VRLA Research Articles

Pb-Ca-Sn-Ba Grid Alloys for Valve-Regulated Lead Acid Batteries

The effect of barium additives on the process of anodic corrosion of lead-tin-calcium alloys in a 4.8 М sulfuric acid solution was studied. Cyclic voltammetry, impedance spectroscopy, weight loss measurements and scanning electronic microscope analysis have allowed exploring the oxidation process and characterizing the formed corrosion layer. According to our results, barium introduction into lead-tin-calcium alloys increases their hardness, reduces their electrochemical activity, and improves their corrosion stability. Reduction of the calcium content in the alloy can be compensated by adding barium. Barium dopation at lead-tin-calcium alloys decreases the resistance of the oxide layer formed on the grid surface, in a deeply discharged state, and raises its resistance during floating conditions and at a charged state of the positive electrode.

Влияние давления поджима на структурные характеристики сепарационных материалов и эффективность ионизации кислорода в электродном блоке свинцово-кислотного аккумулятора

In this article was studied pressure influence in the electrode block of the model of the lead-acid accumulator on the most important physical properties (a specific surface, pore size distribution, compression properties, speed of capillary lifting of electrolyte) of absorbent glass mat separators of the trademarks «Hollingsworth» (USA) and "Bernard Dumas"(France) and on efficiency of an oxygen cycle. It is shown that the highest compression properties separators with a high specific surface (7-10 m2/g) possess. The increase of pressure in the electrode block conducts to pores size redistribution towards decrease in a share of a pore with a radius of 10-15 microns and increase in a share of smaller pore with radius of 1-5 microns. Observed reduction of a share of a large pore explains decrease in height and speed of lifting of electrolyte with higher pressure in the electrode block. The increase of pressure in the electrode block to 50 kPa leads to decrease oxygen ionization rate on a lead electrode.

상용자동차용 직·병렬 AGM 배터리 시스템의 충·방전 거동 모델링

최근 전 세계가 환경문제와 에너지 자원 고갈 문제에 대해 관심을 집중하고 있다. 이런 문제들을 해결하기 위한 여러 가지 방법들 중 하나가 하이브리드자동차(HEVs)이다. 그래서 하이브리드자동차 기술에 대한 사람들의 관심이 높아지고 있다. 하이브리드 자동차의 에너지 저장 시스템의 후보들은 AGM 배터리, Ni-MH 배터리 및 리튬배터리 등이다. AGM 배터리는 상대적으로 낮은 가격, 높은 충전 효율, 낮은 자가 방전 및 높은 안전성 등이 장점이다. 상용자동차에 하이브리드 자동차 시스템을 적용하기 위해서는 4개의 AGM 배터리를 2개의 직렬과 2개의 병렬로 연결해야한다. 본 연구에서는 상용차용으로 사용될 직 병렬로 연결되어 있는 AGM 배터리 시스템의 충 방전 특성을 예측하기 위하여 AGM 배터리의 충 방전 모델링을 수행하였다. AGM 배터리의 충 방전 모델링을 위해 내부에서 일어나는 전기화학 반응, 전하 보전과 물질 보존 법칙을 통해 배터리의 지배방정식으로 세웠다. 모델링 결과의 정확성을 검증하기 위해 다양한 조건에서의 실험결과와 비교하였다. Recent in the world environmental issues and energy depletion problems have been received attention. One way to solve these problems is to use hybrid electric vehicles (HEVs). Therefore, the interest in HEV technology is higher than ever before. Viable candidates for the energy-storage systems in HEV applications may be absorbent glass mat (AGM) lead-acid, nickel-metal-hydride (Ni-MH) and rechargeable lithium batteries. The AGM battery has advantages in terms of relatively low cost, high charge efficiency, low self-discharge, low maintenance requirements and safety as compared to the other batteries. In order to implement HEV system in required more electric power commercial vehicles AGM batteries was connected to 2 series-2 parallels (2S2P). In this study, a one-dimensional modeling is carried-out to predict the behaviors of 2S2P AGM batteries system during charge and discharge. The model accounts for electrochemical reaction rates, charge conservation and mass transport. In order to validate the model, modeling results are compared with the experimentally measured data in various conditions.

Effects of electrochemically active carbon and indium (III) oxide in negative plates on cycle performance of valve-regulated lead-acid batteries during high-rate partial-state-of-charge operation

In order to inhibit sulfation and hydrogen evolution of the negative plates and to prolong the cycle life of valve-regulated lead-acid batteries for hybrid-electric vehicles, electrochemically active carbon (EAC) and Indium (III) oxide (In2O3) are added into negative active materials of valve-regulated lead-acid batteries. The influences of EAC and In2O3 on the cycle performance of valve-regulated lead-acid batteries are investigated under high-rate partial-state-of-charge conditions. Experiment results indicate that addition of EAC in negative active materials can prolong the high-rate partial-state-of-charge cycle performance of valve-regulated lead-acid batteries, whilst it results in the accelerated evolution rate of hydrogen during charge process. It is also observed that EAC with an appropriate amount of In2O3 can effectively increase the overpotential of hydrogen evolution, which can not only produce the decreased hydrogen evolution rate and promote conversion of PbSO4 to Pb in capacity recovery process, but also prolong the high-rate partial-state-of-charge cycle life of valve-regulated lead-acid batteries. The battery added with 0.5% EAC and 0.02% In2O3 in negative active materials exhibits at least four times longer cycle life than that without In2O3.

Study of Thermal-Runaway in Batteries: II. The Main Sources of Heat Generation in Lead-Acid Batteries

Despite of the numerous research on thermal–runaway in valve regulated lead–acid batteries, its exact cause is not well known yet and it is not clear which physical phenomena contribute to thermal rise. To have a better understanding, the main sources of heat generation in lead–acid batteries are studied using the governing equations of battery dynamics derived in Part I. The governing equations including the conservation of energy are applied to different electrochemical reactions that take place during the overcharge of the battery. The reversible and irreversible heat sources of each reaction are determined separately. To investigate the heat generation contribution of each reaction, the governing equations are solved numerically using a two–dimensional thermal–electrochemical model. In this investigation, each term in the energy equation is calculated quantitatively in order to realize its contribution to heat generation. The numerical results show that beside Joule heating, only irreversibility contributes to heat generation which in turn results into temperature rise and the reversible part has no contribution.

The testing of batteries linked to supercapacitors with electrochemical impedance spectroscopy: A comparison between Li-ion and valve regulated lead acid batteries

For electric vehicles, a supercapacitor can be coupled to the electrical system in order to increase and optimize the energy and power densities of the drive system during acceleration and regenerative breaking. This study looked at the charge acceptance and maximum discharge ability of a valve regulated lead acid (VRLA) and a Li-ion battery connected in parallel to supercapacitors. The test procedure evaluated the advantage of using a supercapacitor at a 2 F:1 Ah ratio with the battery types at various states of charge (SoC). The results showed that about 7% of extra charge was achieved over a 5-s test time for a Li-ion hybrid system at 20% SoC, whereas at the 80% SoC the additional capacity was approximately 16%. While for the VRLA battery hybrid system, an additional charge of up to 20% was achieved when the battery was at 80% SoC, with little or no benefit at the 20% SoC. The advantage of the supercapacitor in parallel with a VRLA battery was noticeable on its discharge ability, where significant extra capacity was achieved for short periods of time for a battery at the 60% and 40% SoC when compared to the Li-ion hybrid system. The study also made use of Electrochemical Impedance Spectroscopy (EIS) with a suitable equivalent circuit model to explain, in particular, the internal resistance and capacitance differences observed between the different battery chemistries with and without a supercapacitor.

The application of spray drying method in valve-regulated lead-acid battery

Spray drying method has been successfully applied to the field of lead-acid batteries. Lead powder/carbon black composite can be obtained by spray drying and subsequent calcination process. Glucose is added to increase the adhesion of carbon black and lead powder. The morphology changes before and after calcination are examined by FE-SEM. The composite negative material can enable the sum of discharge capacity increased by 8.27% from 4374.855 Ah to 4736.706 Ah at a discharge current of 25 A after 66 cycles. And the charge acceptance of the test cell also can be obviously enhanced.

Identification and remediation of sulfation in lead-acid batteries using cell voltage and pressure sensing

The operating environment, manufacturing variability, and use can cause different degradation mechanisms to dominate capacity loss inside valve regulated lead-acid (VRLA) batteries. If an aging mechanism for each cell can be identified in real-time, cell usage can be adjusted by the battery management system to optimize the performance and service life of the energy storage system. In this paper, the cell voltage and pressure of new and dead VRLA batteries are monitored during testing to determine the cause of death of the cells. The new cells have fairly uniform performance with limited signs of degradation while the cells in the dead battery have widely ranging performance, especially at the end of discharge and charge. Based on the measurement data, it appears that one cell died from sulfation and another three died of dehydration. The battery capacity is mainly dictated by the sulfated cell. A desulfation charging control scheme with pressure feedback is designed to break up hard sulfate and recover capacity while minimizing water loss by using low current charging. The capacity of the cell is recovered by 41% with minimal water loss, demonstrating the effectiveness of the desulfation charge controller.

Substrate integrated Lead-Carbon hybrid ultracapacitor with flooded, absorbent glass mat and silica-gel electrolyte configurations

Lead-Carbon hybrid ultracapacitors (Pb-C HUCs) with flooded, absorbent-glass-mat (AGM) and silica-gel sulphuric acid electrolyte configurations are developed and performance tested. Pb-C HUCs comprise substrate-integrated PbO2 (SI-PbO2) as positive electrodes and high surface-area carbon with graphite-sheet substrate as negative electrodes. The electrode and silica-gel electrolyte materials are characterized by XRD, XPS, SEM, TEM, Rheometry, BET surface area, and FTIR spectroscopy in conjunction with electrochemistry. Electrochemical performance of SI-PbO2 and carbon electrodes is studied using cyclic voltammetry with constant-current charge and discharge techniques by assembling symmetric electrical-double-layer capacitors and hybrid Pb-C HUCs with a dynamic Pb(porous)/PbSO4 reference electrode. The specific capacitance values for 2 V Pb-C HUCs are found to be 166 F/g, 102 F/g and 152 F/g with a faradaic efficiency of 98%, 92% and 88% for flooded, AGM and gel configurations, respectively.

The Analysis of the Emission from SUV Vehicle Fitted with Ci Engine and Start-Stop System / Analiza Emisyjności Pojazdu Kategorii Suv Z Silnikiem Zs Wyposażonego W System Start-Stop

Abstract The article presents the results of emission test Sport Utility Vehicle (SUV) with diesel engine, equipped with start-stop system. Measurements was carried out in on-road conditions in urban traffic. Article presents a method of work implemented start-stop system, and the characteristics of the implemented battery Absorbent Glass Mat (AGM). Analysis of the results allowed to indicate the effectiveness of the system and its impact on emission per second. In addition was determined road emission and fuel consumption from performed test. For measurement was used mobile gas analyser SEMTECH DS included in Portable Emissions Measurement Systems (PEMS)

Mild HEV Performance at Micro Hybrid Cost - A Low Voltage Lead-Acid Approach

The Advanced Lead Acid Battery Consortium (ALABC) has since 2000 been demonstrating valve-regulated lead-acid (VRLA) batteries in hybrid electric vehicles and has shown that advanced designs can cope with this duty cycle with good reliability (1). This demonstration work has been done by converting existing vehicles and thus all work to date has utilized Japanese mild hybrids. The European market is coming at hybridization from a different direction, with the introduction of low-cost micro-hybrid stop/start systems, such as the BMW EfficientDynamics (2), in order to meet CO2 regulations. Recently Controlled Power Technologies (CPT) has been promoting an alternative way of achieving mild hybrid performance (3), which would meet projected CO2 regulations, at a fraction of the cost of the current Japanese approach. This new system would operate with advanced VRLA batteries at 12V or 48V and provides an opportunity for lead-acid to be at the leading edge of hybrid technology.

Carbon Corrosion Mechanisms in Batteries during High-Rate, Partial State-of-Charge Cycling

Battery cycling profiles in hybrid electric vehicles have high currents both during charging, when the vehicle brakes are applied, and during discharging, when the vehicle accelerates. Cycle life in these high-rate, partial-state-of-charge (HRPSoC) applications is improved by adding conductive carbons with high surface areas to the negative active material. During charge, however, carbon can be oxidized by water to form soluble carbon monoxides such as formic acid. Further oxidation produces gaseous carbon dioxide at the positive electrode. As the internal cell pressure increases, it may force the vents open to release the carbon dioxide and other gases in the battery. Fortunately carbon dioxide formation is slowed by limited transport of soluble carbons from the negative to the positive plates. The valve-regulated lead-acid (VRLA) battery life is extended by carbon additions to the negative plate, but the ultimate cause of failure may become cell dry-out.

Researches on current distribution and plate conductivity of valve-regulated lead-acid batteries

A cell with tall plates was simulated by two cells and the controlled voltage with time was successfully used to measure the response current–time curves. It indicates that the current in the upper part of the plate is much higher than that in the lower part in early stage of the discharge, but in late stage, it is reversed, especially at high discharge rates. The upper part of the plate has higher capacity and deeper depth of discharge (DOD) so that the active mass degrades and sheds more quickly in cyclic applications. In the initial discharge, the lead sulfate formed at positive plates produces the internal stress and enhances the electric connection among the active mass particles. But the positive active mass only contributes a little to the conductivity of plates. The negative active mass with a bit shrinking but no passivation has better conductivity than the expanded active mass. The higher ohmic polarization of the active mass appears at higher discharge rates, in the upper part of the plates, in the late stage of the discharge, in aged battery, especially for negative plates.

Modelling of VRLA batteries over operational temperature range using Pseudo Random Binary Sequences

This paper continues previous work concerning the use of maximum length sequences within parameter estimation for batteries. Using the familiar Randles’ model batteries are examined over typical operational temperatures for variations in readily identifiable equivalent circuit parameters, using previously identified methods [1]. This analysis is used to present characteristics which can be subsequently used to inform the design of an online State-of-Charge (SoC) and State-of-Health (SoH) system for these batteries.

Experimental Investigation of H 2 Generator and PEM Fuel Cell as a Remote Area Back-Up Power

Abstract A reliable power is paramount and loss of power to communication equipment can mean loss of service to customers and loss of millions of dollars to companies. When the grid power is unavailable in remote areas there are variety of back-up electrical power systems like valve-regulated lead acid (VRLA) battery systems, engine-generator sets, ultra capacitors, flywheels, and new battery technologies that strive to provide back-up power. Hydrogen Energy and fuel cell technology compete with traditional technologies meeting back-up power requirements in stationary applications. Recent collaboration between Victoria University, Sustainable Energy Fuel Cells Australia (SEFCA) and Acta Energy has resulted in thorough laboratory testing for H 2 generation and data compilation of fuel cells in a back-up power operation in Power Systems Research Laboratory at Victoria University. The authors of this paper suggests that the use of EL100 H 2 generator and T-1000 1.2 kW PEMFC Power Generation System is capable to compete with traditional technologies to offer back-up power when there is no base load or PV or wind power. This paper presents the planning of laboratory testing, analysis and evaluation of the laboratory results. This paper also highlights the benefits of PEMFC system, EL100 H 2 generator and ReliOn's T-1000 PEMFC system. Currently it is expensive to run distance trucks requiring several site visits per year in order to refill the diesel or even carrying H 2 bottles to a rural site. This system generates H 2 on-site and can be implemented as a back-up power in telecommunication system like the Australian National Broadband Network (NBN) where there will be need for reliable back-up power supply since NBN will be rolling out several hundred points of presence (POP's).

Determination of regression functions for the charging and discharging processes of valve regulated lead-acid batteries

Abstract: Following the deep discharge of the valve-regulated lead-acid batteries of the type AGM SVT 300, using the ten-hour-discharge current, charging of the batteries with the variable current was performed. In accordance with the obtained results, exponential and polynomial functions for approximation of the specified processes were analyzed. The main evaluation instrument for a quality of the implemented approximations was the adjusted coefficient of determination, R^2. It was perceived that the battery discharge process may be successfully approximated both with exponential and the second order polynomial function. On all the analyzed occasions values of the adjusted coefficient of determination were greater than 0.995. Charging process of the deeply discharged battery was successfully approximated with the exponential function, with the measured values of the adjusted coefficient of determination being nearly 0.95. Beside the high measured values of the adjusted coefficient of determination, polynomial approximations of the second and third order did not provide satisfactory results regarding the interpolation of the battery charging characteristics. A possibility for a practical implementation of the procured regression functions in uninterruptible power supply systems was described.

Структурные характеристики абсорбтивно-стеклянных сепараторов и их влияние на эффективность ионизации кислорода в макетах свинцово-кислотных аккумуляторов

The most important structural and physicomechanical properties of absorbent glass mat separators «Hollingswoth and Vose», «Bernard Dumas», «BMSK AT Nippon» intended for lead-acid battery (LAB) are studied. It is shown that on pore size distribution strong influence puts the enclosed pressure: at compression 50 kPa there is a considerable reduction of the size of a pore. However for the separation material «BMSK AT Nippon» the share of pores with radius from 5 to 10 microns is much higher, than for the separation materials «Hollingswoth and Vose» and «Bernard Dumas». Studying of process of oxygen absorption on negative an electrode in the LAB models showed that most effectively process of absorption of oxygen occurs in the LAB models to the separation material «BMSK AT Nippon».

Lead-Acid Battery Model Under Discharge With a Fast Splitting Method

A mathematical model of a valve-regulated lead-acid battery under discharge is presented as simplified from a standard electrodynamics model. This nonlinear reaction-diffusion model of a battery cell is solved using an operator splitting method to quickly and accurately simulate sulfuric acid concentration. This splitting method incorporates one-sided approximation schemes to preserve continuity over material interfaces encompassing discontinuous parameters. Numerical results are compared with measured data by calculating battery voltage from modeled acid concentration as derived from the Nernst equation.

On Chip Kalman Filtering Strategy-Based for VRLA Battery Control Unit

Based on existing understanding of residual capacity, the paper adopts Kalman filtering method on SOC estimation. The battery control unit(BCU) includes voltage, current and temperature sampling module. Due to Lead-Acid battery charging and discharging are a complex electrochemical process, we suggest a non-linear least squares regression method (NLLSRM) on open circuit voltage (OCV) method is proposed to aim at Lead-Acid battery. At the same time, a detailed hardware circuit schemes transfer module and on chip embedded Kalman filter method are employed. Moreover, A Local Interconnect Network (LIN) Bus Communication Technology is applied to communicate to Electronic Control Unit (ECU). Validation experimental results show that the proposed Lead-Acid BCU is high credible and the state of charge (SOC) estimation average relative error is about 3%.

Comparative evaluation of different power management strategies of a stand-alone PV/Wind/PEMFC hybrid power system

This study presents different power management strategies of a stand-alone hybrid power system. The system consists of three power generation systems, photovoltaic (PV) panels, a wind turbine and a proton exchange membrane fuel cell (PEMFC). PV and wind turbine is the main supply for the system, and the fuel cell performs as a backup power source. Therefore, continuous energy supply needs energy storing devices. In this proposed hybrid system, gel batteries are used. The state of charge ( SOC), charge-discharge currents are affecting the battery energy efficiency. In this study, the battery energy efficiency is evaluated with three different power management strategies. The control algorithm is using Matlab-Simulink®.