battery charger of a aircraft battery

45
1. INTRODUCTION The purpose of this chapter is to introduce and explain the basic theory and characteristics of batteries. The batteries which are discussed and illustrated have been selected as representative of many models and types which are used in the Navy today. No attempt has been made to cover every type of battery in use, however, after completing this chapter you will have a good working knowledge of the batteries which are in general use. First, you will learn about the building block of all batteries, the CELL. The explanation will explore the physical makeup of the cell and the methods used to combine cells to provide useful voltage, current, and power. The chemistry of the cell and how chemical action is used to convert chemical energy to electrical energy are also discussed. Batteries are widely used as sources of direct-current electrical energy in automobiles, boats, aircraft, ships, portable electric/electronic equipment, and lighting equipment. In some instances, they are used as the only source of power; while in others, they are used as a secondary or standby power source. A battery consists of a number of cells assembled in a common container and connected together to function as a source of electrical power.

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Page 1: BATTERY CHARGER OF A AIRCRAFT BATTERY

1. INTRODUCTION

The purpose of this chapter is to introduce and explain the basic theory and

characteristics of batteries. The batteries which are discussed and illustrated have been selected

as representative of many models and types which are used in the Navy today. No attempt has

been made to cover every type of battery in use, however, after completing this chapter you will

have a good working knowledge of the batteries which are in general use.

First, you will learn about the building block of all batteries, the CELL. The explanation

will explore the physical makeup of the cell and the methods used to combine cells to provide

useful voltage, current, and power. The chemistry of the cell and how chemical action is used to

convert chemical energy to electrical energy are also discussed.

Batteries are widely used as sources of direct-current electrical energy in automobiles,

boats, aircraft, ships, portable electric/electronic equipment, and lighting equipment. In some

instances, they are used as the only source of power; while in others, they are used as a

secondary or standby power source. A battery consists of a number of cells assembled in a

common container and connected together to function as a source of electrical power.

1.1 THE CELL

A cell is a device that transforms chemical energy into electrical energy. The simplest

cell, known as either a galvanic or voltaic cell is shown in figure 2-1. It consists of a piece of

carbon (C) and a piece of zinc (Zn) suspended in a jar that contains a solution of water (H20) and

sulfuric acid (H2S0 4) called the electrolyte.

The cell is the fundamental unit of the battery. A simple cell consists of two electrodes

placed in a container that holds the electrolyte. In some cells the container acts as one of the

electrodes and, in this case, is acted upon by the electrolyte. This will be covered in more detail

later.

Page 2: BATTERY CHARGER OF A AIRCRAFT BATTERY

Figure 2-1.—Simple voltaic or galvanic cell.

1.2 ELECTRODES

The electrodes are the conductors by which the current leaves or returns to the

electrolyte. In the simple cell, they are carbon and zinc strips that are placed in the electrolyte;

while in the dry cell (fig.2-2), they are the carbon rod in the center and zinc container in which

the cell is assembled.

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Figure 2-2—Dry cell, cross-sectional view

ELECTROLYTE

The electrolyte is the solution that acts upon the electrodes. The electrolyte, which

provides a path for electron flow, may be a salt, an acid, or an alkaline solution. In the simple

galvanic cell, the electrolyte is in a liquid form. In the dry cell, the electrolyte is a paste.

CONTAINER

The container which may be constructed of one of many different materials provides a

means of holding (containing) the electrolyte. The container is also used to mount the electrodes.

In the voltaic cell the container must be constructed of a material that will not be acted upon by

the electrolyte.

PRIMARY CELL

A primary cell is one in which the chemical action eats away one of the electrodes,

usually the negative electrode. When this happens, the electrode must be replaced or the cell

must be discarded. In the galvanic-type cell, the zinc electrode and the liquid electrolyte are

usually replaced when this happens. In the case of the dry cell, it is usually cheaper to buy a new

cell.

SECONDARY CELL

A secondary cell is one in which the electrodes and the electrolyte are altered by the

chemical action that takes place when the cell delivers current. These cells may be restored to

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their original condition by forcing an electric current through them in the direction opposite to

that of discharge. The automobile storage battery is a common example of the secondary cell.

ELECTROCHEMICAL ACTION

If a load (a device that consumes electrical power) is connected externally to the

electrodes of a cell, electrons will flow under the influence of a difference in potential across the

electrodes from the CATHODE (negative electrode), through the external conductor to the

ANODE (positive electrode). A cell is a device in which chemical energy is converted to

electrical energy. This process is called ELECTROCHEMICAL action. The voltage across the

electrodes depends upon the materials from which the electrodes are made and the composition

of the electrolyte. The current that a cell delivers depends upon the resistance of the entire

circuit, including that of the cell itself. The internal resistance of the cell depends upon the size

of the electrodes, the distance between them in the electrolyte, and the resistance of the

electrolyte. The larger the electrodes and the closer together they are in the electrolyte (without

touching), the lower the internal resistance of the cell and the more current the cell is capable of

supplying to the load.

Nickel-Cadmium Cell

The nickel-cadmium cell (NICAD) is far superior to the lead-acid cell. In comparison to

lead- the adding of electrolyte or water. The major difference between the nickel-cadmium cell

and the lead-acid cell is the material used in the cathode, anode, and electrolyte. In the nickel-

cadmium cell the cathode is cadmium hydroxide, the anode is nickel hydroxide, and the

electrolyte is potassium hydroxide and water. The nickel-cadmium and lead-acid cells have

capacities that are comparable at normal discharge rates, but at high discharge rates the nickel-

cadmium cell can deliver a larger amount of power. In addition the nickel-cadmium cell can:

1. Be charged in a shorter time,

2. Stay idle longer in any state of charge and keep a full charge when stored for a longer period

of time, and

3. Be charged and discharged any number of times without any appreciable damage.

Due to their superior capabilities, nickel-cadmium cells are being used extensively in

many military applications that require a cell with a high discharge rate. A good example is in

the aircraft storage battery.

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Silver-Zinc Cells

The silver-zinc cell is used extensively to power emergency equipment. This type of cell

is relatively expensive and can be charged and discharged fewer times than other types of cells.

When compared to the lead-acid or nickel-cadmium cells, these disadvantages are overweighed

by the light weight, small size, and good electrical capacity of the silver-zinc cell.

The silver-zinc cell uses the same electrolyte as the nickel-cadmium cell (potassium

hydroxide and water), but the anode and cathode differ from the nickel-cadmium cell. The anode

is composed of silver oxide and the cathode is made of zinc.

Silver-Cadmium Cell

The silver-cadmium cell is a fairly recent development for use in storage batteries. The

silver-cadmium cell combines some of the better features of the nickel-cadmium and silver-zinc

cells. It has more than twice the shelf life of the silver-zinc cell and can be recharged many more

times. The disadvantages of the silver-cadmium cell are high cost and low voltage production.

The electrolyte of the silver-cadmium cell is potassium hydroxide and water as in the nickel-

Cadmium and silver-zinc cells. The anode is silver oxide as in the silver-zinc cell and the

cathode is cadmium hydroxide as in the NiCad cell. You may notice that different combinations

of materials are used to form the electrolyte, cathode, and anode of different cells. These

combinations provide the cells with different qualities for many varied applications.

2. NICKEL-CADMIUM BATTERY

The nickel–cadmium battery (NiCad battery or NiCad battery) is a type of rechargeable

battery using nickel oxide hydroxide and metallic cadmium as electrodes. The abbreviation Ni-

Cd is derived from the chemical symbols of nickel (Ni) and cadmium (Cd): the abbreviation

NiCad is a registered trademark of SAFT Corporation, although this brand name is commonly

used to describe all Ni–Cd batteries.

Wet-cell nickel-cadmium batteries were invented in 1899. A Ni-Cd battery has a terminal

voltage during discharge of around 1.2 volts which decreases little until nearly the end

ofdischarge. Ni-Cd batteries are made in a wide range of sizes and capacities, from portable

sealed types interchangeable with carbon-zinc dry cells, to large ventilated cells used for standby

powerand motive power. Compared with other types of rechargeable cells they offer good cycle

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life and capacity, good performance at low temperatures, and work well at high discharge rates

(using the cell capacity in one hour or less). However, the materials are more costly than types

such as the lead acid battery, and the cells have higher self-discharge rates than some othertypes.

Sealed Ni-Cd batteries require no maintenance.

Sealed Ni-Cd cells were at one time widely used in portable power tools, photography

equipment, flashlights, emergency lighting, and portable electronic devices. The superior

capacity of the Nickel-metal hydride batteries, and more recently their lower cost, has largely

supplanted their use. Further, the environmental impact of the disposal of the heavy metal

cadmium has contributed considerably to the reduction in their use. Within the European Union,

they can now only be supplied for replacement purposes although they can be supplied for

certain specified types of new equipment such as medical devices.

Nickel–cadmium battery

From top to bottom: "Gumstick", AA, and AAA Ni–Cd

batteries

2.1 CHARACTERISTICS

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The maximum discharge rate for a Ni–Cd battery varies by size. For a common AA-size

cell, the maximum discharge rate is approximately 18 amps; for a D size battery the discharge

rate can be as high as 35 amps.

Model-aircraft or -boat builders often take much larger currents of up to a hundred amps or

so from specially constructed Ni–Cd batteries, which are used to drive main motors. 5–6 minutes

of model operation is easily achievable from quite small batteries, so a reasonably high power-

to-weight figure is achieved, comparable to internal combustion motors, though of lesser

duration. In this, however, they have been largely superseded by lithium polymer (Lipo) and

lithium iron phosphate (Life) batteries, which can provide even higher energy densities.

Voltage

Ni–Cd cells have a nominal cell potential of 1.2 volts (V). This is lower than the 1.5 V of

alkaline and zinc–carbon primary cells, and consequently they are not appropriate as a

replacement in all applications. However, the 1.5 V of a primary alkaline cell refers to its initial,

rather than average, voltage. Unlike alkaline and zinc–carbon primary cells, a Ni–Cd cell's

terminal voltage only changes a little as it discharges. Because many electronic devices are

designed to work with primary cells that may discharge to as low as 0.90 to 1.0 V per cell, the

relatively steady 1.2 V of a Ni–Cd cell is enough to allow operation. Some would consider the

near-constant voltage a drawback as it makes it difficult to detect when the battery charge is low.

Ni–Cd batteries used to replace 9 V batteries usually only have six cells, for a terminal

voltage of 7.2 volts. While most pocket radios will operate satisfactorily at this voltage, some

manufacturers such as Varta made 8.4 volt batteries with seven cells for more critical

applications.

12 V Ni–Cd batteries are made up of 10 cells connected in series.

Charging

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Ni–Cd batteries can be charged at several different rates, depending on how the cell was

manufactured. The charge rate is measured based on the percentage of the amp-hour capacity the

battery is fed as a steady current over the duration of the charge. Regardless of the charge speed,

more energy must be supplied to the battery than its actual capacity, to account for energy loss

during charging, with faster charges being more efficient. For example, an "overnight" charge,

might consist of supplying a current equals to one tenth the amperehourrating (C/10) for 14–16

hours; that is, a 100 mAh battery takes 10mA for 14 hours, for a total of 140 mAh to charge at

this rate. At the rapid-charge rate, done at 100% of the rated capacity of the battery in 1 hour

(1C), the battery holds roughly 80% of the charge, so a 100 mAh battery takes 120 mAh to

charge (that is, approximately 1 hour and fifteen minutes). Some specialized batteries can be

charged in as little as 10–15 minutes at a 4C or 6C charge rate, but this is very uncommon. It also

exponentially increases the risk of the cells overheating and venting due to an internal

overpressure condition: the cell's rate of temperature rise is governed by its internal resistance

and the square of the charging rate. At a 4C rate, the amount of heat generated in the cell is

sixteen times higher than the heat at the 1C rate. The downside to faster charging is the higher

risk of overcharging, which can damage the battery.[3] And the increased temperatures the cell

has to endure (which potentially shortens its life).

The safe temperature range when in use is between −20°C and 45°C. During charging,

the battery temperature typically stays low, around 0°C (the charging reaction absorbs heat), but

as the battery nears full charge the temperature will rise to 45–50°C. Some battery chargers

detect this temperature increase to cut off charging and prevent over-charging.

When not under load or charge, a Ni–Cd battery will self-discharge approximately 10% per

month at 20°C, ranging up to 20% per month at higher temperatures. It is possible to perform a

trickle charge at current levels just high enough to offset this discharge rate; to keep a battery

fully charged. However, if the battery is going to be stored unused for a long period of time, it

should be discharged down to at most 40% of capacity (some manufacturers recommend fully

discharging and even short-circuiting once fully discharged[citation needed]), and stored in a cool, dry

environment.

Charging method

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A Ni–Cd battery requires a charger with a slightly different voltage than for a lead–acid

battery, especially if the battery has 11 or 12 cells. Also a charge termination method is needed if

a fast charger is used. Often battery packs have a thermal cut-off inside that feeds back to the

charger telling it to stop the charging once the battery has heated up and/or a voltage peaking

sensing circuit. At room temperature during normal charge conditions the cell voltage increases

from an initial 1.2 V to an end-point of about 1.45 V. The rate of rise increases markedly as the

cell approaches full charge. The end-point voltage decreases slightly with increasing

temperature.

Overcharging

Sealed Ni–Cd cells consist of a pressure vessel that is supposed to contain any generation

of oxygen and hydrogen gases until they can recombine back to water. Such generation typically

occurs during rapid charge and discharge and exceedingly at overcharge condition. If the

pressure exceeds the limit of the safety valve, water in the form of gas is lost. Since the vessel is

designed to contain an exact amount of electrolyte this loss will rapidly affect the capacity of the

cell and its ability to receive and deliver current. To detect all conditions of overcharge demands

great sophistication from the charging circuit and a cheap charger will eventually damage even

the best quality cells.

Is not significantly affected by very high discharge currents. Even with discharge rates as

high as 50C; a Ni–Cd battery will provide very nearly its rated capacity. By contrast, a

lead acid battery will only provide approximately half its rated capacity when discharged

at a relatively modest 1.5C.

Nickel–metal hydride (NiMH) batteries are the newest, and most similar, competitor to Ni–

Cd batteries.

2.2Applications

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Sealed Ni–Cd cells may be used individually, or assembled into battery packs containing

two or more cells. Small cells are used for portable electronics and toys, often using cells

manufactured in the same sizes as primary cells. When Ni–Cd batteries are substituted for

primary cells, the lower terminal voltage and smaller ampere-hour capacity may reduce

performance as compared to primary cells. Miniature button cells are sometimes used in

photographic equipment, hand-held lamps (flashlight or torch), computer-memory standby, toys,

and novelties.

Specialty Ni–Cd batteries are used in cordless and wireless telephones, emergency

lighting, and other applications. With a relatively low internal resistance, they can supply high

surge currents. This makes them a favorable choice for remote-controlled electric model

airplanes, boats, and cars, as well as cordless power tools and camera flash units.

Larger flooded cells are used for aircraft starting batteries, electric vehicles, and standby power.

2.3Availability

Ni–Cd cells are available in the same sizes as alkaline batteries, from AAA through D, as

well as several multi-cell sizes, including the equivalent of a 9 volt battery. A fully charged

single Ni–Cd cell, under no load, carries a potential difference of between 1.25 and 1.35 volts,

which stays relatively constant as the battery is discharged. Since an alkaline battery near fully

discharged may see its voltage drop to as low as 0.9 volts, Ni–Cd cells and alkaline cells are

typically interchangeable for most applications.

In addition to single cells, batteries exist that contain up to 300 cells (nominally 360

volts, actual voltage under no load between 380 and 420 volts). This many cells are mostly used

in automotive and heavy-duty industrial applications. For portable applications, the number of

cells is normally below 18 cells (24V). Industrial-sized flooded batteries are available with

capacities ranging from 12.5Ah up to several hundred Ah.

Comparison with other batteries

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Recently, nickel–metal hydride and lithium-ion batteries have become commercially

available and cheaper, the former type now rivaling Ni–Cd batteries in cost. Where energy

density is important, Ni–Cd batteries are now at a disadvantage compared with nickel–metal

hydride and lithium-ion batteries. However, the Ni–Cd battery is still very useful in applications

requiring very high discharge rates because it can endure such discharge with no damage or loss

of capacity.

When compared to other forms of rechargeable battery, the Ni–Cd battery has a number of

distinct advantages:

The batteries are more difficult to damage than other batteries, tolerating deep discharge

for long periods. In fact, Ni–Cd batteries in long-term storage are typically stored fully

discharged. This is in contrast, for example, to lithium ion batteries, which are less stable

and will be permanently damaged if discharged below a minimum voltage.

Ni–Cd batteries typically last longer, in terms of number of charge/discharge cycles, than

other rechargeable batteries such as lead/acid batteries.

Compared to lead–acid batteries, Ni–Cd batteries have a much higher energy density. A

Ni–Cd battery is smaller and lighter than a comparable lead–acid battery. In cases where

size and weight are important considerations (for example, aircraft), Ni–Cd batteries are

preferred over the cheaper lead–acid batteries.

In consumer applications, Ni–Cd batteries compete directly with alkaline batteries. A Ni–

Cd cell has a lower capacity than that of an equivalent alkaline cell, and costs more.

However, since the alkaline batteries chemical reaction is not reversible, a reusable Ni–

Cd battery has a significantly longer total lifetime. There have been attempts to create

rechargeable alkaline batteries, or specialized battery chargers for charging single-use

alkaline batteries, but none that have seen wide usage.

The terminal voltage of a Ni–Cd battery declines more slowly as it is discharged,

compared with carbon–zinc batteries. Since alkaline batteries voltage drops significantly

as the charge drops, most consumer applications are well equipped to deal with the

slightly lower Ni–Cd cell voltage with no noticeable loss of performance.

The capacity of a Ni–Cd battery Compared to Ni–Cd batteries, NiMH batteries have a

higher capacity and are less toxic, and are now more cost effective. However, a Ni–Cd

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battery has a lower self-discharge rate (for example, 20% per month for a Ni–Cd battery,

versus 30% per month for a traditional NiMH under identical conditions), although low

self-discharge NiMH batteries are now available, which have substantially lower self-

discharge than either Ni–Cd or traditional NiMH batteries. This results in a preference for

Ni–Cd over NiMH batteries in applications where the current draw on the battery is lower

than the battery's own self-discharge rate (for example, television remote controls). In

both types of cell, the self-discharge rate is highest for a full charge state and drops off

somewhat for lower charge states. Finally, a similarly sized Ni–Cd battery has a slightly

lower internal resistance, and thus can achieve a higher maximum discharge rate (which

can be important for applications such as power tools).

The primary trade-off with Ni–Cd batteries is their higher cost and the use of

cadmium. This heavy metal is an environmental hazard, and is highly toxic to all higher forms of

life. They are also more costly than lead–acid batteries because nickel and cadmium cost more.

One of the biggest disadvantages is that the battery exhibits a very marked negative temperature

coefficient. This means that as the cell temperature rises, the internal resistance falls. This can

pose considerable charging problems, particularly with the relatively simple charging systems

employed for lead–acid type batteries. Whilst lead–acid batteries can be charged by simply

connecting a dynamo to them, with a simple electromagnetic cut-out system for when the

dynamo is stationary or an over-current occurs, the Ni–Cd battery under a similar charging

scheme would exhibit thermal runaway, where the charging current would continue to rise until

the over-current cut-out operated or the battery destroyed itself. This is the principal factor that

prevents its use as engine-starting batteries. Today with alternator-based charging systems with

solid-state regulators, the construction of a suitable charging system would be relatively simple,

but the car manufacturers are reluctant to abandon tried-and-tested technology.

3. ELECTRONIC DEVICES

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3.1 NPN TRANSISTOR

NPN is one of the two types of bipolar transistors, consisting of a layer of P-

doped semiconductor (the "base") between two N-doped layers. A small current entering the

base is amplified to produce a large collector and emitter current. That is, when there is a

positive potential difference measured from the emitter of an NPN transistor to its base (i.e.,

when the base is high relative to the emitter) as well as positive potential difference measured

from the base to the collector, the transistor becomes active. In this "on" state, current flows

between the collector and emitter of the transistor. Most of the current is carried by electrons

moving from emitter to collector as minority carriers in the P-type base region. To allow for

greater current and faster operation, most bipolar transistors used today are NPN

because electron mobility is higher than whole mobility.

A mnemonic device for the NPN transistor symbol is not pointing in, based on the arrows

in the symbol and the letters in the name.[5

The symbol of an NPN BJT. The symbol is "notpointing in."

LIMITING VALUES In accordance with the Absolute Maximum Rating System (IEC 134).

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SYMBOL

PARAMETER CONDITIONS MIN. MAX UNIT

VCBOcollector-base voltageBC546

BC547

open emitter _

_

80

50

V

V

VCEOcollector-emitter voltageBC546

BC547

open base _

_

65

45

V

V

VEBOemitter-base voltageBC546

BC547

open collector _

_

6

6

V

V

IC collector current

(DC)

_ 100 mA

ICM peak collector

current

_ 200 mA

IBM peak base current _ 200 mA

Ptottotal power dissipation

Tamb 25 C; note 1

_ 500 mW

Tstg storage temperature -65 +150 C

Tj junction temperature _ 150 C

Tamb operating ambient

temperature

-65 +150 C

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Note

1. Transistor mounted on an FR4 printed-circuit board.

CHARACTERISTICSTj = 25 C unless otherwise specified.

SYMBOL PARAMETER CONDITIONS MIN. TYP MAX UNIT

ICBO collector cut-off

current

IE = 0; VCB= 30 V

IE = 0; VCB = 30 V;

Tj = 150 C

_

_

_

_

15

5

nA

A

IEBO emitter cut-off

current

IC = 0; VEB = 5 V _ _ 100 nA

hFEDC current gainBC546ABC546B; BC547B

BC547C

IC = 10 A; VCE = 5 V; see Figs 2, 3 and 4

90

150

270

_

_

_

_

_

_

DC current gain IBC546ABC546B; BC547BBC547CBC547

BC546

IC = 2 mA; VCE = 5 V;

see Figs 2, 3 and 4

110

200

420

110

110

180

290

520

_

220

450

800

800

450

_

_

_

_

VCEsatcollector-emitter saturation

voltage

IC = 10 mA; IB = 0.5

Ma

IC = 10 mA; IB = 0.5

mA

_

_

90

200

250

600

mV

mV

VBEsat base-emitter

saturation voltage

IC = 10 mA; IB = 0.5 mA; note 1

IC = 100 mA; IB = 5

_ 700 _ mV

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mA; note 1 _ 900 _ mV

VBE base-emitter

voltage

IC = 2 mA; VCE = 5

V; note 2

IC = 10 mA; VCE = 5

V

580

_

660

_

700

770

mV

mV

Cc collector

capacitance

IE = ie = 0; VCB = 10

V; f = 1 MHz

_ 1.5 _ pF

Ce emitter capacitance IC = ic = 0; VEB = 0.5

V; f = 1 MHz

_ 11 _ pF

fT transition frequency IC = 10mA; VCE = 5

V; f = 100 MHz

100 _ _ MHz

F noise figureIC = 200 A; VCE = 5 V;

RS = 2 k; f = 1 kHz;

B = 200 Hz

_ 2 10 dB

Notes

1. VBE sat decreases by about 1.7 mV/K with increasing temperature.

2. VBE decreases by about 2 mV/K with increasing temperature.

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Fig.2 DC Current gain; typical values.

handbook, full pagewidth

0

250

50

100

150

200

MBH723

10−2 10−1

hFE

1 IC (mA) 1010 3 102

VCE = 5 V

BC546A.

NPN general purpose transistors BC546; BC547

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Fig.3 DC Current gain; typical values.

handbook, full pagewidth

0

300

100

200

MBH724

10−2 10−1

hFE

1 IC (mA)10 103 102

VCE = 5 V

BC546B; BC547B.

Philips Semiconductors Product specification

NPN general purpose transistors BC546; BC547

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Fig.4 DC Current gain; typical values.

handbook, full pagewidth

0

600

200

400

MBH725

10−2 10−1

hFE

1 IC (mA)10 103 102

VCE = 5 V

BC547C.

Philips Semiconductors Product specification

NPN general purpose transistors

PACKAGE OUTLINE

BC546; BC547

3.2 ZENER DIODE

A Zener diode is a diode which allows current to flow in the forward direction in the same

manner as an ideal diode, but will also permit it to flow in the reverse direction when the voltage

is above a certain value known as the breakdown voltage, "zener knee voltage" or "zener

voltage" or "avalanche point".

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The device was named after Clarence Zener, who discovered this electrical property.

Many diodes described as "zener" diodes rely instead on avalanche breakdown as the

mechanism. Both types are used. Common applications include providing a reference voltage

for voltage regulators, or to protect other semiconductor devices from momentary voltage pulses

Zener diode

Zener diode

Type Passive

Working principle Zener breakdown

First production Clarence Zener (1934)

Electronic symbol

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3.2.1FEATURES

1 . Low forward voltage

2 .High current capability

3 .Low leakage current

4 .High surge capability

5 .Low cost

3.2.2MECHANICAL DATA

Case: Molded plastic use UL 94V-0 recognized Flame retardant epoxy

Terminals: Axial leads, solder able per MIL-STD-202, method 208

Polarity: Color band denotes cathode

Mounting Position: Any

3.3 OPERATIONAL AMPLIFIER

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An operational amplifier is a high-gain direct-coupled amplifier that is normally used in

feedback connections. If the amplifier characteristics are satisfactory, the transfer function of the

amplifier with feedback can often be controlled primarily by the stable and well-known values of

passive feedback elements.

The term operational amplifier evolved from original applications in analog computation

where these circuits were used to perform various mathematical operations such as summation

and integration. Because of the performance and economic advantages of available units, present

applications extend far beyond the original ones, and modern operational amplifiers are used as

general purpose analog data-processing elements.

High-quality operational amplifiers1were available in the early 1950s. These amplifiers were

generally committed to use with analog computers and were not used with the flexibility of

modern units.

LM124/LM224/LM324/LM2902

Low Power Quad Operational Amplifiers

4.1General Description

The LM124 series consists of four independent, high gain internally frequency compensated

operational amplifiers which were designed specifically to operate from a single power supply

over a wide range of voltages. Operation from split power supplies is also possible and the low

power supply current drain is independent of the magnitude of the power supply voltage.

Application areas include transducer amplifiers, DC gain blocks and all the conventional op amp

circuits which now can be more easily implemented in single power supply systems. For

example, the LM124 series can be directly operated off of the standard +5V power supply

voltage which is used in digital systems and will easily provide the required interface electronics

without requiring the additional ±15V power supplies

1

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.2Advantages

Eliminates need for dual supplies

Four internally compensated op amps in a single package

Allows directly sensing near GND and VOUT also goes to GND

Compatible with all forms of logic

Power drain suitable for battery operation

4.3Features

Internally frequency compensated for unity gain

Large DC voltage gain 100 dB

Wide bandwidth (unity gain) 1 MHz(temperature compensated)

Wide power supply range:

Single supply 3V to 32V

or dual supplies ±1.5V to ±16V

Very low supply current drain (700 μA)—essentially

Independent of supply voltage

Low input biasing current 45 nA (temperature compensated)

Low input offset voltage 2 mV and offset current: 5 nA

Input common-mode voltage range includes ground

Differential input voltage range equal to the power supply voltage

Large output voltage swing 0V to V+ − 1.5V

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00929934 00929935

Supply Current Voltage Gain

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Input Voltage Range Input Current

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4. BATTERY CHARGER

RF80-M® Aircraft Battery Charger/Analyzer

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cv `

The NEW CHRISTIE® RF80-M® Aircraft Battery Charger/Analyzer is the latest

evolution of the popular RF80 series which has been the worldwide industry standard for

decades. The RF80-M is the first product of its kind to feature an advanced microcontroller with

touch-screen display. The optional ABMS-10X PC Interface provides PC control, data-logging,

diagnostics and expanded battery processing capabilities

Features:

7 Inch Touch Screen Display

Optional PC Interface

Up to 80 amps ReFLEX® Charge, 60 amps CC/CP Charge and 60 amps Discharge

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Manual Mode

Program Mode

Constant Current, Constant Potential and ReFLEX® charge modes

Alarm signals at each end of task

Programmable Alert

Proven RF80-K Power Section

Enhanced safety features

Benefits:

Intuitive, easy to use, and large bright display of volts, amps and time

Compatible with ABMS-10X Battery Management Sys-tem for PC control, individual cell monitoring, temp sensing, data-logging, diagnostics and expanded bat-tery processing capabilities

Fully compatible with all battery manufacturer’s

component maintenance manuals

Allows single or multiple charge/discharge tasks to be run in sequence

Battery parameters may be stored and custom task sequences saved for automatic processing

The only charger/analyzer offering all 3 charge modes including ReFLEX for fast charging.

5. Circuit operation:

The batteries used for aircraft starting are Nickel cadmium alkaline batteries. The main

advantage of Ni-Cd batteries is that it can be used for very high current discharge for short

duration. Therefore where ever storage of total energy is less critical than high discharge rate,

such as aircraft starting, these batteries are preferred.

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The charging circuit must have two modes of charging, namely high current charging

called boost charge till the battery attains around 90 % charge, and a constant potential float

charging to maintain the battery in a charged condition by compensating for leakage.

1.45V

Voltage

1.2V

Time

Charging curve for Nicd cell

6. CONCLUSION

In the past few decades, Ni–Cd batteries have had internal resistance as low as alkaline

batteries. Today, all consumer Ni–Cd batteries use the "swiss roll" or "jelly-roll" configuration.

This design incorporates several layers of positive and negative material rolled into a cylindrical

shape. This design reduces internal resistance as there is a greater amount of electrode in contact

with the active material in each cell.

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Aircrafts usually utilize Nickel cadmium batteries for starting purpose once aircraft

generator can be made on and supplies the power thereafter. Nickel cadmium batteries are high

efficiency but costly batteries and need to be charged accurately.

7. DECLARATION

We here by declare that this project report entitled < BATTERY

CHARGER FOR AIRCRAFT BATTERY > has been prepared by us during

<date> to <date>, in partial fulfillment of the requirements for the award of

Bachelor of Technology in Electrical and Electronics Engineering.

We also declare that this work is a result our own effort and that it have not

been submitted to any other university for the award of any Degree/Diploma.

A.ALEKHYA (09RG1A0204)

M.SRILATHA (09RG1A0238)

S.ANUSHA (09RG1A0256)

Place: Suraram

Date:

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8. REFERENCES

1. http://www.christiecbs.com/RF80-M%20Brochure%20MAI%20%28A%29.pdf

2. S.U. Falk and A.J Salkind, Alkaline Storage Batteries, Wiley Press, New York, 1969.

3. David Linden, Handbook of Batteries (Second Edition), McGraw-Hill Inc., New York,

1994.

4. Hugh Morrow, “Cadmium,” Mining Annual Review – 2000, the Mining Journal Ltd.,

London, UK, August 2000.

5. M. Eskra, P. Ralston, M. Klein et al., “Nickel-Metal Hydride Replacement for VRLA

and Vented NiCd Aircraft Batteries,” IEEE Aerospace and Electronic Systems Society

Annual Battery Conference, Long Beach, CA, Jan 2001.

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