The document discusses impedance and conductance testing techniques for lead-acid batteries. Impedance testing involves applying an AC current to the battery and measuring the voltage to determine the battery's resistance. Conductance testing applies an AC voltage and measures the current. Both techniques can identify internal component deterioration over time by tracking impedance or conductance changes, and help determine when a performance capacity test is needed. The tests provide information without discharging the battery.
Monitoring of Lead Acid Batteries - an Eltek White PaperEltek
Eltek's Gunnar Hedlund demonstrates different methods of predicting premature capabity loss in your battery park.
No foolproof indicators/tools for knowing and predicting the health and life of a lead acid battery have been evolved or devised. The only way to truly determine the health of a standby lead-acid battery is to perform a 100 % capacity test, according to the battery manufacturers discharge table.
Such a capacity test means that the battery needs to be disconnected from the load and another back-up battery connected when the capacity test is performed. However, comprehensive controllers and instruments are now able to find failing cells without this test and while the battery system is online.
A large number of techniques have been explored and tried out in the field. No single method or test instrument is capable of foolproof prediction about the residual capacity without performing a 100% capacity test. On the other hand, by combining some of them the state of health and expected residual life of the battery can be predicted more precisely and reliably. This is especially true in the finding of failing cells in a standby lead-acid battery.
Power Circuits and Transforers-Unit 3 Labvolt Student Manualphase3-120A
This document discusses determining equivalent capacitance for series and parallel capacitors. It explains that capacitance opposes changes in voltage across capacitor terminals and depends on factors like dielectric material and plate size/spacing. The exercise objectives are to calculate equivalent capacitance using circuit measurements and explain how capacitance values combine in series and parallel configurations.
This document summarizes a study that evaluated the performance and durability of six different electrochemical capacitor technologies over more than 10,000 hours of aging. The capacitors were aged at constant voltage and temperature and periodically tested. Failure was defined as a 30% loss of capacitance or doubling of resistance. Lifetime distributions were determined and showed that Maxwell, Ioxus, and Nippon Chemi-Con capacitors exceeded manufacturer specifications, while properties of JM Energy capacitors changed little. Yunasko capacitors exhibited the longest lifetime in terms of capacitance retention despite resistance tripling.
Introduction
Very low frequency (VLF) AC voltage testing in the
frequency range from 0.01 to 1 Hz is increasingly
being used for both high voltage (Hi-Pot) acceptance
and condition assessment of installed large
capacitance power components [IEEE standards,
IEC standard, etc.].
The main advantage of such tests is the low amount
of reactive power needed compared to testing at
power frequency. Today, equipment for VLF afterlaying
tests are becoming available at voltages up
to 400 kV. In addition, diagnostic parameters as
for example partial discharge activity and dielectric
losses, are regularly measured using VLF voltages.
The document summarizes research on supercapacitor technology conducted by YUNASKO. It finds that:
1) The inner resistance and RC-constant of carbon-carbon supercapacitors can be reduced to a limit of 0.05 seconds through design improvements, allowing for power densities up to 200 kW/kg.
2) Operating temperatures up to 100°C and voltages up to 3V are achievable through new electrolyte formulations but limits energy density to 6-7 Wh/kg.
3) Hybrid devices combining battery and supercapacitor electrodes can substantially increase energy density to 50-60 Wh/kg while maintaining high power, though limiting cycle life to around 10,000 cycles.
The document discusses energy storage systems and their applications in electric vehicles. It provides details on different battery technologies used in HEVs, including their composition, characteristics, and parameters. Lead-acid batteries are currently most widely used due to their low cost but lithium-ion batteries have higher energy density and are gaining popularity. The document compares various battery technologies such as lead-acid, nickel-cadmium, nickel-metal hydride, and lithium-ion in terms of their specifications and suitability for electric vehicles.
Resonance of a distribution feeder with a saturable core fault current limiterFranco Moriconi
1) A resonance event occurred on a distribution feeder with a saturable core fault current limiter installed. When the limiter's DC bias current was lost, its reactance increased, allowing resonance between the feeder's inductive and capacitive elements.
2) Voltage on the feeder rose until a capacitor bank opened. When a second bank closed, resonance reoccurred, sustaining high voltage until the limiter was bypassed.
3) Analysis from the system and limiter perspectives showed agreement. Under low load and full limiter insertion, the feeder properties allowed a damped resonant condition. Suppression measures were proposed.
A Comparative Analysis of Cell Balancing Techniques For Battery Management Sy...IRJET Journal
This document compares and analyzes different cell balancing techniques for battery management systems. It discusses both passive and active cell balancing methods. Passive techniques balance cells by discharging excess energy through resistors, wasting energy as heat. Active balancing transfers energy between cells using capacitors or inductors, from higher to lower voltage cells, improving efficiency. The document simulates these techniques using MATLAB and examines how circuit parameters affect system performance. It concludes that passive balancing is best for low-power applications while active balancing is more suitable for high-power applications like electric vehicles. Proper cell balancing extends battery life and ensures safe operation.
Monitoring of Lead Acid Batteries - an Eltek White PaperEltek
Eltek's Gunnar Hedlund demonstrates different methods of predicting premature capabity loss in your battery park.
No foolproof indicators/tools for knowing and predicting the health and life of a lead acid battery have been evolved or devised. The only way to truly determine the health of a standby lead-acid battery is to perform a 100 % capacity test, according to the battery manufacturers discharge table.
Such a capacity test means that the battery needs to be disconnected from the load and another back-up battery connected when the capacity test is performed. However, comprehensive controllers and instruments are now able to find failing cells without this test and while the battery system is online.
A large number of techniques have been explored and tried out in the field. No single method or test instrument is capable of foolproof prediction about the residual capacity without performing a 100% capacity test. On the other hand, by combining some of them the state of health and expected residual life of the battery can be predicted more precisely and reliably. This is especially true in the finding of failing cells in a standby lead-acid battery.
Power Circuits and Transforers-Unit 3 Labvolt Student Manualphase3-120A
This document discusses determining equivalent capacitance for series and parallel capacitors. It explains that capacitance opposes changes in voltage across capacitor terminals and depends on factors like dielectric material and plate size/spacing. The exercise objectives are to calculate equivalent capacitance using circuit measurements and explain how capacitance values combine in series and parallel configurations.
This document summarizes a study that evaluated the performance and durability of six different electrochemical capacitor technologies over more than 10,000 hours of aging. The capacitors were aged at constant voltage and temperature and periodically tested. Failure was defined as a 30% loss of capacitance or doubling of resistance. Lifetime distributions were determined and showed that Maxwell, Ioxus, and Nippon Chemi-Con capacitors exceeded manufacturer specifications, while properties of JM Energy capacitors changed little. Yunasko capacitors exhibited the longest lifetime in terms of capacitance retention despite resistance tripling.
Introduction
Very low frequency (VLF) AC voltage testing in the
frequency range from 0.01 to 1 Hz is increasingly
being used for both high voltage (Hi-Pot) acceptance
and condition assessment of installed large
capacitance power components [IEEE standards,
IEC standard, etc.].
The main advantage of such tests is the low amount
of reactive power needed compared to testing at
power frequency. Today, equipment for VLF afterlaying
tests are becoming available at voltages up
to 400 kV. In addition, diagnostic parameters as
for example partial discharge activity and dielectric
losses, are regularly measured using VLF voltages.
The document summarizes research on supercapacitor technology conducted by YUNASKO. It finds that:
1) The inner resistance and RC-constant of carbon-carbon supercapacitors can be reduced to a limit of 0.05 seconds through design improvements, allowing for power densities up to 200 kW/kg.
2) Operating temperatures up to 100°C and voltages up to 3V are achievable through new electrolyte formulations but limits energy density to 6-7 Wh/kg.
3) Hybrid devices combining battery and supercapacitor electrodes can substantially increase energy density to 50-60 Wh/kg while maintaining high power, though limiting cycle life to around 10,000 cycles.
The document discusses energy storage systems and their applications in electric vehicles. It provides details on different battery technologies used in HEVs, including their composition, characteristics, and parameters. Lead-acid batteries are currently most widely used due to their low cost but lithium-ion batteries have higher energy density and are gaining popularity. The document compares various battery technologies such as lead-acid, nickel-cadmium, nickel-metal hydride, and lithium-ion in terms of their specifications and suitability for electric vehicles.
Resonance of a distribution feeder with a saturable core fault current limiterFranco Moriconi
1) A resonance event occurred on a distribution feeder with a saturable core fault current limiter installed. When the limiter's DC bias current was lost, its reactance increased, allowing resonance between the feeder's inductive and capacitive elements.
2) Voltage on the feeder rose until a capacitor bank opened. When a second bank closed, resonance reoccurred, sustaining high voltage until the limiter was bypassed.
3) Analysis from the system and limiter perspectives showed agreement. Under low load and full limiter insertion, the feeder properties allowed a damped resonant condition. Suppression measures were proposed.
A Comparative Analysis of Cell Balancing Techniques For Battery Management Sy...IRJET Journal
This document compares and analyzes different cell balancing techniques for battery management systems. It discusses both passive and active cell balancing methods. Passive techniques balance cells by discharging excess energy through resistors, wasting energy as heat. Active balancing transfers energy between cells using capacitors or inductors, from higher to lower voltage cells, improving efficiency. The document simulates these techniques using MATLAB and examines how circuit parameters affect system performance. It concludes that passive balancing is best for low-power applications while active balancing is more suitable for high-power applications like electric vehicles. Proper cell balancing extends battery life and ensures safe operation.
The document discusses various characterization techniques used to analyze battery materials, including X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDX). XRD is used to verify crystal structure by analyzing diffraction patterns. TGA analyzes weight changes with temperature to measure thermal stability and composition. SEM provides high-resolution images of morphology and composition through backscattered electrons and EDX. These techniques are applied to characterize the synthesized sodium titanium phosphate (NaTi2(PO4)3) battery anode material.
1) Sudden impedance rise (SIR) in stationary batteries is a common cause of UPS failures that occurs when a battery's internal resistance exponentially rises over 2-4 weeks.
2) SIR can happen at any point in a battery's usable life and leads to battery failure if not replaced. It only takes one failed cell to cause a string failure and potential explosion under load.
3) Regular battery monitoring and maintenance is important to detect SIR early through trend analysis of resistance and voltage readings, allowing problematic batteries to be replaced preventively before failure occurs.
The document describes a study that investigates using series compensation to improve voltage quality in isolated power systems. The study aims to develop a control method for the series compensator to regulate the fundamental component of the sensitive load terminal voltage. This is achieved by controlling harmonic power flow through adjustment of the phase angle. The series compensator is able to import harmonic power from the external system to improve the sensitive load's voltage sag ride-through capability. The document presents models of the system components and analyzes harmonic mitigation and power flow control using the series compensator.
This document discusses sheath voltage limiters (SVLs), which are surge arresters used to protect the outer jacket of underground high voltage cables. SVLs limit the voltage stress across the cable jacket during transient overvoltage events like faults, switching surges and lightning strikes to prevent puncture and moisture ingress. The document provides guidelines for selecting the proper rating for SVLs, including calculating the voltage that could appear on the cable sheath during faults based on cable characteristics, and ensuring the SVL's voltage rating is above this level so it does not conduct during faults. It also discusses using simulations and margins of protection to determine if the SVL can adequately protect the cable jacket from other transient overvoltages.
This document discusses the design of electric vehicle battery packs. It covers topics such as state of charge, implications of the SOC curve, measuring SOC accurately, what comprises a battery pack, building packs from cells by connecting them in series and parallel, modules and packs, electrical design considerations, insulation, costs, and insulation testing. The goal is to conceptualize battery pack design to optimize performance while ensuring safety.
The document proposes and implements an accurate electrical battery model in Matlab to simulate the dynamic behavior of lithium-ion batteries. The model considers nonlinear open circuit voltage, charge/discharge current, and transient response time. It was verified using experimental data and found to adequately reflect real-time battery behavior. The model can predict battery runtime and I-V performance.
One of the common methods that developed to predict state of charge is open circuit voltage (OCV) method. The problem which commonly occurs is to find the correction parameter between open circuit voltage and loaded voltage of the battery. In this research, correlation between state of charge measurement at loaded condition of a Panasonic LC-VA1212NA1, which is a valve-regulated lead acid (VRLA) battery, and open circuit voltage had been analyzed. Based on the results of research, correlation between battery’s measured voltage under loaded condition and open circuit voltage could be approached by two linearization area. It caused by K v ’s values tend to increase when measured voltage under loaded condition V M < 11.64 volt. However, K v values would be relatively stable for every V M ≥ 11.64 volts. Therefore, estimated state of charge value, in respect to loaded battery voltage, would increase slower on V M < 11.64 volts and faster on other range.
The document discusses the basics of electrochemical cells and batteries. It covers topics like nominal voltage, operating voltage, capacity, self-discharge, depth of discharge, energy density, service life, and shelf life. It also discusses primary cells like Leclanché cells, alkaline cells, and lithium primary cells. Their chemistries and applications are explained. Secondary cells and batteries are defined. The differences between galvanic cells and electrolytic cells are highlighted.
A robust state of charge estimation for multiple models of lead acid battery ...journalBEEI
An accurate estimation technique of the state of charge (SOC) of batteries is an essential task of the battery management system. The adaptive Kalman filter (AEKF) has been used as an obsever to investigate the SOC estimation effectiveness. Therefore, The SOC is a reflexion of the chemistry of the cell which it is the key parameter for the battery management system. It is very complex to monitor the SOC and control the internal states of the cell. Three battery models are proposed and their state space models have been established, their parameters were identified by applying the least square method. However, the SOC estimation accuracy of the battery depends on the model and the efficiency of the algorithm. In this paper, AEKF technique is presented to estimate the SOC of Lead acid battery. The experimental data is used to identify the parameters of the three models and used to build different open circuit voltage–state of charge (OCV-SOC) functions relationship. The results shows that the SOC estimation based-model which has been built by hight order RC model can effectively limit the error, hence guaranty the accuracy and robustness.
State of Charge Vs Depth of Discharge
Battery Indicator
Safety Label
Lead Acid Battery Standard Performance
The difference between Conventional Batteries, Hybrid Batteries and MF Batteries
Lagging cells in lead acid batteries
Cycling
Lead-Acid Cell and Battery Troubles and Their Remedies
Water Loss in VRLA
Premature Capacity Loss in VRLA
References
The document discusses electrochemical energy storage and its importance for alternative energy applications. It outlines some key challenges with energy storage, including the need for devices with high power and energy capabilities, long life, fast charging, and portability. The author proposes using hybrid energy storage systems that integrate multiple device types to optimize performance for different applications and timescales. The remainder of the document focuses on lithium-ion battery limitations and using mechanical models to understand capacity fade through stresses induced during operation.
This document provides a basic introduction to electronics and defines some key concepts. It explains that voltage causes current flow, and that current can be used to power devices. It defines voltage and resistance, the units used to measure them, and how components like batteries, resistors, ammeters and lamps function in simple circuits. The document aims to provide just enough knowledge to understand simple control circuits for devices described later.
Power Quality Enhancement in an Isolated Power System Using Series CompensationIJMER
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
International Journal of Modern Engineering Research (IJMER) covers all the fields of engineering and science: Electrical Engineering, Mechanical Engineering, Civil Engineering, Chemical Engineering, Computer Engineering, Agricultural Engineering, Aerospace Engineering, Thermodynamics, Structural Engineering, Control Engineering, Robotics, Mechatronics, Fluid Mechanics, Nanotechnology, Simulators, Web-based Learning, Remote Laboratories, Engineering Design Methods, Education Research, Students' Satisfaction and Motivation, Global Projects, and Assessment…. And many more.
The document discusses automotive batteries and their characteristics. It begins by introducing lead-acid batteries and their electrochemical reactions that allow them to store and produce electrical energy. It then discusses (1) the construction of lead-acid batteries, including their lead plates and sulfuric acid electrolyte, (2) how their chemical reactions allow them to convert chemical energy into electrical energy during discharge and vice versa during charging, and (3) common tests used to determine a battery's state of charge such as hydrometer tests and heavy duty discharge tests. The document emphasizes that a battery's rating is determined by how much current it can produce and for how long, with common ratings including amp-hour capacity, reserve capacity, and cold cranking
Development of a novel ultracapacitor electricTania Martinez
This document summarizes a research paper on the development of an ultracapacitor electric vehicle (EV) and methods to cope with voltage variation in the ultracapacitor storage system. The key points are:
1) The researchers at the University of Tokyo developed a novel EV that is powered solely by an ultracapacitor storage system, without a DC-DC converter, to improve weight, space, and energy efficiency.
2) They designed an inverter that can operate between 50-200V to utilize over 90% of the ultracapacitor's energy storage, compared to only 10-20% usage in previous systems.
3) Dq-axis vector control of the interior permanent magnet synchronous motor is used
1. The document discusses series circuits and how voltage is divided among resistors in series. It explains that the total resistance of resistors in series is equal to the sum of the individual resistances.
2. A key concept covered is the voltage divider rule - the voltage across each resistor in a series circuit is directly proportional to the ratio of its resistance to the total resistance.
3. Applications of voltage dividers include using potentiometers (variable resistors) to obtain a variable output voltage from a fixed voltage source.
This document summarizes the performance analysis of VRLA batteries under continuous operation. It discusses testing various capacity VRLA battery banks to analyze electrical and thermal characteristics. The batteries were tested with 80% depth of discharge over 32-43 hours. A battery regenerator was used to reduce sulfation and a battery measurement system monitored individual cell voltages. Testing showed battery capacity and lifespan increased after regeneration, with backups extending 1-2 hours. Larger 550Ah-682Ah batteries showed greater improvements than the 300Ah batteries tested. Regenerating existing batteries can save significant power compared to replacing them.
C-rate refers to the rate at which a battery is charged or discharged relative to its maximum capacity. A 1C rate means that the current during charge or discharge equals the battery's rated capacity in amp-hours. Higher C-rates like 2C provide less discharge time while lower C-rates like 0.5C provide more discharge time. Battery capacity measurements can vary between tests and depend on factors like temperature, chemistry, and C-rate used. Non-invasive techniques like impedance spectroscopy can estimate capacity and health quickly but provide estimated values compared to the standard charge/discharge cycle test.
This document discusses the optimal use of multilayer ceramic capacitors (MLCCs) for synchronous buck converters used in point-of-load applications. It describes how the electrical parameters of MLCCs are highly dependent on factors like voltage, frequency, temperature and package size. The document provides guidelines for selecting the right type, value, size and number of MLCCs for the input and output filters of synchronous buck converters. It presents an application example and experimental results to demonstrate the effectiveness of the proposed design methodology.
The document discusses various characterization techniques used to analyze battery materials, including X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDX). XRD is used to verify crystal structure by analyzing diffraction patterns. TGA analyzes weight changes with temperature to measure thermal stability and composition. SEM provides high-resolution images of morphology and composition through backscattered electrons and EDX. These techniques are applied to characterize the synthesized sodium titanium phosphate (NaTi2(PO4)3) battery anode material.
1) Sudden impedance rise (SIR) in stationary batteries is a common cause of UPS failures that occurs when a battery's internal resistance exponentially rises over 2-4 weeks.
2) SIR can happen at any point in a battery's usable life and leads to battery failure if not replaced. It only takes one failed cell to cause a string failure and potential explosion under load.
3) Regular battery monitoring and maintenance is important to detect SIR early through trend analysis of resistance and voltage readings, allowing problematic batteries to be replaced preventively before failure occurs.
The document describes a study that investigates using series compensation to improve voltage quality in isolated power systems. The study aims to develop a control method for the series compensator to regulate the fundamental component of the sensitive load terminal voltage. This is achieved by controlling harmonic power flow through adjustment of the phase angle. The series compensator is able to import harmonic power from the external system to improve the sensitive load's voltage sag ride-through capability. The document presents models of the system components and analyzes harmonic mitigation and power flow control using the series compensator.
This document discusses sheath voltage limiters (SVLs), which are surge arresters used to protect the outer jacket of underground high voltage cables. SVLs limit the voltage stress across the cable jacket during transient overvoltage events like faults, switching surges and lightning strikes to prevent puncture and moisture ingress. The document provides guidelines for selecting the proper rating for SVLs, including calculating the voltage that could appear on the cable sheath during faults based on cable characteristics, and ensuring the SVL's voltage rating is above this level so it does not conduct during faults. It also discusses using simulations and margins of protection to determine if the SVL can adequately protect the cable jacket from other transient overvoltages.
This document discusses the design of electric vehicle battery packs. It covers topics such as state of charge, implications of the SOC curve, measuring SOC accurately, what comprises a battery pack, building packs from cells by connecting them in series and parallel, modules and packs, electrical design considerations, insulation, costs, and insulation testing. The goal is to conceptualize battery pack design to optimize performance while ensuring safety.
The document proposes and implements an accurate electrical battery model in Matlab to simulate the dynamic behavior of lithium-ion batteries. The model considers nonlinear open circuit voltage, charge/discharge current, and transient response time. It was verified using experimental data and found to adequately reflect real-time battery behavior. The model can predict battery runtime and I-V performance.
One of the common methods that developed to predict state of charge is open circuit voltage (OCV) method. The problem which commonly occurs is to find the correction parameter between open circuit voltage and loaded voltage of the battery. In this research, correlation between state of charge measurement at loaded condition of a Panasonic LC-VA1212NA1, which is a valve-regulated lead acid (VRLA) battery, and open circuit voltage had been analyzed. Based on the results of research, correlation between battery’s measured voltage under loaded condition and open circuit voltage could be approached by two linearization area. It caused by K v ’s values tend to increase when measured voltage under loaded condition V M < 11.64 volt. However, K v values would be relatively stable for every V M ≥ 11.64 volts. Therefore, estimated state of charge value, in respect to loaded battery voltage, would increase slower on V M < 11.64 volts and faster on other range.
The document discusses the basics of electrochemical cells and batteries. It covers topics like nominal voltage, operating voltage, capacity, self-discharge, depth of discharge, energy density, service life, and shelf life. It also discusses primary cells like Leclanché cells, alkaline cells, and lithium primary cells. Their chemistries and applications are explained. Secondary cells and batteries are defined. The differences between galvanic cells and electrolytic cells are highlighted.
A robust state of charge estimation for multiple models of lead acid battery ...journalBEEI
An accurate estimation technique of the state of charge (SOC) of batteries is an essential task of the battery management system. The adaptive Kalman filter (AEKF) has been used as an obsever to investigate the SOC estimation effectiveness. Therefore, The SOC is a reflexion of the chemistry of the cell which it is the key parameter for the battery management system. It is very complex to monitor the SOC and control the internal states of the cell. Three battery models are proposed and their state space models have been established, their parameters were identified by applying the least square method. However, the SOC estimation accuracy of the battery depends on the model and the efficiency of the algorithm. In this paper, AEKF technique is presented to estimate the SOC of Lead acid battery. The experimental data is used to identify the parameters of the three models and used to build different open circuit voltage–state of charge (OCV-SOC) functions relationship. The results shows that the SOC estimation based-model which has been built by hight order RC model can effectively limit the error, hence guaranty the accuracy and robustness.
State of Charge Vs Depth of Discharge
Battery Indicator
Safety Label
Lead Acid Battery Standard Performance
The difference between Conventional Batteries, Hybrid Batteries and MF Batteries
Lagging cells in lead acid batteries
Cycling
Lead-Acid Cell and Battery Troubles and Their Remedies
Water Loss in VRLA
Premature Capacity Loss in VRLA
References
The document discusses electrochemical energy storage and its importance for alternative energy applications. It outlines some key challenges with energy storage, including the need for devices with high power and energy capabilities, long life, fast charging, and portability. The author proposes using hybrid energy storage systems that integrate multiple device types to optimize performance for different applications and timescales. The remainder of the document focuses on lithium-ion battery limitations and using mechanical models to understand capacity fade through stresses induced during operation.
This document provides a basic introduction to electronics and defines some key concepts. It explains that voltage causes current flow, and that current can be used to power devices. It defines voltage and resistance, the units used to measure them, and how components like batteries, resistors, ammeters and lamps function in simple circuits. The document aims to provide just enough knowledge to understand simple control circuits for devices described later.
Power Quality Enhancement in an Isolated Power System Using Series CompensationIJMER
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
International Journal of Modern Engineering Research (IJMER) covers all the fields of engineering and science: Electrical Engineering, Mechanical Engineering, Civil Engineering, Chemical Engineering, Computer Engineering, Agricultural Engineering, Aerospace Engineering, Thermodynamics, Structural Engineering, Control Engineering, Robotics, Mechatronics, Fluid Mechanics, Nanotechnology, Simulators, Web-based Learning, Remote Laboratories, Engineering Design Methods, Education Research, Students' Satisfaction and Motivation, Global Projects, and Assessment…. And many more.
The document discusses automotive batteries and their characteristics. It begins by introducing lead-acid batteries and their electrochemical reactions that allow them to store and produce electrical energy. It then discusses (1) the construction of lead-acid batteries, including their lead plates and sulfuric acid electrolyte, (2) how their chemical reactions allow them to convert chemical energy into electrical energy during discharge and vice versa during charging, and (3) common tests used to determine a battery's state of charge such as hydrometer tests and heavy duty discharge tests. The document emphasizes that a battery's rating is determined by how much current it can produce and for how long, with common ratings including amp-hour capacity, reserve capacity, and cold cranking
Development of a novel ultracapacitor electricTania Martinez
This document summarizes a research paper on the development of an ultracapacitor electric vehicle (EV) and methods to cope with voltage variation in the ultracapacitor storage system. The key points are:
1) The researchers at the University of Tokyo developed a novel EV that is powered solely by an ultracapacitor storage system, without a DC-DC converter, to improve weight, space, and energy efficiency.
2) They designed an inverter that can operate between 50-200V to utilize over 90% of the ultracapacitor's energy storage, compared to only 10-20% usage in previous systems.
3) Dq-axis vector control of the interior permanent magnet synchronous motor is used
1. The document discusses series circuits and how voltage is divided among resistors in series. It explains that the total resistance of resistors in series is equal to the sum of the individual resistances.
2. A key concept covered is the voltage divider rule - the voltage across each resistor in a series circuit is directly proportional to the ratio of its resistance to the total resistance.
3. Applications of voltage dividers include using potentiometers (variable resistors) to obtain a variable output voltage from a fixed voltage source.
This document summarizes the performance analysis of VRLA batteries under continuous operation. It discusses testing various capacity VRLA battery banks to analyze electrical and thermal characteristics. The batteries were tested with 80% depth of discharge over 32-43 hours. A battery regenerator was used to reduce sulfation and a battery measurement system monitored individual cell voltages. Testing showed battery capacity and lifespan increased after regeneration, with backups extending 1-2 hours. Larger 550Ah-682Ah batteries showed greater improvements than the 300Ah batteries tested. Regenerating existing batteries can save significant power compared to replacing them.
C-rate refers to the rate at which a battery is charged or discharged relative to its maximum capacity. A 1C rate means that the current during charge or discharge equals the battery's rated capacity in amp-hours. Higher C-rates like 2C provide less discharge time while lower C-rates like 0.5C provide more discharge time. Battery capacity measurements can vary between tests and depend on factors like temperature, chemistry, and C-rate used. Non-invasive techniques like impedance spectroscopy can estimate capacity and health quickly but provide estimated values compared to the standard charge/discharge cycle test.
This document discusses the optimal use of multilayer ceramic capacitors (MLCCs) for synchronous buck converters used in point-of-load applications. It describes how the electrical parameters of MLCCs are highly dependent on factors like voltage, frequency, temperature and package size. The document provides guidelines for selecting the right type, value, size and number of MLCCs for the input and output filters of synchronous buck converters. It presents an application example and experimental results to demonstrate the effectiveness of the proposed design methodology.
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Embedded machine learning-based road conditions and driving behavior monitoringIJECEIAES
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https://www.leewayhertz.com/generative-ai-use-cases-and-applications/
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the state-of-the-art Deeplabv3+ architecture with the ResNet18 backbone. The
model is rigorously trained and evaluated, exhibiting remarkable performance
metrics, including an impressive global accuracy of 99.286%, a high-class accuracy of 82.191%, a mean intersection over union (IoU) of 79.900%, a weighted
IoU of 98.620%, and a Boundary F1 (BF) score of 83.303%. Notably, a detailed comparative analysis with existing methods showcases the superiority of
our proposed model. These findings underscore the model’s competence in precise brain tumor localization, underscoring its potential to revolutionize medical
image analysis and enhance healthcare outcomes. This research paves the way
for future exploration and optimization of advanced CNN models in medical
imaging, emphasizing addressing false positives and resource efficiency.
Null Bangalore | Pentesters Approach to AWS IAMDivyanshu
#Abstract:
- Learn more about the real-world methods for auditing AWS IAM (Identity and Access Management) as a pentester. So let us proceed with a brief discussion of IAM as well as some typical misconfigurations and their potential exploits in order to reinforce the understanding of IAM security best practices.
- Gain actionable insights into AWS IAM policies and roles, using hands on approach.
#Prerequisites:
- Basic understanding of AWS services and architecture
- Familiarity with cloud security concepts
- Experience using the AWS Management Console or AWS CLI.
- For hands on lab create account on [killercoda.com](https://killercoda.com/cloudsecurity-scenario/)
# Scenario Covered:
- Basics of IAM in AWS
- Implementing IAM Policies with Least Privilege to Manage S3 Bucket
- Objective: Create an S3 bucket with least privilege IAM policy and validate access.
- Steps:
- Create S3 bucket.
- Attach least privilege policy to IAM user.
- Validate access.
- Exploiting IAM PassRole Misconfiguration
-Allows a user to pass a specific IAM role to an AWS service (ec2), typically used for service access delegation. Then exploit PassRole Misconfiguration granting unauthorized access to sensitive resources.
- Objective: Demonstrate how a PassRole misconfiguration can grant unauthorized access.
- Steps:
- Allow user to pass IAM role to EC2.
- Exploit misconfiguration for unauthorized access.
- Access sensitive resources.
- Exploiting IAM AssumeRole Misconfiguration with Overly Permissive Role
- An overly permissive IAM role configuration can lead to privilege escalation by creating a role with administrative privileges and allow a user to assume this role.
- Objective: Show how overly permissive IAM roles can lead to privilege escalation.
- Steps:
- Create role with administrative privileges.
- Allow user to assume the role.
- Perform administrative actions.
- Differentiation between PassRole vs AssumeRole
Try at [killercoda.com](https://killercoda.com/cloudsecurity-scenario/)
Optimizing Gradle Builds - Gradle DPE Tour Berlin 2024Sinan KOZAK
Sinan from the Delivery Hero mobile infrastructure engineering team shares a deep dive into performance acceleration with Gradle build cache optimizations. Sinan shares their journey into solving complex build-cache problems that affect Gradle builds. By understanding the challenges and solutions found in our journey, we aim to demonstrate the possibilities for faster builds. The case study reveals how overlapping outputs and cache misconfigurations led to significant increases in build times, especially as the project scaled up with numerous modules using Paparazzi tests. The journey from diagnosing to defeating cache issues offers invaluable lessons on maintaining cache integrity without sacrificing functionality.
Introduction- e - waste – definition - sources of e-waste– hazardous substances in e-waste - effects of e-waste on environment and human health- need for e-waste management– e-waste handling rules - waste minimization techniques for managing e-waste – recycling of e-waste - disposal treatment methods of e- waste – mechanism of extraction of precious metal from leaching solution-global Scenario of E-waste – E-waste in India- case studies.
2. Typically the vented (flooded) lead acid battery is contained in a clear container and the condition of
the cell is determined via float voltage checks, electrolyte specific gravity checks and a visual
inspection of the internal components. The internal components such as plate grids and active
material, straps joining the plates in parallel, separators, electrolyte, and sediment level and color
are inspected to determine how they may have changed from their original condition such that the
capacity of the cell would be affected.
For example, if the plates had grown significantly the pasted active material (Pb02) to grid bond could
be affected which would increase the cell's resistance and thus reduce it's capacity. Or it may be
observed that there is excessive black active material sediment in the base of the cell - this loss of
active material would also result in an increase in cell resistance and loss of capacity, while grid
corrosion and shedding are the normal wearout mode for the vented lead acid cell, these phenomena
can be greatly accelerated due to overcharging, excessive cycling and high temperature operation.
While a visual inspection does not reveal all the possible problems which can occur that ailed the
cell's ability to perform, and when the recommended performance capacity tests have not been
periodically performed, observed internal component deterioration is the indication that a performance
capacity test should be performed as soon as possible to determine the reliability of the battery.
The typical valve regulated lead acid (VRLA) multicell battery differs from the typical vented cell in
that the container is sealed, preventing electrolyte additions and sampling and opaque precluding
visual inspection of the internal components. This then limits the maintenance of the cell to checks of
the float charging voltage and current, battery temperature and periodic performance capacity tests,
The typical VRLA battery is comprised of the components as shown in Figure 1. Figure 2 presents an
equivalent circuit of the VRLA cell with the plate grids and active material, plate paralleling strap and
electrolyte contributing approximately 80% of the total resistance of the battery. Any change in these
components, such as grid corrosion, shedding of active material, strap or grip to strap corrosion, or
drying of the limited supply of electrolyte will be reflected in an increase in the resistance of the
battery. While techniques of discharging the battery at different rates to determine its resistance do
exist, they are neither convenient or practical to perform in an operational environment.
41-7271/0512/CD 2 www.cdtechno.com
3. 41-7271/0512/CD 3 www.cdtechno.com
While not a requirement of the periodic maintenance program, battery impedance and conductance
testing techniques have been developed in an effort to determine the condition of the internal
components and serve as a trending and troubleshooting tool.
By utilizing AC testing techniques the impedance (or conductance) of the battery can be determined
with no resulting discharge of the battery and little if any interruption in the service it provides. The
impedance is actually the resistance of the cell to the flow of AC current as presented by the
resistance (R) and inductive and capacitive reactance (XL and XC respectively) of the internal
components. The impedance of the cell is frequency dependent, and somewhat different results will
be obtained depending on the test equipment and test current frequency utilized. However the
impedance can generally be expressed as:
Z = √ R2
+ (XL + XC)2
Equation 1
Where: Z = impedance in ohms
R = DC resistance in ohms
XL = inductive reactance (2 fL) in ohms
XC = capacitive reactance (1/2 fC) in ohms
Figure 1
Cover
Intercell Welded Connection
Pos. Pasted Plate
Strap joining neg.
plates in parallel
AGM Separator
Neg. Pasted Plate
Lead Alloy Grid
Container
4. The absolute value of the AC impedance of the cell can be determined by simply forcing a specified
AC current through the battery and measuring the AC voltage developed across the terminals. The
impedance is then calculated as:
Z = E
Equation 2
The injection of test current through the cell under test can be accomplished with a circuit similar to
that of Figure 3. The driving AC current is developed at the transformer secondary winding and
adjusted to the specified level (eg. 10 amperes) and is then capacitively coupled to the battery under
test by the capacitor C1. The AC voltage then developed across each cell or battery in the string
(E = I x Z) is measured and the impedance is calculated as per equation 2.
Since the test current amplitude and frequency is the same for each cell and battery in the string each
time the test is performed, the calculated impedance for each cell and battery can be used to compare cells
and batteries within the string and for changes over a period of time.
Typically the VRLA cells and batteries will all have an impedance of +/-20% of the average when new.
This range will reduce as the cells/batteries continue in float service and the oxygen recombination
cycle stabilizes and equalizes between the cells. As the cells age the average measured impedance
will gradually increase indicating progressive deterioration of the cell internal components (plates and
connecting straps) and/or drying of the electrolyte. Should a cell short, its impedance would initially
decline dramatically. However, as the cell discharged due to the short, the electrolyte is consumed
producing water and lead sulfate which then causes the impedance of the cell to rise to a very high
value – approaching that of the short circuit itself. Naturally, an open would result in a dramatic
increase in impedance.
Admittance is the reciprocal of impedance (1/Z) and conductance is the reciprocal of the real part or
resistive portion of impedance (1/R). The conductance test is similar in effect to the impedance test
however, in the conductance test a specified AC voltage is capacitively coupled to the test cell or battery
and the resulting AC current flowing through the unit under test is measured. The conductance (C) is
then calculated as 1/(E/I) or simply C = I/E. The unique characteristic of some popular current
conductance testers is the ability to ignore the inductive and capacitive reactance of the cell or
battery and directly measure only the resistive components affect.
41-7271/0512/CD 4 www.cdtechno.com
I
5. 41-7271/0512/CD 5 www.cdtechno.com
Conductance measurement results in mhos may be used in the same manner as impedance values
in ohms to troubleshoot a battery and trend the unit's condition over a period of time.
The manner in which the cell and battery impedance, conductance and capacity may vary with age is
noted in figure 4. If a cell or battery impedance or conductance should vary more than 50% of the
value from when it was new, the battery should be further evaluated to determine the cause. This
evaluation should include a performance capacity test.
It is important to recognize that neither the impedance or conductance test is capable of replacing the
actual performance capacity test since they are not able to provide a clear indication of all the potential
problems which can cause a battery to fail. However, they can provide information alerting the technician
to the need for further investigation of some potentially troublesome cells.
Table 1 provides typical values of impedence and conductance for CD Technologies VRLA battery
products as measured with the AVO-Biddle BITE unit and the Midtronics Mdl. 5000 conductance
tester respectively. The values are typical and the actual value measured on a new individual battery
may vary +/-20% from the value shown. Also, the values measured will vary from that in the table with
the type and model of test equipment utilized. The significance of values measured lies not so much
in the specific value but how the value changes from it's original value over a period of time.
Figure 4 - VRLA Battery Impedance and
Conductance Vs. Capacity and Age
6. BATTERY IMPEDANCE AND AC RIPPLE VOLTAGE
Usually, communications rectifiers are highly filtered and there is very little AC ripple voltage
impressed on the connected battery. However, substation and UPS battery chargers typically impress
a significant AC ripple voltage on the connected battery causing a measurable AC current to flow
through the battery. If all cells had identical impedance, this AC ripple voltage would be evenly divided
across the cells. However, since the same AC current flows through all the cells, those cells with
higher impedance will exhibit a greater AC voltage across the terminals (E = I x Z) while those with
lower impedance will exhibit a lower AC voltage. While the AC current could be measured and the
impedance calculated as:
Z=E/I
For troubleshooting purposes the measured AC voltages per battery can be compared directly and
treated as though they were impedance measurements since the same current flows through all
units. Figure 5 indicates how the readings might be interpreted.
41-7271/0512/CD 6 www.cdtechno.com
Impedance Conductance
Milli-Ohms Mhos
UPS12-100MR 7.17 603
UPS12-150MR 4.03 1007
UPS12-210MR 3.81 1138
UPS12-300MR 3.64 1669
UPS12-350MR 2.38 1914
UPS12-400MR 2.15 2079
UPS12-490MR 2.64 1844
UPS12-540MR 2.21 2032
UPS12-615MRF 2.0 2400
UPS6-620MR Ltd Data Ltd Data
UPS12-700MRF 2.1 2500
TEL12-30/SLC 5.30 752
TEL12-45/SLC 4.74 858
TEL12-70 3.35 1326
TEL12-80/SLC 3.02 1467
TEL12-90 2.77 1549
TEL12-105FS 3.10 1300
TEL12-105FNSG Ltd Data 1050
TEL12-115FNG Ltd Data 1090
TEL12-125 2.69 1747
TEL12-145FW Ltd Data Ltd Data
TEL12-155F/FG Ltd Data 1120
TEL12-160FW Ltd Data 1780
TEL12-160F Ltd Data 1500
TEL12-170F/FG Ltd Data 1400
TEL12-180F Ltd Data 1510
TEL12-190F/FG Ltd Data 1450
TEL12-210F/FG Ltd Data 1500
TEL6-180 Ltd Data Ltd Data
DCS-33IT/HIT 5.30 784
DCS-50IT 4.75 916
DCS-75IT/HIT 3.32 1328
DCS-88HIT 2.88 1592
DCS-100HIT 3.01 1515
Ltd Data - More Data Needed
Deep
Cycle
Telecom
UPS
Model Number
7. The calculated values of impedance using this method will not be the same as that derived using
commercial test equipment since the frequency of the AC ripple is different and it may also vary from
time to time. Also, the value of the measured AC voltage per battery may vary at different times due
to variation of the amplitude of the AC ripple voltage across the total string. However, with these
constraints in mind, this technique can still provide a valuable troubleshooting tool.
VRLA BATTERY IMPEDANCE (RIPPLE VOLTAGE) MEAsUREMENT
41-7271/0512/CD 7 www.cdtechno.com
8. BATTERY IMPEDANCE AND CONDUCTANCE Vs. TEMPERATURE
It is important that when battery impedance or conductance measurements are taken that the temperature
of the battery be measured and recorded. As noted in Figure 6, the values are only moderately
affected above 77°F however, at cooler temperatures the impedance of the battery is greatly increased.
When comparing values derived over a period of time the values must be normalized for temperature
to obtain comparable results.
Any data, descriptions or specifications presented herein are subject to revision by CD Technologies, Inc.
without notice. While such information is believed to be accurate as indicated herein, CD Technologies, Inc.
makes no warranty and hereby disclaims all warranties, express or implied, with regard to the accuracy or
completeness of such information. Further, because the product(s) featured herein may be used under conditions
beyond its control, CD Technologies, Inc. hereby disclaims all warranties, either express or implied, concerning
the fitness or suitability of such product(s) for any particular use or in any specific application or arising from any
course of dealing or usage of trade. The user is solely responsible for determining the suitability of the product(s)
featured herein for user’s intended purpose and in user’s specific application.
Copyright 2012 CD TECHNOLOGIES, INC. Printed in U.S.A. 41-7271 0512/CD
1400 Union Meeting Road
P.O. Box 3053 • Blue Bell, PA 19422-0858
(215) 619-2700 • Fax (215) 619-7899 • (800) 543-8630
customersvc@cdtechno.com
www.cdtechno.com