Lead acid battery III

Lead-Acid Battery III
Bahtiar Yulianto
August 2017

State of Charge Vs Depth of Discharge

Safety Labeling
IEC 60095-2 Marking of plastic for
recycling are :
Recycling of Lead
Recycling of plastic material
(material code 7 and other to cover
additive to the polypropylene
IEC 60095-1 Six Colored Symbols for
safety labeling

Lead Acid Battery Standard Performance
Electrical Characteristic
• Capacity
- Reserved Capacity Cr,e (minutes)
- 5H Rate/20H Rate Ce (Ah) = t x In
• Cranking Performance Test
- CCA (Cold Cranking Ampere)
- High Rate Discharge Characteristic
• Charge Acceptance ICA (A) = Ce/10
• Water Consumption Test (g/Ah or g/min Cr,e )
• Endurance Test
- Corrosion Test
- Cycling Test
Mechanical Characteristic
• Vibration Resistance
• Strength of Terminal
• Robustness to fastening
• Electrolyte Retention Test

Battery Electrical Performance
• Rated Capacity - Capacity of a Battery is denoted by Ampere Hour at a given rate
of discharge up to a given end cutoff voltage at a given temperature. As per JIS
(D5301) batteries are rated at 5 Hrs rate of discharge up to 10.5 volts at 25° C.
• Reserve Capacity Rating - Capacity expressed as the number of minutes which a
new fully charged battery at 25°C can be continuously discharged at 25 amperes
and maintain a terminal voltage equal to or higher than 10.5 volts per cell. RC =
((C20+133.3)2-17778) / 208.3
• Cold Cranking Amperes (CCA)- Cold Cranking Performance rating is the discharge
load in amperes which a new fully charged battery at -18°C can deliver. This is to
ensure that the battery can deliver the required Cranking Amps in the cold climate.
• Cranking Amperes (CA) - Cranking Performance rating is the discharge load in
amperes which a new fully charged battery at 0°C can deliver. This is to ensure that
the battery can deliver the required Cranking Amps in Hot climate.
• C20-HOUR CAPACITY The 20-hour capacity is the current in amperes which a 12
volt battery can supply for a period of 20 Hours while maintaining a voltage at
greater than 10.5 volts @ 25° C
• C5-HOUR CAPACITY The 5-hour rate capacity is the current in amperes which a 12
volt battery can supply for a period of 5 Hours, while maintaining a voltage at
greater than 10.5 volts @ 25° C

The difference between Conventional Batteries, Hybrid
Batteries and MF Batteries
Description
Conventional Batteries-
Dry charged
Hybrid Batteries-
Dry charged
MF Batteries
Plate Lead Alloy
Positive and negative plates of Lead
antimony alloy
Positive plates of Lead antimony and
negative of Lead calcium alloy
Positive and negative plates of Lead
Calcium Alloy
Activation
To be activated with electrolyte.
Ideally 20 mins rest to be provided
for propoer activation after
electrolyte filling. Electrolyte of
correct sp. gr and quality to be filled.
To be activated with electrolyte.
Ideally 20 mins rest to be provided
for propoer activation after
electrolyte filling. Electrolyte of
correct sp. gr and quality to be filled.
No need of Activation since supplied
in filled and charged condition from
the Factory.
Storage
Up to two years before activation
with electrolyte. However the
battery to be stored in cool and dry
place.Not effected by Self Discharge
when stored in dry condition.
Up to two years before activation
with electrolyte. However the
battery to be stored in cool and dry
place.Not effected by Self Discharge
when stored in dry condition.
3-4 Months at an Average ambient
Temp of 35 Deg C. Refer to the
Technical write up for details of self
discharge.
Electrolyte accessibility and
electrolyte Top up (Adding
Distilled Water)
Accessible electrolyte, Top up
frequency once 2-3 Months. This
may varry depending on Alternator
condition, driving pattern and
ambient temp.
Accessible electrolyte, Top up
frequency once 4-6 Months. This
may varry depending on Alternator
condition, driving pattern and
ambient temp.
Electrolyte not accessible.Doesn't
require top up in its entire service
period.
Deep discharge endurance
(when the battery is abused)
Very Good Very Good Good
Resistance to overcharging
(when the battery is abused)
Very Good Very Good Good

Lagging cells in lead acid batteries
NZ Best Batteries Service Ltd.
All the cells in a battery should always remain in the same state of charge or discharge.
lf only one of the cells in a battery will discharge earlier than the others, the efficiency of
the battery will be determined by this cell.
Such a cell limits the capacity of the battery because during discharge its voltage will
drop to the final value ahead of any of the other cells.
If the discharge of a battery is continued after the voltage of such a lagging cell has
dropped to the final permissible value, this cell may rather quickly discharge to zero,
while the other cells in the battery still have a voltage higher than the final value and
remain in a state of charge. In this case, the discharge current of cells that retain their
charge, in passing through the lagging cell, will begin to act on the lagging - cell
plates like a charging current. As a result, lead dioxide will be formed on the negative
plates of the lagging cell, while lead forms on the positive plates. The final result will
be a reversal of polarity of the plates, following which the voltage of the battery will
drop considerably. This makes it clear why the discharge of a battery must be
stopped as soon as the voltage of any of the cells has dropped to the limited final
value.

The lagging of a cell may be identified by the following signs: the density of the electrolyte
in a cell during a discharge of the battery is found to be lower than that in the other
cells, and does not remain within a permissible limit; the voltage of the cell at the end
of a charge is the lowest in value, while the temperature of the electrolyte during the
charge may rise higher than that in the other cells.
During a discharge of the battery, the rapid drop in voltage of the lagging cell will limit the
capacity of the battery. However, if the ampere - hours obtained during the control
discharge are close to the guaranteed value, or to the ampere-hours obtained during
the previous control discharge, the is considered is fit for service, although the
discharge was interrupted because the voltage of only one cell has dropped to its
final value. In a battery that is fully fit for service, the difference between the voltages
of the cells at the time a discharge is discontinued will not exceed 0.2 V.
Timely detection and the remedying of lagging cells can only be attained when the
density of the electrolyte is closely watched.
The density of the electrolyte in the cells after the latter are brought up to a working
condition is corrected so that it will not differ in any given battery by more than
5kg/m3 from the established value for the given climatic conditions.

If during a routine charge of the battery all the usual signs of the end of the charge are
observed (constant electrolyte density and voltage, and abundant gassing in all cells
over a period of two hours), but the density of the electrolyte in some of the cells
remains less than is normally required by more than 10 kg/m3, it is necessary lo
discontinue the charge for one hour and then renew it for another two hours. lf the
density of the electrolyte in the cells after this rises to within the limits of 10 kg/m3
from the required value, the battery may be put back into service. However, if the
electrolyte density in some of the cells still remains too low, it can be considered that
these are lagging cells. Such batteries must be subjected lo several cycles of charge
and discharge to more completely convert the lead sulfate into active materials, and
also decide on the necessity for any repairs.
If several batteries are operated on some given unit or machine and are connected in
parallel or in series, it is important to closely watch that all of the cells in these
batteries remain in the same condition.
When the capacity of the cells in one of the series-connected batteries is too low, the
duration of battery discharge is limited by the capacity of the lagging cells. If the
discharge is continued it is possible that the lagging cells may have their polarity
reversed.
In this connection it should be noted that the danger of polarity reversal is especially
great when operating a repaired battery which, along with the old cells, contains cells
provided with new sets of plates.

SULFATION PLATES IN LEAD-ACID BATTERIES
• As is known, when a cell is discharged lead sulfate is formed on the positive and
negative plates. This sulfate, during the subsequent charge of the cell, will readily be
converted into active materials. The trouble called “sulfation of the plates" results
from a certain discharged condition of the plates due to which they become covered
with a layer of less-soluble lead sulfate which does not readily revert to an active
material within the usual period of time required with a charging current of normal
value.
• The lead sulfate which appears in conditions of normal discharge consists of small
crystals which are uniformly distributed and form a porous mass that is highly
conductive. When a cell containing such a sulfate is charged again, the sulfate is
readily converted into lead dioxide and lead. However, if the discharge of the cell is
carried out too deeply, the active material of the plates is almost completely
converted into lead sulfate which, in some cases, changes over from a small-crystal
to a large-crystal structure.

• When this is so, if organic surface - active agents are present in the cell, adsorption
of these substances will take place on the surfaces of the lead sulfate crystals on the
negative plates. This will lower the rate at which the crystals will be able to go into
solution. It was found that the internal electrical resistance of the active-material layer
increases abruptly in such cases. The sulfate particles completely cover the
conductive active material and thus stop the passage of current through the plate.
The potential at which gassing starts during charging also changes. The conversion
of the portion of the sulfate carrying a film of adsorbed substances to lead dioxide
and lead becomes impossible in these conditions, and the cell loses part of its
capacity, and on very heavy sulfation may lose almost all its capacity.

The causes that lead to the formation large crystals of lead sulfate may be: systematic,
excessively deep discharges of the cells; regular undercharging of the cells; cells are
left for long periods in either the semi-charged or semi-discharged condition; low level
of the electrolyte in the cells.
The signs of sulfation of the plates are:
1. a decrease in cell capacity. The capacity in most cases is limited by the negative
electrode. When this is so, the potential of the negative electrode on discharge at the
10-hour rate, after 5 to 8 hours, reaches the value of 0.4 to 0.6 V relative to a
cadmium test electrode;
2. an electrolyte density less than the normal value;
3. a high cell voltage at the beginning and end of charge (up to 3 V). The potential of the
negative electrode rapidly acquires a negative value after the charge begins;
4. gassing begins much earlier during the charge of the cell;

5. the positive plates have an abnormal colour (light brown, sometimes with white spots);
6. an abnormal condition of the negative plates. The active material of the negative plates
has increased in volume and is seen to bulge from the pockets. A white deposit of
sulfate is usually visible on the negative plates.
There are several methods of restoring the capacity of sulfated cells: a long charge of the
cells with a small current; charging of the cells in distilled water; discharging of the
cells with a small current; charging with a heavy current for 1 to 2 hours; cycling with
polarity reversing.

SHORT CIRCUITS IN LEAD - ACID BATTERIES
• Short circuits may occur within a cell as a result of damage to one or several
separators between the positive and negative plates; because of excess
accumulation of sediment in the bottom of the cell container, or because of “treeing”,
the growth of dendrites in the lead sediment. Dendrite formation may be due to two
causes: (1) the loosened particles of the active material raised by the gassing during
a charge settle on top of the plates and form bridges over the separators; (2) the grid
material contains certain constituents, cadmium, for example, that facilitate the
formation of dendrites at the sides and bottom of the plates.
• Grids of pure lead also have a tendency to form dendrites in the direction from the
negative to the positive plates. The presence of antimony in the grid material
somewhat neutralizes this tendency. The kind of dendrite formation that may occur is
influenced by the surface - active agents that find their way in the expanders included
in the negative-plate active material. The signs of short-circuits inside the battery are:
continuous decrease in electrolyte density, notwithstanding the fact that the battery is
receiving a normal charge; rapid loss of capacity after a full charge; a low open -
circuit voltage.

SHORT CIRCUITS IN LEAD -ACID BATTERIES
To remedy this condition it is necessary
to dismantle the cells, remove all the
sediment accumulated in the bottom,
wash out the container, replace the old
separators and remove any dendrites
from the plate.
Microstructure of (a) Pbe3.5 wt% Sb; and (b) Pbe11.7 wt% Sb alloys [17]. White dendrites
are a-Pb particles.

Corrosion of positive plate grids in lead-acid batteries
• While a cell is being charged, the lead sulfate which has been formed directly from
the grid material as a result of local action is also converted into lead dioxide. This
process, called the forming of the grid, although it somewhat weakens the grid, does
not shorten its normal service life.
• Premature destruction of the positive plate grid takes place when the lead dioxide
becomes separated from the lead grid surface and the electrolyte fills the space
between them.
• Long-continued overcharging causes oxidation of the positive grid, reduces the cross-
section of the grid bars and eventually brings about complete destruction of the grids.
• It should be borne in mind that the premature forming process may become
accelerated if the charge is conducted at a temperature exceeding 45°C.
• The grids of positive plates that have been subjected to this “over forming” may easily
be detected by checking the colour of their fracture. If the fracture is seen to have a
brown colour, it is an indication that the grid lead has become converted to lead
dioxide. Such grids are brittle, and the positive plates may be easily broken by hand.

Corrosion of positive plate grids in lead-acid batteries
• Contamination of the electrolyte by organic acids brings about rapid destruction of the
grids; particularly heavy corrosion is caused by acetic acid. Chloride contamination of
the electrolyte also causes corrosion of the grid.
• A sign of grid corrosion is a reduced number of ampere hours obtained from the
battery on discharge at the 10 hour rate. The capacity is always limited by the positive
electrode.
• Cells containing plates destroyed by corrosion are no longer fit for service. Usually,
corrosion of the grids is a sign of long service of the given cells.

Bulging and buckling of positive plates
• If the service conditions have been abnormal, the positive plates will be found to
change in size, buckling will also be observed. These are the result of lack of
uniformity in the rates of charging and discharging over the entire area of the plates.
Buckling usually takes place during charges with currents of high density, short
circuits, during overcharges, and because of failure to hold the temperature within
permissible limits during a charge. The growth in size of the plates is due to gradual
corrosion of the grid because the lead dioxide resulting from corrosion occupies a
larger space than the grid lead from which it is formed. There are sometimes cases
when the plates change their dimensions as much as several centimetres.

Shedding of the positive active material
• The shedding of the active material from the positive plates is one
of the causes of premature failure in service of lead-acid cells. The
essence of this trouble is that tiny crystals and grains of lead
dioxide smaller than 0.1 micron (one tenth of one thousandth of a
millimetre) become dislodged from the plates. The shedding mainly
takes place at the end of a charge and the beginning of a
discharge. Till recently, the explanation was that shedding is due to:
volumetric variations of the material on the electrode during its
operation, free gassing at the electrode during overcharges, and
operation of the cells at high temperatures.
• The shedding of active material from the positive plates has been
investigated by many electrochemists. It has been established that
the temperature of the electrolyte and current density during the
charge do not have an important bearing on the service life of the
active material. It is the conditions of discharge that essentially
affect the service life of the active materials.

Shedding of the positive active material
• Increase in concentration of the electrolyte, reduction in temperature, and increase in
current density during discharge greatly attribute to the rate of destruction of the
active material.
• For example, a reduction in the density of the electrolyte from 1,200 to 1,100 kg/m3
increases the service life of the active material some 8 to 10 times, and is the most
essential factor. A three-fold reduction in the discharge current density lengthens the
service life about 50 per cent, while an increase in temperature from 25 to 50⁰C on
discharge increases the service life of the active material more than 2 to 2.5 times.
• It has been shown recently that the shedding of the active material is the result of the
appearance of crystals of lead dioxide with a different form of crystalline structure.
• One of the ways of increasing the service life of the active material is to introduce into
the cell, after it has been in operation for 70 to 100 per cent of its guaranteed service
life, about 0.5 to 1.0 per cent of a suitable reducing agent, for example,
hydroxylamine sulfate (suggested by I. I. Koval). The purpose these agents serve is
chemical reduction of lead dioxide to lead sulfate, from which, during a subsequent
charge, is formed an active material which possesses a strong structure. However,
this method has yet to be more widely tested.

Contamination of the electrolyte
• Contamination of the electrolyte by impurities, especially
by salts of the metals and organic substances, will greatly
accelerate corrosion of the grids. The measures that must be
taken to prevent contamination are simple and amount to
preparing the electrolyte only from battery-grade sulfuric acid
and distilled water.
• In those cases when sulfuric acid of the technical grade is
accidentally used to prepare the electrolyte, the active
material, as well as the grids of the positive plates, due to
presence in this acid of various impurities, are often
destroyed even after the first charge.
• This also occurs in those cases when, to prevent freezing of
the electrolyte, alcohol is added to it.
• Only use distilled water which is known to be pure to prepare
the electrolyte and never use drinking water, it always
contains compounds of iron, chlorides, nitrates (salts of nitric
acid) and other substances which may destroy the active
material and plate grids and lead to an increased self-
discharge of the cells.

Increased self-discharge
• Discharge of a cell which takes place while it remains open-circuited is called self-
discharge.
• When batteries are in service, cases arise where normal and increased rates of self-
discharge may be observed.
• A self-discharge, though inevitable, should not exceed a rate established as normal.
• Normal self-discharge of a cell takes place due to several causes. The grid of the
positive plate is not fully in contact with the lead dioxide and the electrolyte occupies
the spaces left free between the grid and the lead dioxide. Because of this a
difference in potential is created between the lead grid and lead dioxide, or in other
words, a local cell which is in a state of discharge is formed.
• The discharge of this local cell is accompanied by conversion of the active material
into lead sulfate and thus hampers further discharge of the local cell. This explains
why there is the considerable decrease in self-discharge from day to day when the
battery is allowed to stand idle.
• The negative plate grid, which is made of an alloy of lead with antimony, and the
negative-plate active material containing sponge lead, represent two electrodes
between which a difference in potential that causes self-discharge is created.

• Metal impurities which can only be removed with great difficulty and are always
present in the materials from which the plates are made, and the impurities contained
by the electrolyte, are also causes of normal self-discharge. Another cause of normal
self-discharge is that the density of the electrolyte at the bottom of the plates is
always a little greater than that at the top of the plates.
• Since the potential is dependent on the density of the electrolyte, a potential
difference is created between the upper and lower parts of the plates, this leading to
self-discharge.
• If a film of electrolyte appears on the internal surface of the cell cover it forms a
contact bridge between the terminal post of the groups of plates; this also may be a
cause of self-discharge.
• Batteries in which separators of mipor or miplast are used, when left to stand idle for
30 days, should have a normal self-discharge of not more than 21 per cent of their 10
hour rate capacity.
• Let us consider the causes of excessive self-discharge.

• During careless filling of electrolyte into the cell and violent gassing while charging,
the external surface of the cell may become wetted by spilt electrolyte. This will
greatly increase the rate of self-discharge. The rate of this self-discharge (or leakage)
in some cases exceeds 5 to 10 per cent of battery capacity per day, due te which the
battery may be discharged in 10 to 20 days.
• This form of self-discharge may be detected with a voltmeter. One lead of the
voltmeter is tightly held against the battery terminal, the other is held against the
surface of the battery where traces of spilt electrolyte may remain. If the pointer of the
voltmeter deviates from zero, it shows the existence of a current path for self-
discharge.

Lead-Acid Cell and Battery Troubles and Their Remedies
PROBLEM CAUSE REMEDY
1. The battery has low capacity 1. Plates worn because of long service Replace battery
2. Shedding of active material from
positive plates
Replace battery
3. Systematic undercharge Carry out a long overcharge cycle
(equalize)
4. Contamination of electrolyte Replace electrolyte, wash out cells
5. Sulfation of plates Carry out desulfation charging
6. Leakage of current, heavy self
discharge
Check cell containers, clean and dry the
cells
7. Battery is used at a low temperature Lag the battery to reduce the loss of heat,
slightly increase the density of electrolyte
2. No voltage or practicly no voltage
across cell terminals
Short circuit, high leakage of current,
sulfation
Carry out desulfation charge, if does not
help replace the battery
3. Abnormal increase in
temperature of electrolyte during
charging
1. Excessive charging current Discontinue charge and decrease charging
current
2. Short circuit in cell Replace battery
3. Heavy sulfation Carry out desulfation charge
4. The electrolyte has abnormal
colour, cell contains much sediment
Shedding of active mass Remove shedding by washing. Charge and
discharge with normal current
5. Density of electrolyte is low at
the end of charge, no gassing is
observed
Short circuit in cell Replace battery
6. Abnormal and premature gassing
during charging
1. Sulfation Carry out a desulfation charge
2. Large charging current Change to normal value of current
3. Charge is carried out at too low
temperature
Warm up battery
7. Heavy gasing during discharge Dirty electrolyte Change electrolyte
8. Abnormal colour of plates,
presence of white spots on top parts
of plates
1.1. Sulfation Carry out desulfation charge
2. Contamination of electrolyte Change electrolyte, wash out cells
3. Excessive length of service Replace battery
9. Destruction of positive plates 1. Long term overcharges Adjust charging rate of the cell to avoid
overcharging
2. Contamination of electrolyte Change electrolyte, wash out the cells
3. Excessive length of service Replace the battery
Electrolyte is contaminated by chlorides
or acids
Check and change electrolyte, wash out
the cells

Cycling
(Kevin R Sullivan, Professor of Automotive Technology Skyline College)
The battery stores electricity in the form of chemical energy.
Through a chemical reaction process the battery creates and
releases electricity as needed by the electrical system or
devices. Since the battery loses its chemical energy in this
process, the battery must be recharged by the alternator.
By reversing electrical current flow through the battery chemical
process is reversed, thus charging the battery. The cycle of
discharging and charging is repeated continuously and is called
“battery cycling”.

Deep Cycling
(Kevin R Sullivan, Professor of Automotive Technology Skyline College)
Although batteries do cycle continuously, they do not cycle deeply.
Deep cycling is when the battery is completely discharged before
recharge.
Automotive batteries are not designed as deep cycle batteries.
Automotive batteries are designed to be fully charged when
starting the car, after starting the vehicle, the lost charge is
replaced by the alternator. So the battery remains fully charged.
Deep cycling an automotive battery will cause damage to the
plates and shorter battery life.
Marine or golf cart batteries (Deep Cycle Batteries) on the other
hand are designed to be completely discharged before
recharging. Because charging cause excessive heat which can
warp the plate, thicker and stronger plate grids are used. Normal
automotive batteries are not designed for repeated deep cycling
and use thinner plates.

Battery Performance
1. Charging efficiency is high.
2. The battery can save the electricity fully.
3. Discharging power is high.
1. Charging efficiency is low.
2. The battery cannot save the electricity fully .
3. Discharging power is low.
SSRLChemicals.com

Water Loss in VRLA
(Chalasani S C Bose)
 Inefficient oxygen recombination (H2OIERC)
2H20  3O2 + 4H+ + 4e-
 Positive grid corrosion (H2Ocorr)
Pb + 2H20  PbO2 + 4H+ + 4e-
4H+ + 4e-  2H2O
 Water permeation through the battery container and cover
(H2OPerm)
H2O Total = H2OIERC + H2Ocorr + H2OPerm
Water loss due to positive grid corrosion does not result in
equivalent weight loss since Pb consumes oxygen from water to
form heavier PbO2.
Weight loss H2O = Weight Loss net + Weight Loss gain corr

Premature Capacity Loss in VRLA
(GJ May – FOCUS Consulting Elsevier 2009)
PCL-1 is a grid/positive active material effect where a passivation layer is formed at the
grid/active material interface. It may be overcome by the use of Pb–Ca alloys or pure
lead with additions of tin, which avoids the formation of insulating layers at the interface
as for VRLA gel cells.
PCL-2 is an active material effect where connective lead dioxide particles in the positive
active mass become partially disconnected through the formation of areas of lead sulfate
that are not recharged. It may be avoided by high compression of the separator so as to
keep the active material under compression.
PCL-3 is an effect where the negative plate is not sufficiently charged and becomes
sulfated resulting in permanent capacity loss.

REFERENCE
– Kevin R Sullivan, Professor of Automotive Technology Skyline College
– NZ Best Batteries Service Ltd
– Curing and Formation, R Wagner, MOLL Accu Elsevier 2009
– International Journal of Electrochemical Science Vol 6, 91-102 (2011)
– Journal of power source 85 (2000) 117-130.
– Dr. Reiner Kiessling, Lead Acid Battery Formation Techniques
– Detchko Pavlov - Lead-Acid Batteries - Science and Technology (2011)
– D Berndt – Electrochemical Energy Storage (2003)
– J.P .Carr and N.A. Hampson – The lead dioxide electrode (1972)

Lead acid battery III

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to Lead acid battery III

Similar to Lead acid battery III (20)

Recently uploaded

Recently uploaded (19)

Lead acid battery III