Simple explanations for beginners.

1. 1
BATTERIES - SIMPLE NOTES
KEY TERMS
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Anode
—A positively charged electrode.
Battery
—A battery is a container, or group of containers, holding
electrodes and an electrolyte for producing electric current by
chemical reaction and storing energy. The individual containers
are called "cells". Batteries produce direct current (DC).
Cathode
—A negatively charged electrode.
Direct current (DC)
—Electrical current that always flows in the same direction.
Electrode
—The conductor by which electricity enters or leaves a galvanic
cell.
Electrolyte
—The medium of ion transfer between anode and cathode within
the cell. Usually liquid or paste that is either acidic or basic.
Galvanic cell
—Combination of electrodes separated by electrolyte capable of
producing electric energy by electrochemical action.

2. 2
Primary cell
—A galvanic cell designed to deliver its rated capacity once and
then be discarded.
Secondary cell
—A galvanic cell designed for reconstitution of power by
accepting electrical power from an outside source. If two metals
are immersed in an aqueous solution that can conduct
electricity (electrolyte), they will have different tendencies to
dissolve in the solution. A difference in voltage arises because
one of the metals appears positive or negative relative to the
other. The combination of two metals (electrodes) in an aqueous
solution for the purpose of producing electrical energy from
chemical energy is referred to as a galvanic cell. A battery is a
set of two or more galvanic cells connected in a series or
parallel. (Though not strictly correct usage, a single galvanic
cell is also frequently referred to as a battery.) Each cell
contains two types of electrodes, an anode (positive electrode)
and a cathode (negative electrode), that together provide and
absorb electrons with sufficient voltage (electromotive force) to
operate useful machines or devices. The electromotive force for
every cell reaction that is well understood can be calculated, and
the voltage of an actual cell will not exceed this value.

3. 3
Metals and other conductors can be arranged in an
electrochemical, or electromotive, series in which each
conductor's tendency to lose electrons relative to another
conductor is ranked. The higher the electric potential, the more
likely the metal is to appear electrically positive. In terms of
electric potential, carbon has a higher potential than gold, gold a
higher potential than silver; this sequence is followed in order by
copper, tin, lead, iron, and zinc.
Moderate energy primary cells
Zinc/manganese dioxide systems
The cell developed by Georges LeClanche in 1866 used
inexpensive, readily available ingredients. It therefore quickly
became a commercial success. The anode is a zinc alloy sheet
or cup (the alloy contains small amounts of lead, cadmium, and
mercury). The electrolyte is an aqueous solution of zinc chloride
with solid ammonium chloride present. The cathode is
manganese dioxide blended with either graphite or acetylene
black to conduct electrons to the oxide. The system is relatively
tolerant of many impurities. These cells are used in barricade
flashers, flashlights, garage door openers, lanterns, pen lights,
radios, small lighted toys and novelties, and in others.
The zinc chloride cell without ammonium chloride was patented in

4. 4
1899, but the technology from commercially producing such cells
did not prove practical until about 70 years later. Currently zinc
chloride cells deliver more than seven times the energy density
of the original LeClanche cell. This cell is used in same
applications as the LeClanche cell.
Zinc/manganese dioxide alkaline cells
The zinc/manganese dioxide alkaline cell's anode consists of
finely divided zinc. The cathode is a highly compacted mixture of
very pure manganese dioxide and graphite. The cells operate with
higher efficiency than the zinc chloride or LeClanche cells at
temperatures below 32°F (0°C). Manganese/manganese dioxide
cells have much higher energy densities than zinc chloride
systems. Cylindrical batteries are used in radios, shavers,
electronic flash, movie cameras, tape recorders, television sets,
cassette players, clocks, and camera motor drives. Miniature
batteries are used in calculators, toys, clocks, watches, and
cameras.
Medium to high energy primary cells
Mercuric oxide/zinc cells
Mercuric oxide/zinc cells use alkaline electrolytes and are
frequently used in small button cells. The cell has about five to
eight times the energy density available in the LeClanche cell and
four times that in an alkaline manganese dioxide/zinc cell. The

5. 5
cell provides a very reliable voltage, and is used as a standard
reference cell. These cells are used for walkie-talkies, hearing
aids, watches, calculators, microphones, and cameras.
Silver oxide/zinc cells
Silver oxide/zinc cells use cellophane separators to keep the
silver from dissolving and the cells from self discharging. The
system is very popular with makers of hearing aids and watches
because the high conductivity of the silver cathode reaction
product gives the cell a very constant voltage to the end of its life.
These cells are also used for reference voltage sources, cameras,
instruments, watches, and calculators.
Lithium (nonaqueous electrolyte) cells
Lithium/iron sulfide cells take advantage of the high
electrochemical potential of lithium and low cost of iron sulfide.
The high reactivity of lithium with water requires that the cells use
a nonaqueous electrolyte from which water is removed to levels of
50 ppm. Lithium/manganese dioxide cells are slowly increasing in
commercial importance. The voltage provides a high energy
density, and the materials are readily available and relatively
inexpensive. Lithium/copper monofluoride cells are used
extensively in cameras and smaller devices. They provide high
voltage, high power density, long shelf life, and good low
temperature performance.

6. 6
Lithium/ thionyl chloride cells have very high energy densities and
power densities. The cells also function better at lower
temperatures than do other common cells.
Lithium/ sulphur cells are used for cold weather use and in
emergency power units.
Air-depolarized cells
Zinc/air cells are high energy can be obtained in a galvanic cell by
using the oxygen of air as a "liquid" cathode material with an
anode such as zinc. If the oxygen is reduced in the part of the cell
designed for that purpose and prevented from reaching the
anode, the cell can hold much more anode and electrolyte
volume.
Aluminum/air cells have difficulty protecting the aluminum from
the electrolyte during storage. Despite much research on this type
of cell, aluminum/air cells are not in much current use.
Secondary cells
Secondary cells are designed so that the power withdrawn can be
replaced by connecting the cell to an outside source of direct
current power. The chemical reactions are reversed by suitably
applying voltage and current in the direction opposite to the
original discharge.

7. 7
Moderate energy storage cells
Lead secondary cells
The lead/acid rechargeable battery system has been in use since
the mid-1950s. It is the most widely used rechargeable portable
power source. Reasons for the success of this system have
included: great flexibility in delivery currents; good cycle life with
high reliability over hundreds of cycles; low cost; relatively good
shelf life; high cell voltages; ease of casting, welding, and
recovery of lead.
The chief disadvantage of this battery is its high weight.
Nickel electrode cells with alkaline electrolytes
Nickel/cadmium cells provide portable rechargeable power
sources for garden, household tools, and appliance use. The
system carries exceptionally high currents at relatively constant
voltage. The cells are, however, relatively expensive. These cells
are used for portable hand tools and appliances, shavers,
toothbrushes, photoflash equipment, tape recorders, radios,
television sets, cassette players and recorders, calculators,
personal pagers, and laptop computers.
Alkaline zinc/manganese dioxide cells
Alkaline zinc/manganese dioxide systems been developed and
used as special batteries for television sets and certain portable
tools or radios.

8. 8
High energy storage batteries
Silver/zinc cells
Silver/zinc cells are expensive. They are chiefly used when high
power density, good cycling efficiency, and low weight and
volume are critical, and where poorer cycle life and cost can be
tolerated. They are used in primarily four areas: under water, on
the ground, in the atmosphere, and in space.
Lithium secondary cells
Lithium secondary cells are attractive because of their high
energy densities.
Sodium/sulfur systems
Sodium/sulfur systems are high-temperature batteries that
operate well even at 177°F (80.6°C).
See also Cell, electrochemical; Electricity; Electrical conductivity;
Electric conductor.
Resources
Books
Macaulay, David. The New Way Things Work. Boston: Houghton
Mifflin Company, 1998.
Meyers, Robert A., Encyclopedia of Physics Science and
Technology. New York, NY: Academic Press, Inc., 1992.

9. 9
Sierra Nevada Airstreams - Owner's Guide - Understanding
Preparing - Driving - Living - Touring - Maintaining - Understanding -
Recreation with vehicles in the Sierra Nevada and American Great
Basin areas
Understanding Battery Charging
After you take electricity out of a battery, you need to get electricity back in
so you can use it once more. This is the process of charging the battery.
You should only charge batteries designed for re-use. Most RV lead acid
batteries are designed for re-use. Carbon zinc flashlight batteries are an
example of a battery that is not safe to charge. Charging batteries means
reversing a chemical reaction by running an electrical current through some
materials. This generates heat due to the resistance of the materials to
electricity flow and chemical reactions. The chemical reactions may also
produce products that can be hazardous. If a battery is not designed for
charging, attempting to charge may can cause its container to burst or even
explode spreading caustic material on anything nearby.
Discharge considerations
Batteries should not be discharged too fast or too far. Taking electricity out
of a battery or putting electricity back into a battery requires both chemical
and electrical processes. Chemical processes require that two (or more)
materials come into contact with each other and change into something
else. Electrical processes move electrons through materials. Neither
process is 100% efficient and both suffer degradation through use cycles.

10. 10
"If you operate your house bank between 50% to 85% state of charge, as
many experts recommend, and charge once daily, you should be able to
return the 35% of battery capacity by [properly charging] for slightly over an
hour." (West Marine)
A twelve volt battery is about half discharged at 12.2 volts and this is about
as far as you should discharge it in normal use.
Charging versus maintenance
It is one thing to get a battery charged and yet another to keep it charged.
When batteries sit, they will slowly discharge even if there is nothing
connected to them. This means that battery maintenance needs to
accommodate three states. One is usage. Another is charging. And the
third is keeping the charge. Each of these states has its own particular
demands on a battery charger.
If a battery charger is left on-line when appliances are connected to the
battery (the usage sate), you need to be careful that the charger is
designed so as not to damage the appliances. This characteristic is one of
the primary considerations of an RV converter.
The state that kills most batteries is that of keeping the charge when the
battery is not otherwise in use. A trickle charger (low current charger at a
float voltage) can prevent discharge. The other problem is called sulfation (
see Az Wind Sun -
http://www.windsun.com/Batteries/battery_desulfator.htm ) which happens
when a battery isn't stirred up every now and then.

11. 11
Maintenance device brands: Battery Pal, Battery Tender,
Basic Charging Devices
The most basic type of battery charger is called a "constant voltage, current
limited" type. This type of battery charger can be made with only three
components. A transformer converts house voltage to battery voltage. A
rectifier converts the household alternating current (AC) to battery direct
current (DC). A resistor limits the current as a protection for both the
charger and the battery. They are very good at providing a bulk charge but
not so good at finishing a charge or maintaining a battery.
All a basic charging device needs to know about its battery is its voltage.
This knowledge is usually built into the design of the device.
Source: most 'under $100' automotive battery chargers at department or
automotive stores.
RV Converters
The converter in an RV is intended to provide a nominal battery voltage for
RV lights and appliances as a first priority. Charging batteries is a second
priority. These are similar to basic charging devices except that they may
have some extra protections as well as some filtering to minimize noise and
interference in RV appliances and to prevent excess voltage.
A converter should not be confused with an inverter. The 'con' takes AC
and converts it to DC. The 'in' takes DC and inverts it to AC so you can run
household appliances when not connected to the AC grid. Many of the
better quality inverters will include a multi-stage battery charger as well.

12. 12
RV Converters are not good at battery maintenance so, if yours is left
connected for any period of time, be sure to closely monitor battery water
level.
Manufacturers: Intelli-Power, Magnetek,
Multi-stage Charging Devices
Somewhat intelligent, these battery chargers will tailor charging current for
rapid restoration of battery capacity. They incorporate controls to separate
battery charging into several stages. These stages can include the
following.
1. Bulk - full current to bring battery voltage up - usually ends when the
voltage gets up to a pre-determined point.
2. Absorption or acceptance - maintain a rather high fixed voltage to
complete the battery charge - usually ends when the current gets
down to a pre-determined point.
3. Float - a reduced constant voltage to provide maintenance without
boiling off electrolyte.
4. Equalization - a controlled periodic overcharge to equalize and
balance the battery cells and reverse the build up of chemical effects
resulting from a battery sitting for a long period.
A multi-stage charger needs to know not only the voltage of the battery to
be charged but also its charging current limitations. The charging current
for lead acid batteries is usually assumed to be one fifth of its amp hour
capacity. (e.g. a 100 amp hour battery should be charged at no more than
20 amps).

13. 13
Brands: Truecharge, Charge Pro, Intelli-Power with Charge Wizard,
Intelligent Charging Devices
Intelligent devices have a means to learn about the battery so charge
restoration can be carefully controlled for a specific battery and conditions.
These are often programmed with switches and dials and may have a
temperature probe in order to consider battery temperature while charging.
The programming tells the device what kind of battery (AGM, Gel Cel, Wet
Cell, NiCd, etc) it is charging and the battery capacity. With this knowledge,
they can carefully shape charging characteristics for fastest charging and
best battery life.
Automotive Alternators
The alternators in common car systems are essentially a basic charging
device. They have some temperature compensation to adjust charging
voltage for under the hood temperatures but are otherwise constant voltage
current limited devices. The common problems with these types of
chargers is not at issue because automobiles are not operated
continuously. The downside is that, if you leave the vehicle unused for a
while, you may need to pay attention to maintenance charging and
sulfation.
Resources
Sierra Nevada Airstreams
 commerce page for links to suppliers and online stores.

14. 14
 Configuration page to learn about discharge rates and battery
capacity
 Batteries page to learn about types of batteries
 Electricity, Electrical, and Energy pages to learn about volts, amps,
joules, watts and similar concepts.
Other resources:
 VDC Electronics - which is best?
http://www.vdcelectronics.com/which_is_the_best_battery.htm -
 Battery care answers - http://zing.ncsl.nist.gov/nist-
icv/battery/battery/BatteryCare2.html -
 Gulf Stream Coach Battery Basics -
http://www.gulfstreamcoach.com/tidbitsstuff/vol13no2.htm -
 Interstate Batteries charging tips -
http://www.hibdons.com/interbatt.htm -
 AM Solar - http://www.amsolar.com/batteries.html -
 William Darden's Battery FAQ - http://www.batteryfaq.org/ -
 Battery Tender - http://www.batterytender.com/ - they explain the
basis for why their product does what it does. A lot of good
information.
 Store 4 Power - http://www.store4power.com/index.asp? - sells
chargers and inverters
 Witch Well Energy battery products -
http://www.witchwellenergy.com/Merchant2/4.13/00000001/catalog/c
7.html - water recover caps and other accessories for battery
maintenance

15. 15
 RV Solar battery page - http://www.rvsolar.com/batteries.htm -
voltage chart and other information
 Exide - common marine battery questions -
http://www.exide.co.nz/faqs/marine.htm - from the mfg!
 A tutorial - http://www.4unique.com/battery/battery_tutorial.htm -
some links as well as definitions and "do's and don'ts"
 ETA Engineering care and maintenance guide -
http://www.etaengineering.com/battmaint.html - good summary or
checklist.
 Monaco Coach tips -
http://www.monacocoach.com/service/techtips/11_28_02.html - don't
exceed voltages
 Luxmi Batteries - http://www.luxmibattery.com/facts.htm - causes of
failure

16. 16
Sierra Nevada Airstreams: Destinations - Owners - Community - Family -
Memories - Education - WBCCI Unit - Quicksand - Commerce
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17. 17
SBS produces a complete selection of lead
acid flooded, VRLA, NiCad & specialty
batteries for a variety of reserve, stationary, cirtical & motive power
applications. SBS has developed numerous intermediate sizes that allow
us to "fine tune" your battery selection to match your autonomy
requirements so that you do not pay for more battery than you need.
Expertise in battery chemistry, technology & fabrication combine to provide
you a dc power solution with 10, 20 & 25 year warranties. Our unique
perspective has given us the opportunity to produce remarkable
innovations in battery design, assembly & accessories. Small rechargeable
secondary power batteries are also available for your OEM application
Stationary & Motive Batteries

18. 18
Battery Life Considerations in Energy Storage Applications
and
Their Effect on Life Cycle Costing
Jim McDowaIl- SaftAmerica
IEEE
Introduction - Life Cycle Costing
The term ‘energy storage’ encompasses a group of emerging
applications that will soon become prominent in
supporting the delivery of electrical power to the end user. As the
power engineering community becomes more aware of energy
storage systems, the benefits of such systems have to be
balanced against their cost. That cost has to be justified against
the alternatives, which could include, for example: doing nothing
and living with power quality problems; increased use of peaking
generators; or building a new transmission line. The normal rule
for making these cost justifications is a life cycle costing (LCC)
analysis, in which all costs associated with the alternative
approaches are defined over a certain time period, often 10 or 20
years. These costs are discounted to a net present value, so that
they can be directly compared. The LCC approach is important,

19. 19
because energy stc}rage systems often have higher initial costs
than their alternatives, and this is the best way to judge whether
this represents a sound investment.
In the same way, an LCC analysis can be used to differentiate
between competing energy storage technologies. This
is particularly the case for new technologies, which typically have
a high cost when first introduced. Each technology will often have
a particular advantage, such as cycling capability, energy
efficiency, high performance, etc. Where that advantage
translates to a critical benefit for a particular application, LCC may
justi& using the new product, even at its steep ‘introductory’ price.
As the production volume picks up and the price comes down, the
analysis will allow use of the product to be justified for an
increasingly broad sector of the market.
Application Requirements
As a whole, energy storage applications place certain
characteristic requirements on the energy storage device.
Three of the most important characteristics are:
Long operating life
High power capability

20. 20
Good charge/discharge cycling capability
A particular application may require just one or two of these
characteristics, or it may require all of them. This presentation will
discuss how these requirements relate to battery systems, and
how they can affect the LCC analysis.
For some battery types, there are design variants within the
overall technology that can give drastically different performance
against these requirements. For example, in lead-acid batteries,
thin plate designs give high power, but short life and poor cycling
capability, while tubular plate designs exhibit quite long life and
good cycling, but low power capability. These differences would
show up clearly in an LCC analysis.
Operating Life
Obviously, the longer a battery can operate without replacement,
the lower its life cycle cost will be. This does not mean, however,
that long life batteries have lower life cycle costs than shorter life
batteries. Because of the discounting method used to establish
the net present value (NPV) of a future expense, the NPV of
battery replacement in, say, year 10 may be less than half the
cost in the first year. If a 10-year battery costs half as much
initially as a 20-year battery, this simple analysis would show the
10-year battery as a better investment. However, a true LCC

21. 21
analysis will take other factors into account, such as the cost of
individual cell replacements or other increased maintenance as
the battery nears the end of life. There are other costs associated
with battery replacement, such as the cost of decommissioning
and disposing of the old battery, and possible downtime/lost
revenue costs during the replacement process. All these costs
should be considered in the LCC analysis, and this can have a big
effect on the end result.
Another big factor in operating life is the operating temperature.
The aging process in battery systems is generally in the form of
chemical reactions, which speed up at higher temperatures. In the
lead-acid system, for example, the life is cut by 50”A for each
10°C increase in operating temperature. Other systems are less
affected by temperature: the life of nickel-cadmium batteries, for
example, is cut by just 20’ZO for the same 10 degree C increase.
These numbers maybe simply inserted into the LCC analysis, or
the picture may become more complex. For example, a
comparison could be made between nickel-cadmium batteries
operating at normal ambient temperature, and lead-acid in an air
conditioned environment. In the latter case, the LCC would have
to include the ongoing energy costs for running the AIC, plus the
associated maintenance and component replacement costs.
High Power Capability

22. 22
High power is needed in several energy storage applications,
ranging in size from small residential fuel cell generators to large
systems for providing spinning reserve. High power capability
requires, among other things, a large plate surface area. In most
technologies, this translates to the use of more and thinner plates,
and in lead-acid batteries, this also results in shorter lives. In
Figure 1 (not shown) the relationship of life against high power
performance for
lead-acid and Ni-Cd batteries can be seen. In this case, ‘capacity
utilization’ is the percentage of the rated 8-hour capacity that can
be removed in a typical 20-minute discharge. For lead-acid
batteries, it is clear that high power capability comes at the
expense of battery life.
Charge-Discharge Cycling
Good cycling capability is an obvious requirement in those
systems where the battery will be routinely discharged,
sometimes many times per day. It is in this area that many new
battery technologies, such as flow batteries and lithium ion, are
showing large advantages. For most technologies, the cycle life
increases exponentially as the depth of discharge decreases.
Figure 2 shows typical cycling capability for conventional battery
types, based on 80°A depth of discharge. The actual cycle life is

23. 23
heavily dependent on plate design and active material
composition for all the types covered. For example, the figure of
800 cycles shown for vented lead-acid is based on pasted plates
using an antimony-based alloy grid. Tubular cells with the same
alloy would give about 1200 cycles, while cells with pasted lead-
calcium grids would typically only give about 100 cycles. Nickel-
cadmium, based on the sintered/plastic bonded hybrid design,
has a clear advantage among today’s battery technologies.
0-7803-7031-7/01/$10.00 (C) 2001 IEEE
0-7803-7173-9/01/$10.00 © 2001 IEEE 453
Ven
o 500 1000 1500 2000 2500 3000 3500
Cycle life (80% DoD)
Flow batteries represent a new class of batteries, in which the
active materials, in the form of liquids, are pumped through
electrode stacks, where the cell reaction takes place. Very little
has been published on the wear-out mechanisms for these
batteries, but their cycle life is expected to greatly exceed that of
conventional batteries.
Unfortunately for the end user, battery life is not the specified float
service life plus the number of cycles shown above. The actual

24. 24
life is a compromise between the two, so the expected cycling
conditions must be accurately known in order for a realistic LCC
analysis to be performed.
Case Study - the PREPA BESS
The Puerto Rico Electric Power Authority (PREPA) installed a
battery energy storage system (BESS) in 1994, primarily to
provide a spinning reserve function. The system was the basis of
an LCC analysis performed on contract for Sandia National
Laboratories and published at a later date’. The battery was a
modified UPS (thin plate) vented lead-acid design with lead-
calcium plate grids, and the LCC assumption was that it would be
replaced after 10 years.
In 1998, after just four years of operation, some parts of the cells
had been replaced, mostly in the battery strings on the upper floor
of the two-floor installation. The rate of cell failure continued to
escalate, and the battery system had to be decommissioned.
Sandia published a ‘lessons learned’ report in 19992.
Although these failures seemed to come as a surprise to those
involved with the project, they should have been expected. This
type of battery has a float service life of approximately 10 years at
25°C. When operated at around 35”C, as was quite normal for the
upper floor of the building, this life would be reduced to 5 years.

25. 25
The battery was also subjected to numerous shallow cycles for
frequency control operation, which reduced its life still further.
Four years of battery life should not have been a surprise to
anyone.
This installation was certainly not the disaster that it might seem
to have been. The frequency control operation yielded benefits
that had not been expected when the original studies were
performed. These benefits were therefore not included in the LCC
analysis. PREPA is re-powering the BESS with new batteries,
although now the battery area will be air-conditioned, and different
lead-acid batteries will be used, with better cycling capability. It is
to be hoped that all these factors have been taken into account in
a new LCC!
Conclusions
The life cycle costing approach is indispensable in justifying the
use of energy storage systems, and in choosing between
competing energy storage devices. To gain the proper benefit
from this tool requires a proper appraisal of the impact of
operating conditions on battery life, and a realistic appraisal of all
costs involved with system operation. Many energy storage
systems perform multiple functions, such as spinning reserve and
frequency control, and the LCC should take this fully into account.

26. 26
References
‘ Sandia Contractor Report SAND!XL1905, Battew Energy Skmge
Systems L&e Cycle Costs Case Studies
2 Sandia Report SAND99-2232, Lessons Learned from the
Puerto Rico Battery Energy Storage System
0-7803-7031-7/01/$10.00 (C) 2001 IEEE
0-7803-7173-9/01/$10.00 © 2001 IEEE 455