the remaining capacity of a lead-acid battery discharged with a variable current are based on variants of Peukert's empirical equation, which relates the available capacity to a constant discharge current. This paper presents a critical review of these techniques in the light of experimental tests that were carried out on two lead-acid commercial batteries. The relevance of these Peukert's equation based techniques to lithium-ion batteries is also discussed in the light of tests carried on a lithium-ion power battery. The basic conclusion of the paper is that Peukert's equation cannot be used to predict the state of charge of a battery accurately unless it is discharged at a constant current and constant temperature.

Lead-acid battery capacity in solar home systems—Field tests and experiences in Lundazi, Zambia

Batteries in solar home systems can cause problems and costs for the users and/or operators of the systems. In Zambia the Lundazi Energy Service Company (LESCO) operates 150 solar home systems on a fee for service basis. The aim of the study was to investigate how the capacity of lead-acid flat plate batteries had changed after one year of operation under real conditions. The results indicate that the batteries capacity has been significantly reduced in comparison to new unused batteries of the same type. Changes in battery management and maintenance, along with additional education of customers on correct use of SHS is advised in order to improve the life span of batteries in practical use.

00/03454 Understanding the mechanism by which bismuth improves lead-acid battery capacity

00/03454 Understanding the mechanism by which bismuth improves lead-acid battery capacity

Understanding the mechanism by which bismuth improves lead-acid battery capacity

To elucidate the mechanism by which bismuth enhances the capacity of valve-regulated lead-acid (VRLA) batteries, model experiments are performed on pulverized positive electrodes produced either from leady oxide, which contains virtually no bismuth (termed ‘Bi-free oxide’), or from Pasminco VRLA Refined™ oxide, which is of high purity and contains a specified amount (0.05 wt.%) of bismuth. The electrodes are compressed under a range of pressures (1.4 to 60 kPa). Below 40 kPa, the presence of bismuth increases the initial capacity. At all pressures, bismuth enhances the rate at which the capacity develops during cycling. Reconnection of the separated agglomerates of lead dioxide is the key factor in restoring the capacity of the pulverized electrode. Electron micrographs reveal that there are two essential types of contact in the positive material: (i) ‘micro-contact’ between individual irregular-shaped or individual needle-like crystals, to form the agglomerates; (ii) ‘macro-contact’ between individual agglomerates, to form the skeleton of the positive mass. Bismuth encourages the growth of fine needle-like crystals on the surface of the agglomerates. These crystals spread out and inter-weld to form ‘bridges’ between the agglomerates and, thereby, consolidate the porous mass of the electrode. This influence of bismuth on morphology is considered to be responsible for the demonstrated improvements in capacity performance.

Predicting lead–acid battery electrode performance using finite difference equations

This paper presents a computer model that includes the effects of paste conductivity and electrolyte diffusion on the capacity of lead acid batteries. The model simulates the discharge of a complete cell by using finite difference equations to represent electrolyte diffusion in the positive and negative plates as well as in the space between them. The critical volume fraction relates the maximum amount of active material that can be reacted before the paste conductivity limits the reaction. The model uses this and other physical parameters to predict cell capacity. These predictions are then compared with experimental results.

Improving photovoltaic system sizing by using electrolyte circulation in the lead-acid batteries

Lead-acid batteries are, between all types of batteries, the most used today as storage systems for photovoltaic applications. The sizing of the lead-acid batteries is based on some external parameters, solar irradiation and load consumption, and some battery characteristics, charge capacity and efficiency, depth of discharge, operating voltage, and ageing effects. The improvement of any of these parameters will result in an improvement of the sizing of the lead-acid battery and, consequently, of the sizing of the photovoltaic array. We have studied in this paper the influence of the improved capacity of lead-acid batteries with electrolyte circulation onto the sizing of the lead-acid battery and the PV array. The experimental results have shown that the lead-acid battery capacity can be improved as much as 20% if electrolyte circulation is used. The improvement results in a reduction of up to 30% in the size of the battery if combined with the improvement in the reduction of the battery capacity due to annual cycling and ageing, another beneficial effect of the electrolyte circulation. The reduction of size is extended to the PV array which is affected not only by the above mentioned effects, but also by the higher charge efficiency of the electrolyte circulation battery. The reduction in sizing the PV array can be as much as 41% for the most exigent operating conditions, deep depth of discharge and high discharge rate. The use of an electrolyte circulation system is especially useful in lead-acid batteries for PV systems which must operate at very deep cycling and require a minimum size of the battery block.

Understanding and defeating the physical mechanisms limiting the capacity of lead-acid batteries

In this paper, we summarize previous work [1–6] that helped to establish the physical processes limiting the capacity of lead-acid batteries. Jon diffusion and paste conductivity are the dominate processes that limit capacity over a wide range of discharge rates. A model which includes both these processes was developed and used to understand the role of additives in the positive paste. With a basic understanding of the physical mechanisms limiting capacity and equipped with the model, we are pursuing designs for dramatically improving the capacity of lead-acid batteries. Some of these designs will be discussed in this paper.

Determination of lead-acid battery capacity via mathematical modeling techniques

The evaluation of the ampere-hour capacity of a lead-acid battery using a mathematical modeling technique is presented. The battery model was used to simulate a battery cycle at different temperatures, at different rates of charge and discharge, and at different end voltages to determine how the battery parameter of ampere-hour capacity was affected. The parameter obtained from the model simulation was compared with experimental results for verification. It is shown that the mathematical model accurately depicts ampere-hour capacity under various operating conditions.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>