boatowners mechanical and electrical manual third edition pdf

Electrical Systems for Energy-Intensive Boats Additional Energy Sources Dual-Voltage DC Systems Fuel Cells, Higher-Voltage DC Boats, and Electric Propulsion CHAPTER 3.. However, Ihave ad

Trang 2

Third Edition

www.TechnicalBooksPDF.com

Trang 3

Boat’s Essential Systems

Trang 6

as permitted under the United States Copyright Act of 1976, no part

of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written permission of the publisher.

ISBN: 978-0-07-178406-1

MHID: 0-07-178406-3

The material in this eBook also appears in the print version of this title: ISBN: 978-0-07-143238-2, MHID: 0-07-143238-8.

eBook conversion by codeMantra

Version 2.0

All trademarks are trademarks of their respective owners Rather than put a trademark symbol after every occurrence of a trademarked

name, we use names in an editorial fashion only, and to the benefit of the trademark owner, with no intention of infringement of the

trademark Where such designations appear in this book, they have been printed with initial caps.

McGraw-Hill eBooks are available at special quantity discounts to use as premiums and sales promotions, or for use in corporate training programs To contact a representative please e-mail us at

Trang 7

TERMS OF USE

This is a copyrighted work and The McGraw-Hill Companies, Inc (“McGraw-Hill”) and its licensors reserve all rights in and to the

work Use of this work is subject to these terms Except as permitted under the Copyright Act of 1976 and the right to store and retrieve one copy of the work, you may not decompile, disassemble, reverse engineer, reproduce, modify, create derivative works based upon, transmit, distribute, disseminate, sell, publish or sublicense the work

or any part of it without McGraw-Hill’s prior consent You may use the work for your own noncommercial and personal use; any other use of the work is strictly prohibited Your right to use the work may

be terminated if you fail to comply with these terms.

THE WORK IS PROVIDED “AS IS.” McGRAW-HILL AND ITS LICENSORS MAKE NO GUARANTEES OR WARRANTIES AS

TO THE ACCURACY, ADEQUACY OR COMPLETENESS OF

OR RESULTS TO BE OBTAINED FROM USING THE WORK, INCLUDING ANY INFORMATION THAT CAN BE ACCESSED THROUGH THE WORK VIA HYPERLINK OR OTHERWISE, AND EXPRESSLY DISCLAIM ANY WARRANTY, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO IMPLIED

WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE McGraw-Hill and its licensors do not warrant or guarantee that the functions contained in the work will meet your requirements or that its operation will be uninterrupted or error free Neither McGraw-Hill nor its licensors shall be liable to you

or anyone else for any inaccuracy, error or omission, regardless of cause, in the work or for any damages resulting therefrom McGraw- Hill has no responsibility for the content of any information accessed through the work Under no circumstances shall McGraw-Hill and/or its licensors be liable for any indirect, incidental, special, punitive, consequential or similar damages that result from the use of or

Trang 8

inability to use the work, even if any of them has been advised of the possibility of such damages This limitation of liability shall apply to any claim or cause whatsoever whether such claim or cause arises in contract, tort or otherwise.

Trang 10

List of Troubleshooting Charts List of Tables

Preface and Acknowledgments to the Third Edition Preface and Acknowledgments to the Second Edition Introduction

CHAPTER 1 Establishing a Balanced Battery-Powered Electrical

System

Introduction Batteries Getting Down to Specifics Putting the Pieces Together Summary: A Balanced System

CHAPTER 2 Electrical Systems for Energy-Intensive Boats

Additional Energy Sources Dual-Voltage DC Systems Fuel Cells, Higher-Voltage DC Boats, and Electric Propulsion

CHAPTER 3

Maintaining and Troubleshooting a Battery-Powered Electrical System

Batteries

Trang 11

Alternators Voltage Regulators Diodes

CHAPTER 5 Corrosion, Bonding, Lightning Protection, and

Grounding

Corrosion Bonding and Cathodic Protection Lightning Protection

Grounding

CHAPTER 6 Battery Chargers, Inverters, Wind and Water

Generators, and Solar Panels

Battery Chargers Inverters

Wind and Water Generators

Trang 12

Electromagnetic and Radio Frequency Interference, and Saving Soaked Equipment

Marine Electronics Antennas and Radio Grounds Electromagnetic and Radio Frequency Interference Saving Soaked Equipment

CHAPTER 9 Diesel Engines: Operation and Maintenance,

Troubleshooting, and Winter Layup

Operation and Maintenance Troubleshooting Part 1: Failure to Start Troubleshooting Part 2: Operating Problems

Trang 13

CHAPTER 10 From Transmission to Propeller

Transmissions and Shaft Brakes Connecting a Transmission to a Propeller Shaft Shaft Seals

Struts, Bearings, and Propellers

CHAPTER 11 Refrigeration and Air-Conditioning

CFCs and the Ozone Hole Balancing Refrigeration Needs with Boat Use Air-Conditioning

Refrigeration and Air-Conditioning: Maintenance, Troubleshooting, and Repair

Charging and Topping-Off Procedures

CHAPTER 12 Tanks, Plumbing, Toilets, and Through-Hull Fittings

Tanks and Fittings Plumbing

Marine Toilets (Heads) Through-Hulls and Seacocks

Trang 14

Pumps Pump Switches Watermakers

CHAPTER 14 Steering Systems, Autopilots, and Wind Vanes

Steering Systems Autopilots

Wind Vane Self-Steering

CHAPTER 15 Stoves, Cabin Heaters, Gas-Powered Water Heaters,

and Lanterns

Gas Alcohol, Kerosene, and Diesel Appliances Carbon Monoxide Poisoning

CHAPTER 16 Blocks, Winches, Windlasses, and Bow Thrusters

Blocks Winches

Trang 15

Windlasses Bow Thrusters

CHAPTER 17 Spars, Standing Rigging, and Roller Reefing

Spars Standing Rigging Roller Reefing and Furling Glossary

Appendix A: Checklist of Winterizing Procedures Appendix B: Freeing Frozen Parts and Fasteners Appendix C: Tools and Spare Parts

Appendix D: Useful Tables Index

Trang 16

Chart 3-1 Battery/Alternator/Regulator Problems: Undercharging Chart 3-2 Battery/Alternator/Regulator Problems: Overcharging

Chart 3-3 Battery/Alternator/Regulator Problems: No Alternator Output

Trang 17

Chart 9-2 Diesel Engine Problems: Engine Cranks but Won’t Fire Chart 9-3 Overheating on Start-Up

Chart 9-4 Overheating in Operation

Chart 9-5 Smoke in Exhaust

Chart 10-1 Transmission Problems

Chart 11-1 Refrigeration and Air-Conditioning Problems: A Brief Overview

Chart 13-1 Flexible Impeller, Vane, and Rotary Pump Problems: No Flow

Chart 13-2 Centrifugal Pump Problems: No Flow or Reduced Flow Chart 14-1 Wheel Steering Failures: Rack-and-Pinion

Chart 14-2 Wheel Steering Failures: Cable and Pull-Pull

Chart 14-3 Wheel Steering Failures: Hydraulic

Chart 16-1 Electric Windlass: Failure to Operate

Trang 18

Table 1-1 Summary of Pros and Cons of Different Battery

Technologies

Cells and AGMs

Table 1-2 Life Cycles Versus Depth of Discharge for East Penn Gel-Table 1-3 Typical Power Consumption of Electrical Loads (12 Volts)

Table 1-4 Daily Power Requirements (12 Volts) of a Hypothetical Cruising Boat Anchored Off a Bahamian Beach

Table 1-5 Cycle Life of Trojan Industrial Batteries

Table 1-6 Typical KKK Alternator Outputs as a Function of Speed of Rotation and Temperature

Belts (approximately in belts)

Table 1-7 Horsepower Ratings for 3VX Super HC Molded Notch V- Belts (between ½ in and in.)

Table 1-8 Horsepower Ratings for 5VX Super HC Molded Notch V-Table 1-9 Horsepower Ratings for AX-Section Tri-Power Molded Notch V-Belts (½ in belts)

Table 1-10 Gassing Voltages for a 12-Volt Battery as a Function of Electrolyte Temperature

Table 1-11 Recommended Temperature-Compensated Charging and Float Voltages for East Penn Gel-Cells

Trang 19

Table 1-12 Recommended Temperature-Compensated Charging and Float Voltages for East Penn AGMs

Table 1-13 Designing Your Boat’s DC Electrical System

Table 3-1 Electrolyte Freezing Point as a Function of Battery State of Charge

Table 3-2 Electrolyte Specific Gravity as a Function of Temperature and Battery State of Charge

Table 3-3 Typical Specific Gravity Variations by Region

Table 3-4 Open-Circuit Voltage Versus State of Charge for East Penn Wet-Cell, Gel-Cell, and AGM Batteries

Table 4-1 Common Electric Cables Acceptable to the ABYC (U.S.) Table 4-2 ABYC DC Color Coding

Table 4-3 ABYC Color Codes for Engines and Accessory Wiring Table 4-4A Allowable Ampacity of Conductors (ABYC)

Table 4-4B Allowable Ampacity of Conductors (adapted from the ISO standard)

Table 4-5 Conductor Sizes for 10% Drop in Voltage (ABYC)

Table 4-6 Conductor Sizes for 3% Drop in Voltage (ABYC)

Table 4-7 Conversion of American Wire Sizes to European Standards Table 4-8 European-Style Volt Drop Table

Trang 20

Table 8-3 Representative Loss (Attenuation) in dB per 100 Feet of 50-Ohm Coaxial Cable

Table 8-4 Representative Loss (Attenuation) in dB per 100 Feet of 75-Ohm Coaxial Cable

Trang 21

Table 11-5 Danfoss BD50 Vital Statistics: Btu of Heat Removed per Watt-Hour of Energy Consumed

Trang 22

Table 13-3 Resistance of Various Common Fittings (expressed as feet

of pipe)

Table 13-4 Resistance per Foot of (Old) Pipe (expressed as feet of head) as a Function of Pipe Size and Water Flow Rate

Trang 24

Table D-12 Comparative Sheet Metal Thicknesses Table D-13 Equivalencies

Trang 25

Over time, the audience for this book has evolved The first edition was writtenfor hard-core cruising sailors It paid scant attention to such things as the

voluntary boatbuilding standards promulgated by the American Boat and YachtCouncil (ABYC) in the United States, and none whatsoever to the legally

enforceable standards then being developed by the International Standards

Organization (ISO) in Europe But then I found that in addition to cruisers, thebook was being used by a significant number of marine professionals—

surveyors, designers, and boatbuilders So, for the second edition I not onlyadded a considerable amount of new material, but I also “cleaned up” the bookfrom a standards-compliance perspective

Ten years later I find the book is now widely used by marine professionals allover the world At the same time, the ISO has substantially expanded the scope

of its standards Meanwhile, much of my original audience of cruising sailors hasbecome far better educated and sophisticated with respect to technical matters,and is capable of acting upon considerably more-complex information At theother end of the spectrum, a new generation of sailors, many with minimal

experience and limited technical knowledge, has taken up cruising Powerboaters

of all stripes have begun to use the book As a backdrop to these developments,the systems found on almost all boats have become increasingly sophisticated.These changes have created a major challenge in terms of defining the

audience for this third edition and in determining the level of detail and

complexity that should be included One thing, however, has not changed—theprimary objective of meeting the needs of cruising sailors, both those with

considerable experience as well as neophytes Within this general framework, Ihave also sought to meet the needs of industry professionals

In order to satisfy these somewhat divergent objectives, I have retained most

of the structure of the original book, because it has seemed to work so well overthe years and is already familiar to hundreds of thousands of readers However, Ihave added considerably more detail than in previous editions, and slotted innumerous new sections (e.g., a whole new chapter on boats with more-complexelectrical systems requirements, and new sections on lighting technologies, air-conditioning, watermakers, and bow thrusters) Overall, the book has expanded

by about 40%

Trang 26

In places, the level of detail will get a little overwhelming for the beginningreader (especially some of the electrical stuff), but I encourage perseverance; ifyour boat has the kinds of systems discussed in this book, you need to grapplewith the issues and subjects I cover For the professionals (and for the rest of us,because the world we live in becomes ever more legalistic), I have added manymore explicit references to ABYC and ISO standards Finally, given that all ofthis book, except for the sections dealing with spars, standing rigging, and sailreefing devices, is as applicable to most powerboats as it is to sailboats, I havemade some minor reorganization of the last chapters, relegating the few

specifically sailboat subjects to the last chapter

At the end of the day, the overall goal remains the same as ever, which is toprovide the reader, whoever he or she may be, with information that will enablethe systems on a boat to be designed, installed, and maintained in a manner thatwill minimize aggravation and maximize the enjoyment of boating

In addition to the literally hundreds of individuals and companies who haveaided me with earlier editions (see the Preface to the Second Edition), with thisedition I have once again received assistance from a large number of people Inparticular, I would like to thank: Ewen Thomson, Richard Cohen, Gregory Dash,and Abdel Mousa for their input on lightning; the folks at Xantrex (battery

chargers, inverters, and systems monitors), Bill Montgomery of Balmar

(alternators and DC generators), and Thane Lanz of Analytic Systems (DC-to-DC converters); Bill Owra (Everfair Enterprises) and Andy Kruse (SouthwestWindpower) for wind generator feedback; Craig Whitworth of the ElectricalApparatus Service Association; Mark Matousec and his successors at

Taylorbrite, Kinder Woodcock (Imtra), James Creveling (Nichia), and Ken

James (Deep Creek Enterprises) for their help on lighting, especially LEDs; BenLandis (Volvo) and Greg Eck (Yanmar); Kevin Woody (PYI), Michael Adler(VariProp), Chuck Angle (Flex-O-Fold), and Doug Rose (Volvo Penta) for input

on propellers, and Ken Nigel (Shaft Lok) on shaft locks; Rob Warren

(Frigoboat), Bengt Stenvinkel (Isotherm), and Kevin Alston (Glacier Bay) for agreat deal of technical input on refrigeration; Steve Rollins (Sea Recovery) andBill Edinger (Spectra) for help with watermakers; John Curry (Hydrovane) andHans Bernwall (Scanmar) for updating me on wind vanes; Steve Loutrel

(Navtec) for information on rod rigging; and Tony Jones (Lewmar) for feedback

on the sections on winches and windlasses

Trang 27

me access to many of the brightest and most energetic brains in the business,which has been of inestimable value

There are many others who have helped in both large and small ways Mythanks to all of you And then there is, as always, the crew at International

Marine, especially Molly Mulhern, Janet Robbins, and Margaret Cook—andillustrator Jim Sollers; it is always a pleasure to work with you

NIGEL CALDER

Maine, May 2005

Trang 28

In the six years since I wrote the first edition of this book there have been

significant changes in boat systems, particularly electrical systems, which would,

in themselves, have been justification for a second edition But in addition tothis, the success of the first edition has established me as a professional technicalwriter This has not only afforded me the luxury of studying the subjects covered

in this book full time, but has also brought me into contact with many of thesmartest and most innovative people in the boating equipment world, which hasgreatly improved my understanding of a number of complex issues As a result,for this second edition I felt it necessary to rewrite much of the first half of thebook, and significant sections of the second half The text has grown by at least20%, with numerous new illustrations, troubleshooting charts, and tables Theresult is a volume that I feel is, both in small ways and large, far superior to thefirst edition

In the course of writing this new edition, I have corresponded with, and

received help from, literally dozens of boat and equipment manufacturers andindividuals Some have devoted considerable amounts of time and resources toreviewing and correcting draft chapters; others have shown me their plant andequipment or helped in other ways I am especially indebted (in no particularorder) to Alan Fitzpatrick of Marine and General Battery, Rick Proctor of theCruising Equipment Company, David Smead of Ample Technology, Bob

Ajeman of Professional Mariner, Paul Michaelcyck of Ancor, Chuck Hawley atWest Marine, Jack Honey of Marine Technology, David Potter of Kemp Spars,Julian Whitlock of Whitlock Steering Systems, Gordan Lyall of Simpson

Lawrence, Michael Adler of Adler Barbour, Kevin Alston of Glacier Bay, JackDurrant of Ampair, Bill Owra of Everfair Enterprises, John Surrette of RollsBattery Co., Tom Hale and Lysle Gray at the American Boat and Yacht Council,Dick Troberg of Fluke, Wally Ivison of Norseman Marine, Don Kavenagh,

associate editor of Ocean Navigator magazine, Bob Loeser, Professors Geoffrey

Swain and Harry Lipsitt, experts in corrosion, and Ron Colby

The following companies have also provided information and support: ABI,ACDelco, Allcraft Corporation, Allison Marine Transmissions, American

Insulated Wire Corp., Ampair, Aqua-drive, Arco, Atlantic/Trident Solar

Products, Auto-Helm, Automate, Balmar, Barient, Barlow, Battery Council

Trang 29

International, Beckson Marine, Bertram Yacht, Blakes Lavac Taylors, Blue SeaSystems, BorgWarner Corporation, Brookes and Gatehouse, C H Corporation,Camper and Nicholson, Carol Cable Co., Caterpillar Tractor Co.,

Cetrek/Navstar, Climate Control Inc., CPT Inc., Danforth, Danfoss, Dart UnionCo., Delco Remy, Detroit Diesel, Dole Refrigerating Co., Don Allen Co., EdsonInternational, Force 10, Forespar, Four Seasons, Frigoboat, Frigomatic, Furuno,Furlex, Garrett Automotive Products Co., Givens Buoy, Gougeon Brothers,

Groco, Grunert Refrigeration, Guest, Halyard Marine Ltd., Hamilton Ferris,Harken, Hart Systems Inc., Heart Interface, Henderson Pumps, Holset

Engineering Co., Hood Yacht Systems, Hurth, Hydro-vane Yacht EquipmentLtd., Interstate Batteries, ITT/Jabsco, Kenyon Marine, Kohler Corporation, L Q.Moffit, Lasdrop Shaft Seal, Leeward Rigging, Lewmar Marine, Lirakis SafetyHarness Inc., Loos and Co., Lucas Marine, Paul Luke and Sons, Lunaire Marine,Mansfield Sanitary, Marine Power Ltd., Marine Vane Gear Ltd., Marlec, MarsElectronics, Martec, Max-Prop, MDC, Mercantile Manufacturing, MetalmastMarine, Micrologic, Morse Controls, Munster Simms Engineering Ltd (nowWhale), Navico, Navstar, Navtec, Newmar, Nicro Fico, NMEA, Norseman/Gibb,Onan, Parker Hannifin Corporation, Parker Industrial, PDC Labs International,Perkins Engines Ltd., Plastimo, Profurl, PYI, Raritan, Raytheon Marine Co.,Rolls Battery Engineering, RVG, S and F Tool Co., Sailomat, Sailtec, SandenInternational, Schaefer, Sea Frost, Sea Inc., SeaLand Technology, Shaft Lok Inc.,Shakespeare, Shipmate Stove Division, Signet Marine, Solar Power Corporation,South-wire Company, SpaCreek Inc., Sta-Lok, Stowe, Stream Stay, SurretteStorage Battery Co., Tartan Marine Co., Taylor’s Para-Fin, Tecumseh, TraceEngineering, Tracor Instruments, Universal Enterprises, VDO Marine, VernayProducts, Wagner Marine, Walker and Sons, Wallas Marin, Westerbeke

Generators, Whale, Whitlock Steering Systems, Wilcox-Crittenden, Wolter

Systems, and York

My editors at International Marine have been as helpful as ever Jim Sollers,illustrator extraordinaire, has done an astounding job interpreting my rough

sketches Molly Mulhern, the International Marine art and production director,has shown great patience with the rest of us and somehow kept the manuscriptand illustrations organized and on schedule

So you see, although it is my name on the cover, this book is really a

collective effort My thanks to everyone

Trang 30

Maine, September 1995

Trang 31

In the past two or three decades, boat equipment has taken a quantum leap incomplexity It is no longer possible to keep things operating with a monkeywrench, hammer, and grease gun More and more equipment needs specializedservicing, and the cost of professional help is going through the roof While thepublic may think that boatowners are rich, in reality most are middle-incomesalary earners who strain their budgets to support their boating habit The

boatowner of today with limited funds needs a good working knowledge of allsystems aboard, the ability to keep up with maintenance, and the means to

troubleshoot and repair a broad range of breakdowns

This book is intended to make these three objectives a realistic possibilitywith respect to the basic equipment found on most modern, midsized boats, bothpower and sail In developing its contents, the biggest problem I have had is indeciding where to draw the line between what a talented amateur in a jam canreasonably be encouraged to undertake, and leading people into trouble Since Ihave a high regard for most people’s capabilities, I have gone well beyond theinformation typically available to the general boating public

I have taken great pains to ensure the accuracy of this book All information isgiven in good faith Nevertheless, I must caution the reader: If you are in anydoubt about what you are doing, leave things alone! I cannot accept liability forany damage or injuries arising from the reader’s attempts to follow the

procedures in this book If you wreck a piece of equipment, sink the boat, or hurtyourself, the responsibility has to be yours

Now that I’ve gotten that off my chest, a word on how to use this book Thereare four distinct levels at which it can be useful:

• Many maintenance problems and equipment failures are the result of

inadequate or improper installations A quick skimming of the book,

skipping over the detailed sections on equipment repair, may well highlight anumber of potential difficulties on your boat and enable you to take

corrective action before something goes wrong This is especially relevantfor anyone buying a new boat Proper liaison with the boatbuilder can

eliminate most built-in problems at a fraction of the cost of a later cure

Trang 32

• When buying new equipment, a review of the pertinent section(s) will giveyou an idea of what can go wrong Although I don’t recommend one brandname over another, I can arm you with appropriate questions to ask aboutany brand This may save a lot of grief later

• Routine maintenance is covered in some detail in each chapter with an annualhaulout (winterizing) summary in Appendix A

• When equipment does malfunction or break down, the list of troubleshootingcharts on page viii and the index will point you to the relevant sections ontroubleshooting and repair

After reading this book, boatowners may think that maintenance and repair is

a full-time job in itself Sometimes it does seem like that But in reality, mostroutine maintenance procedures take little time The key is to be methodical andorganized And keep in mind that boat equipment likes to be used frequently Inthe marine environment, more things seize up from lack of use than from beingused Your boat will be least troublesome if you get the maintenance done, andthen go out on the water as often as possible

Happy Boating!

Trang 33

CHAPTER 1 Establishing a Balanced Battery-Powered Electrical

System

Trang 35

The marine environment is a terrible place for electricity To be trouble free,electrical circuits must be installed with great care and to the highest standards—topics that are dealt with in Chapter 4 But no matter how carefully an electricalinstallation is carried out, the entire system must be properly balanced in the firstplace, or it will soon become a source of endless problems and a constant drain

on the pocketbook

Because of improperly set up systems, many boatowners repeatedly findthemselves with dead batteries, outright battery failures, and lengthy chargingtimes Fixing immediate problems does nothing to resolve the overall imbalance

in the system, guaranteeing that the next difficulty is just around the corner Alarge number of boats come straight off the production line with these potentialproblems built in Thus the first requirement for electrical problem solving andrepair is to understand the peculiar needs of a boat’s DC electrical system and tomake sure the overall system is in balance This chapter takes a look at thesegeneral considerations; Chapter 2 looks at more complex systems; and Chapter 3deals with detailed maintenance, troubleshooting, and repair procedures forspecific pieces of DC electrical equipment Although I focus on 12-volt systems,all information is equally applicable to 24 or 32 volts

The Peculiarities of Boats

Trang 36

electrical needs, plus an extra margin to replace the energy the starter motorwithdrew from the battery The car’s electrical system runs on the power

supplied by the alternator, not that supplied by the battery Although startermotors use a tremendous amount of energy, they do so for a very brief period oftime, and thus pull next to nothing from a battery For example, a 400 amp

starter motor (a large starter motor) would consume 400 amp-hours of energy in

1 hour, but cranking it for 15 seconds (which is far longer than normal) drainsthe battery by only 400/(4 × 60) = 1.66 amp-hours, which is not very much! (Thedistinction between amps and amp-hours is drawn on page 13.) This drain isreplenished by the alternator in just a few minutes Under normal use, a car

battery is almost always fully charged, and the batteries do very little work Thisholds true for almost all cars, regardless of size, electrical complexity, or use

(The exceptions are some hybrids in which the engine shuts down when

stationary in traffic, and the car systems temporarily run off the batteries.) Ingeneral, the only variable from one car to another is the capacity of the alternator

—cars with high electrical loads need bigger alternators

Contrast this first with a sailboat The average boat spends most of its time in

a slip Periodically the owner cranks the engine, motors out of the slip, shuts theengine down, and goes sailing Apart from the time spent motoring, the boat’selectrical system runs directly off the battery The battery will be dischargedmore deeply than an automobile battery, while the engine will be run far lessthan an automobile engine, providing minimal charging time

Now consider the average powerboat The engine will be run for longer

periods of time than a sailboat’s, with usage patterns often similar to those of anautomobile But even so, many powerboats, especially cruising boats (notablytrawler yachts), will have extended periods when the engine is shut down, andthe boat’s electrical system is running off the batteries Although larger

powerboats may have a 24-hour-a-day generating capability, with a battery

charger left permanently on so that battery service closely resembles that of anautomobile, this scenario is not necessarily the norm (and in any case, is often apoor way to design a system—see Chapter 2) An increasing number of

boatowners with onboard AC generators and substantial power requirements arediscovering that with a DC-to-AC inverter (see Chapter 6), they can shut down

Trang 37

resembles that of cruising sailboats

What this all adds up to is that in contrast to automotive use, at some point intime almost all boats run their DC systems off the battery, deeply discharging it

As a result, the working environment for all the major DC system components—the battery, alternator, and voltage regulator—is very different from that found inthe automotive field, and yet, primarily for reasons of cost, it has been customary

to use transplanted automotive equipment in marine applications with little or nomodification Not surprisingly, this leads to numerous problems, most of whichhave their origins in the limitations of existing battery technology To see whythis is so, and how to correct problems, we need to delve into this technology

Batteries

How They Work

A battery is composed of one or more cells (Figures 1-2A and 1-2B) Each cell contains alternating negative and positive plates, between which are plate

separators (insulators) All the negative plates are connected together, as are all

the positive plates Each plate has a grid configuration, and within the grid is bonded the plate’s active material (Figure 1-3) The grid provides the physical

structure for the plate and the means for conducting electrons in and out of theplate The active material is the substance that produces the electrons

Trang 38

are six cells; within each is a series of alternating negative and

positive plates, each one isolated from its neighbors by intervening insulators, called separators The plates are immersed in a sulfuric acid solution The negative plates are connected with each other and with the negative terminal; the positive plates are collectively

connected with the positive terminal (Battery Council International)

Trang 39

automotive battery, except that everything is more heavy duty, with considerably more lead, and therefore capacity, in a given volume.

Trang 40

What is not built into the cell chemistry is the capacity of a cell (how many

electrons the cell can store), how fast the cell can deliver these electrons whenconnected to a load, and how fast it can be charged

Crudely speaking, capacity is a function of the amount of lead in a cell—thegreater the weight of lead dioxide and lead paste, the greater the storage capacity

A large, thick plate will produce the same voltage as a small, thin plate, but willstore many times more electrons

The ability of a plate to give up its stored energy depends on the ability of theacid in the electrolyte to react with the active material in the plate The activematerial is made porous so that the acid can filter (diffuse) through the plate,allowing water to percolate out and fresh acid to percolate in during discharges,and the reverse to happen during charges The thicker the plate and the denserthe active material, the slower the process of percolation, and as a result, theslower a battery will give up its stored energy, and the slower it can be charged.When a battery is put under a heavy load, the electrolyte will first react withthe accessible (surface) areas of the plates But once these have given up theirstored energy, the rate at which electrons can be released from the inner areas ofthe plates slows down, causing the voltage to fall off This does not necessarilymean that the battery is dead If you rest it, allowing time for the water to diffuseout of the plates and fresh acid to filter in, the voltage will recover as fresh areas

of active material are brought into service This is why, if a car is cranked untilthe battery dies and then left for a short period of time, the battery will frequentlyrecover and crank the engine again—the acid has diffused to unused portions ofthe plates, providing a fresh burst of energy

Định dạng
Số trang	1.818
Dung lượng	38,25 MB