Charging sealed lead acid (SLA) batteries requires an intelligent charger to maximize battery life. Simple constant current or constant voltage chargers can reduce battery life expectancy. Maximizing battery life involves understanding the battery's chemistry and using a multi-stage charging technique that includes a bulk constant current charge, absorption constant voltage charge, and float intermittent charge while monitoring voltage and temperature. An intelligent charger that implements temperature compensation can optimize charging to extend battery life.
Boost and equalize charge with limited voltage window - an Eltek White PaperEltek
Designing a DC system requires consideration of the ability to work within a certain DC voltage
window. The maximum voltage provides the high-end of a voltage range that is available to
charge the battery, whereas, the minimum voltage gives the lowest voltage within that range that
is acceptable to the system so that the battery can be discharged.
It is not unusual for this voltage window to be very narrow, where specifications can be as close
as +/- 10% from the nominal DC voltage.
This limited system voltage window can be a challenge to take into consideration when
designing a DC system, especially when using it with Ni-Cd back up batteries that have a wide
voltage window. What is needed is a boost or equalize charge to reach the maximum voltage
that is effective for the attached batteries.
This paper will present a different system designed to
Paper presentation offers new paradigm and changes existing perception for the batteries
Authors confirm that they were able to split chemical and electrical parts inside chemical battery thanks to matching parameters of digit currents and voltages
The main output of this split is full reduction of polarization part in internal resistance due to shift in electric neutrality. We would like to share some test results we have been doing for 5 years.
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
TECHNOLOGY AND TREND OF HIGH FREQUENCY BATTERY CHARGER FOR LEAD-ACID BATTERYIAEME Publication
Though battery use increases more and more and the capacity is increased as a
result of short battery use time, research and development is in progress with the
purpose of reducing the charging time and increasing the charging speed due to the
physical limitations and the limitations on technology development. High speed
chargers and high frequency battery chargers used with AC power utilize two
conversion circuit designing methods, and the efficiency and performance of chargers
have been enhanced by using additional PFC, filter, safety circuit, etc. If a lead-acid
battery is charged with a slow charger for general battery, sulfuric acid accumulates
as a by-product of the chemical reaction, which leads to battery performance
deterioration. In order to charge such a battery turning it into the state of initial
performance, a charger which employs high frequency wave is used to prevent
performance deterioration. As it is also important to check the battery state at this
time to ensure quick charging and prevent performance deterioration, we intend to
look into various methods of checking the battery state, changes in the charger
efficiency, and the difference between a high frequency battery charger and a general
slow battery charger.
Boost and equalize charge with limited voltage window - an Eltek White PaperEltek
Designing a DC system requires consideration of the ability to work within a certain DC voltage
window. The maximum voltage provides the high-end of a voltage range that is available to
charge the battery, whereas, the minimum voltage gives the lowest voltage within that range that
is acceptable to the system so that the battery can be discharged.
It is not unusual for this voltage window to be very narrow, where specifications can be as close
as +/- 10% from the nominal DC voltage.
This limited system voltage window can be a challenge to take into consideration when
designing a DC system, especially when using it with Ni-Cd back up batteries that have a wide
voltage window. What is needed is a boost or equalize charge to reach the maximum voltage
that is effective for the attached batteries.
This paper will present a different system designed to
Paper presentation offers new paradigm and changes existing perception for the batteries
Authors confirm that they were able to split chemical and electrical parts inside chemical battery thanks to matching parameters of digit currents and voltages
The main output of this split is full reduction of polarization part in internal resistance due to shift in electric neutrality. We would like to share some test results we have been doing for 5 years.
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
TECHNOLOGY AND TREND OF HIGH FREQUENCY BATTERY CHARGER FOR LEAD-ACID BATTERYIAEME Publication
Though battery use increases more and more and the capacity is increased as a
result of short battery use time, research and development is in progress with the
purpose of reducing the charging time and increasing the charging speed due to the
physical limitations and the limitations on technology development. High speed
chargers and high frequency battery chargers used with AC power utilize two
conversion circuit designing methods, and the efficiency and performance of chargers
have been enhanced by using additional PFC, filter, safety circuit, etc. If a lead-acid
battery is charged with a slow charger for general battery, sulfuric acid accumulates
as a by-product of the chemical reaction, which leads to battery performance
deterioration. In order to charge such a battery turning it into the state of initial
performance, a charger which employs high frequency wave is used to prevent
performance deterioration. As it is also important to check the battery state at this
time to ensure quick charging and prevent performance deterioration, we intend to
look into various methods of checking the battery state, changes in the charger
efficiency, and the difference between a high frequency battery charger and a general
slow battery charger.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
Comparing Evolved Extractive Text Summary Scores of Bidirectional Encoder Rep...University of Maribor
Slides from:
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Track: Artificial Intelligence
https://www.etran.rs/2024/en/home-english/
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Mammalian Pineal Body Structure and Also Functions
Charging sealed lead_acid_batteries
1. Guide to charging Sealed Lead Acid batteries
Sealed lead acid batteries are widely used, but charging them can be a complex process
as Tony Morgan explains:
Charging Sealed Lead Acid (SLA) batteries does not seem a particularly difficult process, but
the hard part in charging an SLA battery is maximising the battery life. Simple constant
current / constant voltage chargers will do the job for a while, but the battery life expectancy
quoted by the manufacturer will be greatly reduced by using non-intelligent chargers like this.
Maximising the life of your SLA battery by using an intelligent charger is not only cost
effective, it is also better for the environment.
Before looking at the different charging techniques it is important to understand the battery
chemistry and what happens during normal charge and discharge cycles.
Typically the positive plates in an SLA battery are made from lead dioxide and the negative
plates from a sponge lead. The electrolyte is usually sulphuric acid mixed with a gelling agent
and is largely absorbed and held by insulating separators between the plates, see Figure 1.
Figure 1: Typical SLA Battery Construction
When an SLA battery is being discharged; the lead (Pb) on the negative plate and the lead
dioxide (PbO2) on the positive plate are converted to lead sulphate (PbSO4). At the same time
the sulphuric acid (H2SO4) is converted to water (H2O).
In a normal charge, the chemical reaction is reversed. The lead sulphate and water are electro-
chemically converted to lead, lead dioxide and sulphuric acid. During a full charge cycle any
gasses produced need to be re-combined in a so called ‘oxygen cycle’. Oxygen is generated at
the positive plates during the latter stages of the charge cycle, this reacts with and partially
discharges in the sponge lead of the negative plates. As charging continues, the oxygen
produced also re-combines with the hydrogen being produced on the negative plate forming
water. With correct and accurate cell voltage control all gasses produced during the charge
2. Guide to charging Sealed Lead Acid batteries
cycle will be re-combined completely into the negative plates and returned to water in the
electrolyte.
If an SLA battery is over-charged, the excess cell voltage will result in the conversion of
electrolyte into large amounts of hydrogen and oxygen gasses which cannot be recombined by
the normal processes. A pressure-release valve will open and vent the excess gas, resulting in
the loss of electrolyte and a loss of capacity.
If the battery is undercharged; the low cell voltage will cause the charge current to diminish to
zero well before full capacity is reached. This will allow some of the lead sulphate produced
during discharge to remain on the plates, where it will crystallise, which also causes a
permanent loss of capacity.
It is also important to remember that SLA batteries have a self discharge rate of
approximately 5% per month. This is less than most other forms of rechargeable batteries, but
has to be considered. Manufacturers recommend recharging when the battery reaches about
70% of its capacity (approximately 2.1 volts per cell). They use this to calculate the maximum
life of the battery, but this is very difficult to implement in a real world application.
So let us look at different charging techniques: -
Constant Voltage Charging: this method is the most commonly used for SLA batteries as
the individual cells tend to share the voltage and equalize the charge between them. It is
important to limit the initial charging current to prevent damage to the battery. However, with
a single fixed voltage, it is impossible to properly balance the requirements of a fast charge
cycle against the danger of overcharge.
Constant Current Charging: this method can be used for a single 2V cell but is not
recommended for charging a number of series connected cells, a battery, at the same time.
This is because some cells will reach full charge before others and it is very difficult to
determine when the battery has reached a fully charged state. If the charge is continued at the
same rate, for any extended period of time, severe overcharge may occur to some cells,
resulting in damage to the battery.
Taper Current Charging: this method is not really recommended for charging SLA batteries
as it can often shorten battery service life due to poor control of the final fully charged
voltage. However, because of the simplicity of the circuit and subsequent low cost, taper
current charging is often used to charge a number of series connected batteries that are subject
to cyclic use. When using this method it is recommended that the charging time is either
limited or that a charging cut-off circuit is incorporated to prevent overcharge.
Two Stage Constant Voltage Charging: this method is a recommended for charging SLA
batteries in a short period of time and then maintaining them in a fully charged float (or
standby) condition.
Each of the above has its advantages and disadvantages, but using a simple charger design
may not be cost effective in the long term. Checking battery condition and replacing batteries
with lost capacity is very costly and environmentally unfriendly. So designing a charger to
maximise the life of the SLA battery is very important.
3. Guide to charging Sealed Lead Acid batteries
Another important factor that has to be considered when charging an SLA battery is
temperature. As the temperature rises, electrochemical activity in a battery increases, so the
charging voltage should be reduced to prevent overcharge. Conversely as temperature falls,
the change voltage should be increased to avoid undercharge.
Using a combination of the constant current charging and two stage constant voltage charging
techniques and also by monitoring the battery terminal voltage and temperature a multi-stage
charge profile can be implemented to reduce stress on the battery while giving the shortest
possible charge time.
Figure 2 shows the multi-stage charge profile used by the Silvertel Ag102 module, for a 6-cell
battery that will achieve this. The upper trace shows the charge voltage and the lower trace
shows the charge current.
Charge Current
Charge Voltage
BatteryVoltage/ChargeCurrent
Charging Time
Constant Current
(Bulk Charge)
Two Stage Constant Voltage
(Absorption Charge)
Pulsed
(Float Charge)
Battery
Capacity
Check
Resume Pulsed
(Float Charge)
Good Battery
Poor Battery
Battery
Capacity
Threshold
~1hr ~2mins
Figure 2: Ag102 Charge Profile
he first part of the multi-stage charge cycle is constant current mode “Bulk Charge”; Ag102
nce the terminal voltage reaches 14.4V; the Ag102 charge cycle automatically moves on to
he final stage of the charge cycle is the “Float Charge”. This can be done by accurately
T
limits this to a maximum of 0.25C Amps (a quarter of the battery capacity), as required by
SLA batteries. For example, if the capacity of the SLA battery being charged is 4Ah, then the
constant current should be limited to 1 Amp. During this stage, the Ag102 monitors the
battery terminal voltage until the terminal voltage reaches 14.4V (2.40V/cell).
O
the second stage “High Absorption Charge”. The Ag102 output changes from constant
current to constant voltage and now monitors the charge current. When the charge current
drops to 0.05C Amps, which is 0.2 Amps for a 4Ah battery, the battery will have recovered
approximately 70-80% of its charge. At this point the Ag102 output voltage reduces to
13.65V (2.275V/cell) - this is the “Low Absorption Charge”. The remaining 20-30% of the
charge is carried out at this lower voltage in order to prevent over-charge. Ag102 will stay in
this mode until the battery is fully charged.
T
maintaining the low absorption voltage level, or as with the Ag102, by providing an
intermittent float charge as shown in Figure 2. These methods ensure that the battery is not
being over-charged, as over-charging will result in battery stress, reducing the battery life.
4. Guide to charging Sealed Lead Acid batteries
ll the above charge voltages are based on an ambient temperature of between 20˚C to 25˚C.
here are limits to the battery operating temperature and SLA battery life is greatly reduced at
ony Morgan
tions Engineer
.com
During the intermittent float charge, Ag102 will periodically check battery capacity, and flag
this information.
A
For the best performance these voltages will need to be temperature compensated by
approximately 4mV/˚C/Cell (reduced at higher temperatures and increased at lower
temperatures). Ag102 has the ability to provide temperature compensation via PTC thermistor
input – the PTC thermistor connects to the battery, and the Ag102 automatically adjusts all
charging voltages to compensate for temperature variances, thus always maintaining optimum
charge performance for the SLA battery – maximising battery life, and minimising charge
times.
T
higher ambient temperatures. For more information on this you will need to refer to the
battery manufacturer’s datasheet.
T
Senior Applica
Silvertel
Newport
South Wales
www.silvertel