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`
`Innovations in Design:
`1-993 Ford Hybrid
`Electric Vehicle
`Challenge
`
`SP-980
`
`• G&.08Al M0811.11Y 00.TABA.SE
`
`All SAE pap,,rs, standsrrJ$, and S818Cl8d
`books are ab$ttaC1ed and indexed in the
`Global MobHity Oa/JlbaS8.
`
`Published by:
`Society of Automotive Engineers, Inc.
`400 Commonwealth Drive
`Warrendale, PA 15096-0001
`USA
`Phone: (412) 776-4841
`Fax: (412) 776-5760
`February 1994
`
`-~ '
`
`• &1M&'R lJN"1rns1lY LtRnAnv
`I.I"\
`I¥ ir;rt .. ,
`
`r\
`
`_
`
`BMW1023
`Page 1 of 11
`
`

`

`Permission to photocopy for internal or personal use, or the internal or personal use of specific
`clients, is granted by SAE for libraries and other users registered with the Copyright Clearance
`Center (CCC), provided that the base fee of $5.00 per article is paid directly to CCC, 222 Rosewood
`Drive, Danvers, MA 01923. Special requests should be addressed to the SAE Publications Group.
`1-56091-388-6/94$5.00.
`
`I ,.
`
`'
`
`No pa~ of th(s publicatio~ may be reproduced in any form, in an electronic retrieval system or
`otherwise, without the pnor written permission of the publisher.
`
`ISBN 1-56091-388-6
`SAE/SP-94/980
`Library of Congress Catalog Card Number: 93-84469
`Copyright 1994 Society of Automotive Engineers, Inc.
`
`Positions and opinions advanced in this pa(cid:173)
`per are those of the author(s) and not neces(cid:173)
`sarily those of SAE. The author is solely
`responsible for the content of the paper. A
`process is available by which discussions will
`be printed with the paper if it is published in
`SAE Transactions. For permission to pub(cid:173)
`lish this paper in full or in part, contact the
`SAE Publications Group.
`
`Persons wishing to submit papers to be con(cid:173)
`sidered for presentation or publication through
`SAE should send the manuscript or a 300
`word abstract of a proposed manuscript to:
`Secretary, Engineering Meetings Board, SAE.
`
`Printed in USA
`
`FORWARD
`
`The papers in thjs Special Publication were originally developed as submittals for the Technical
`Report event at the 1993 Hybrid Electric Vehicle (REV) Challenge. Held June l through June 6 in
`Dearborn, Michigan, the 1993 HEV Challenge was sponsored by a partnership of the Ford Motor
`Company, the U. S. Department of Energy (DOE), and the Society of Automotive Engineers (SAE).
`This competition was another in a series of Engineering Research Competitions supported by DOE and
`part of the Collegiate Engineering Design Competition Series sponsored by SAE. The papers presented
`here are enhanced and expanded versions of those prepared in advance of the competition by teams of
`participating student engineers. They describe the design elements and construction details of the largest
`field ofHEVs yet assembled from some of the best engineering schools in North America. SpeciaJ thanks
`and recognition are extended to the Ford Motor Company for its outstanding support of this competition.
`
`Thirty colleges and universities from the U.S. and Canada were selected to participate in this
`HEV competition to explore the potential of this cutting-edge technology through a Request for
`Proposals process initiated in January, 1992. A letter announcing and soliciting interest in the
`competition was sent to all accredited engineering programs and two-year technical schools in both
`countries. It described the nature of the events and the two available classes in the competition: one
`required constructing a HEV from the ground-up and the other required converting a 1992 Ford Escort
`Wagon to hybrid operation. Sixty-seven schools submitted proposals that were evaluated by a team of
`judges from industry and government experts. From these proposals, twelve schools were selected to
`participate in the Ground-Up class and eighteen schools in the Escort Conversion class. Twenty-six of
`these schools were able to pass technical and safety inspections and qualify for the actual competition in
`June, 1993.
`
`The Challenge consisted of a series of static and dynamic events designed to assess the quality of
`the student's efforts. The dynamic events measured the performance of the vehicles constructed by the
`teams of student engineers and the static events
`evaluated their engineering and communication
`skills. Each event was assigned a portion of the
`1,000 available points in the competition according
`to Table 1. The Technical Report event served both
`as a way to emphasize the importance of
`communicating the content of and rationale for the
`team's design as well as to document the
`specifications of the competing vehicles. The
`Report was due one month before the competition
`to allow time to judge them. Teams of judges were
`assembled from industry and government sources to
`read and score the reports. At least five judges
`evaluated each report; their scores were normalized
`to a 75 point scoring range and then averaged to
`determine a rank order of schools in each class.
`Points were then assigned to the schools according
`to a pre-published schedule that allocated points
`according to the vehicle class and the school's
`overall rank.
`
`Table 1. Competition Points
`Event Description
`Technical Report
`Engineering Design Event
`Oral Presentation
`Acceleration Event
`Emissions Event
`Commuter Challenge Event
`APU Efficiency Event
`Range Event
`Electric Efficiency Event
`Overall Efficiency Event
`Cost Assessment Event
`Total Points
`
`Points
`75
`150
`50
`100
`150
`150
`35
`75
`35
`55
`125
`1,000
`
`BMW1023
`Page 2 of 11
`
`

`

`The complete results from the 1993 HEY Challenge, including the scores from the Technical
`Report event, can be found in Table 2 for the Ground-Up Class and Table 3 for the Escort Conversion
`Class. Many technical achievements and peiformance benchmarks for HE.Vs were set during this
`competition; a complete description of the competition's structure and outcomes, as well as an analysis of
`the results, will be published as a separate SAE paper.
`
`On behalf of all the sponsors of the 1993 HEY Challenge, I thank you for your interest in the
`1993 HEY Challenge. The impressive accomplishments of the teams of student engineers contained in
`this publication speak for themselves. If the reader has any questions concerning the organization of the
`competition or its outcomes, please contact me at 9700 S. Cass Avenue, Building 362-B209, Argonne,
`Illinois, 60440., USA.
`
`Robert P. Larsen
`
`Center for Transportation Research
`
`Argonne National Laboratory
`
`Table 2.
`
`Final Scores for the
`1993 Ford/DOE/SAE
`REV Challenge
`
`Ground-Up Class
`
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`California Polytechnic - Pomona
`California Polytechnic-San Luis Obispo
`Cornell University
`Lawrence Technological University
`Michigan State University
`New York Institute of Technology
`University of California - Davis
`University of California - Santa Barbara
`University ofldaho/Washington State
`University of Tennessee
`University of Texas - Arlington
`University of Tulsa
`
`18
`14
`37
`26
`62
`11
`51
`75
`8
`43
`11
`22
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`73
`44
`150
`124
`0
`87
`36
`102
`22
`61
`29
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`41
`24
`34
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`7
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`82
`41
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`79
`31
`84
`63
`0
`20
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`42
`106
`68
`99
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`77
`85
`48
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`84
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`52
`124
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`61
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`87
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`35
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`62
`26
`51
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`75
`43
`31
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`22
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`12
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`27
`45
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`19
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`16
`55
`22
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`83
`55
`125
`66
`60
`25
`108
`93
`44
`74
`25
`49
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`335
`317
`750
`482
`65 1
`41
`675
`478
`447
`525
`114
`357
`
`BMW1023
`Page 3 of 11
`
`

`

`Table 3.
`
`Final Scores for the
`1993 Ford/DOE/SAE
`BEV Challenge
`
`Ford Escort Conversion
`Class
`
`California State University -
`Northridge
`Colorado School of Mines
`Colorado State University
`Concordia University
`Jordan College Energy Institute
`Pennsylvania State University
`Seattle University
`
`Stanford University
`
`Texas Tech University
`United States Naval Academy
`University of Alberta
`
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`14
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`18
`20
`48
`28
`14
`25
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`16
`38
`
`81
`50
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`53
`61
`75
`
`47
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`44
`87
`94
`
`460
`417
`651
`301
`(327) 81.2
`602.5
`
`360
`
`(222) (21.5)
`(10) 460
`774
`
`TABLE OF CONTENTS
`
`Design Reports
`
`University of Alberta ........................................................................................................ 1
`
`University of California, Davis ....................................................................................... 13
`
`University of California, Irvine ....................................................................................... 31
`
`University of California, Santa Barbara ........................................................................ 45
`
`California State University Northridge .......................................................................... 51
`
`California State Polytechnic, Pomona .......................................................................... 61
`
`California Polytechnic State University, San Luis Obispo .......................................... 71
`
`Colorado School of Mines ............................................................................................. 79
`
`Colorado State University .............................................................................................. 87
`
`Concordia University ..................................................................................................... 99
`
`University of California - Irvine
`
`University of Illinois
`
`University of Wisconsin
`
`Washington University -
`St Louis
`Wayne State University
`Weber State University
`
`West Virginia University
`
`21
`
`65
`
`57
`
`0
`
`28.5
`16
`
`42
`
`0
`
`150
`
`68
`
`0
`
`30
`93
`
`76
`
`7
`
`31
`
`38
`
`6
`
`14
`50
`
`22
`
`0
`
`52
`
`68
`
`0
`
`46
`59
`
`44
`
`0
`73
`
`0
`
`0
`
`0
`40
`
`0
`0
`
`106
`131
`
`48
`
`50
`115
`
`84
`
`0
`9
`
`0
`0
`
`16
`18
`
`10
`
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`27
`
`14
`
`0
`
`51
`65
`
`21
`
`0
`12
`
`18
`
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`
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`31
`
`18
`
`0
`42
`
`0
`
`0
`
`34
`31
`
`55
`
`25
`
`57
`
`41
`
`0
`
`53
`
`558
`
`304
`
`6
`
`87 (240) 232.7
`125
`734
`
`70
`
`490
`
`Cornell University ......................................................................................................... 115
`
`University of Idaho and Washington State University ............................................... 127
`
`University of Illinois at Urbana-Champaign .............................................................. 141
`
`Jordan College Energy Institute .................................................................................. 157
`
`Lawrence Technological University ............................................................................ 163
`
`Michigan State University ........ : .................................................................................. 175
`
`New York Institute of Technology .............................................................................. 191
`
`Seattle U niverslty ......................................................................................................... 207
`
`Stanford University ..................................................................................................... 219
`
`University of Tennessee .............................................................................................. 229
`
`University of Texas at Arlington .................................................................................. 243
`
`Texas Tech University ................................................................................................. 257
`
`University of Tulsa ....................................................................................................... 265
`
`BMW1023
`Page 4 of 11
`
`

`

`I
`
`United States Naval Academy ..................................................................................... 2n
`
`Wayne State University ................................................................................................ 289
`
`Weber State University ................................................................................................ 303
`
`University of Wisconsin-Madison ............................................................................... 311
`
`West Virginia University .............................................................................................. 321
`
`BMW1023
`Page 5 of 11
`
`

`

`I•
`
`!:
`
`United States Naval Academy, AMPhibian
`Gregory W. Davis, Gary L. Hodges, Frank C. Madeka, Jason L. Pike,
`Joseph Greeson, Dennis Klein, and John Boone
`United States Naval Academy
`
`ABSTRACT
`
`The U. S. Naval Academy's entry for the Hybrid Electric
`Vehicle Challenge is a 1992 5-door Ford Escort LX Wagon with a
`manual transmission which has been converted to a series drive
`hybrid electric vehicle(HEV). A DC motor, coupled to the existing
`transaxle provides propulsion. Lead-acid batteries are used to store
`the electrical energy. The auxiliary power unit(APU) consists of a
`small gasoline engine connected to a generator. The AMPhibian is
`designed to be a feasible HEV, for use in near term applications. To·
`accomp~sh this, all components are based upon existing technology.
`Further, this vehicle was designed to retain, to the greatest degree
`possble, the basic driving characteristics of a conventional gasoline
`powered vehicle. The major performance design goals for the
`AMPhibian include 1) the ability to travel 64 Km as a zero emissions
`vehicle(ZEV) using battery power alone, 2) operating in hybrid mode,
`the ability to travel 320 Km while meeting the transttional low
`emissions vehicle(TLEV) air pollution standards, 3) achieve a time of
`under 15 seconds when accelerating from O to 70 Kph, and 4) climb
`a minimum of a 15% grade.
`
`OVERVIEW
`
`The USNA midshipmen accepted the HEV Challenge as an
`extension of their commitment to serve their country -- in this case,
`to help America preserve its resources.
`The vehicle name,
`AMPhlbian, was chosen by the midshipmen because, just as a real
`amphibian spends time both on land and in the water, by analogy
`the vehicle will operate using electrical energy from the battery
`system, and at other times with electrical energy derived from the
`gasoline powered generator. As a reminder that ~ectricity will be
`the primary power source for the vehicle, the first three letters of
`AMPhlbian were capitalized to represent the ampere, the basic unit
`of electric current. Finally, the name also acknowledges the mHitary
`role provided by the Navy and Marine Corps amphibious team.
`
`The dual nature of a hybrid electric vehicle also led the
`midshipmen team to choose ''96" as the vehicle's number. The
`number can be read from two different directions with the same
`resul~ just as the AMPhibian can be easily driven by stored electrical
`energy from the batteries or by generated electrical energy from the
`auxiliary power unit.
`
`DESIGN OBJECTIVES
`
`The U. S. Naval Academy HEV, AMPhibian, was designed to
`be a feasible HEV for use in near term applications. The challenge
`involves many aspects including cost effectiveness, acceleration,
`range, safety, and emissions. These design goals were considered
`when designing the vehicle.
`COST · Since
`to be
`the AMPhibian was designed
`economically feasible, minimizing cost was considered to be a map(cid:173)
`design goal. All design decisions were made only after the
`associated costs were analyzed. To help attain this goal, all
`components were to be based upon existing, available technology.
`PERFORMANCE AND EMISSIONS • The major performance
`and emissions design goals for the AMPhibian include 1) the ability
`to travel 64 Km as a zero emissions vehicle(ZEV) using battery
`power alone, 2) operating in hybrid mode, the ability to travel 320
`Km while meeting the transitional low emissions vehicle(TLEV) air
`pollution standards, 3) achieve a time of under 15 seconds when
`accelerating from Oto 70 Kph, and 4) climb a minimum of a 15o/o
`grade. The vehicle was also to maintain driving characteristics as
`similar to that of conventional gasoline powered vehicles as
`possible(e.g. one brake pedal, shift gears normally, etc.).
`RELIABILITY AND DURABILITY • The AMPhibian was to
`have reliability and durability similar to that of a conventional
`gasoline powered vehicle. Using existing components woud not
`only help to limit the costs, but also to help ensure reliable and
`durable operation of the vehicle.
`SAFETY • Occupant safety was a prime concern. The frontal
`impact zone and original vehicle bumpers were to be maintained to
`provide sufficient collision protection. The original power-assisted
`
`277
`
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`
`

`

`... .
`
`~.
`I:
`
`I, .. ;
`
`braking system was also to remain intact to ensure proper braking.
`A fire suppression system was to be added to the vehicle and
`battery compa11ments, as well as to the engine bay to minimize the
`chances of injury and equipment damage. Due to the additional
`vehicle weigh~ the roof structure was to be augmented to provide
`additional protection in case of a vehicle roll-over. Finally, the
`competition rules required the use of a five point harness system for
`both the driver and passenger.
`WEIGKT • One major disadvantage of electric vehicles has
`traditionally been the large weight due to the propulsion batteries
`required to provide the energy storage capabifity for extended range.
`An advantage of the HEV concept is to allow for less energy storage
`capability of the batteries by replacing some of these batteries with a
`small auxiliary power uni(APU) which provides the equivalent
`amount of energy with less weight However, battery weight was
`still considered to be a major concern, requiring the team to consider
`all options for reducing vehicle weight. The AMPhibian was to be
`designed to weigh less than the gross vehicle weight rating(GVWA)
`of the 1992 Escort LX Wagon plus an additional 10%. This results
`in a maximum allowable vehicle mass of 1729 kg. Further, to
`maintain acceptable handling, the side-to-side bias must remain
`within 5% of neutral, and the front-to-rear bias must not drop below
`about 40%/60%.
`PASSENGERS AND CARGO • The HEV was to carry one
`driver and one passenger, along with a volume of cargo(50 cm by
`100 cm by 25 cm). The total combined weight of people and cargo
`was a minimum of 180 kg.
`BATTERY CHARGING • The HEV charging system was
`designed to recharge the battery pack in six hours. This should
`reduce daytime charging demand on electrical utilities. Daytime
`charging, tt necessary, could be accomplished using the APU. The
`charging system was to accept either 110V or 220V, 60 Hz AC
`power.
`STYLING • Vehicle styling changes were to be minimized to
`maintain continuity with existing vehicle designs. No external glass
`or body sheet metal was to be modified except to provide additional
`ventilation.
`
`VEHICLE DESIGN
`
`The relationship of the design goals was studied, and
`compromises were made to provide near optimal system design,
`given the severe budgetary and time constraints. This process
`resulted
`in
`the selection and design of the major ~ehicle
`components. The following discussion details the design decisions,
`this is followed by a summary table of the · actual vehicle
`components.
`'
`"
`POWERTRAIN • The AMPhibian is propelled using a series
`drive configuration. That is, the only component that is mechanically
`connected to the drive-train of the vehicle is the electric motor. This
`arrangement is depicted in figure 1, located in the appendix. This
`arrangement was considered to be superior to the parallel drive
`arrangement, in which both the electric motor and the APU can
`propel the vehicle, for the following reasons. The series drive would
`require less structural change to install, and thus provide a lower
`The parallel drive system would also require a more
`cost.
`sophisticated control system to minimize driveability problems such
`as those associated with the transition from electric vehicle(EV)
`mode to hybrid electric vehicle(HEV) mode. This would, again,
`
`result in higher cost, and, possibly, reliability problems due to the
`added complexity. The parallel drive is enticing because it has the
`potential to provide improved acceleration since both the APU and
`the electric motor are used to propel the vehicle. However, when
`the battery is discharged, the parallel system cannot easily be used
`to recharge the system, thus the potential for daytime use of
`electrical energy for charging is increased. Overall, the series drive
`was seen to be the best choice to meet the design goals.
`The conversion to a series drive system required the removal
`a the standard Escort engine. Since the Escort has front-wheel
`drive, the standard engine is mounted transversely in a transaxle
`arrangement. Thus, the transaxle was left intact so that a new axle
`would not need to be designed. The electric motor was attached
`direcdy to the existing bell-housing and flywheel. This arrangement
`also allows full use of the existing transmission, thus allowing for
`variable gear ratios. This was considered an advantage since it
`would allow the electric motor to be operated closer to its preferred
`operating speed over varying vehicle speeds.
`Prior vehicle testing and simulation indicated that the vehide
`would require a power of approximately 9 kW in order to maintain a
`steady 80 Kph. Acceleration from a stand still to 72 Kph in less than
`15 seconds would require a peak power of 32 kW(at approximately
`35 Kph) for a short duration. Motor controller cost and availability
`became the critical design factor for the selection of both the type of
`motor and the system operating voltage. The use of an AC motor
`was nvestigated due to its inherendy higher power density
`compared to a DC system. However, it was rejected due to the
`cost availability, size, and weight of the associated motor controller.
`A series wound, 15.2 kW(@ 90 VDC) DC motor was chosen instead
`since DC motor controllers are more widely available, less cosdy,
`and lighter in weight The combination DC motor and controller
`weighs approximately 82 kg, the engine that was removed weighed
`113 kg, thus resulting in a net weight savings of 31 kg. Although the
`steady state rating is less than the peak incurred during the
`acceleration, the motor can provide a peak power 2·3 times its
`steady state rating for short duration. To provide maximum torque, a
`high system voltage is required. Cost, size and the ready availability
`of a proven motor controller dictated the controller choice. A
`controller rated at 120 VDC(160 V peak) was chosen, thus this
`determined the system operating voltage.
`BATTERY SELECTION· USNA AMPhibian has two battery
`power systems. One system is at 12V and one at 120V. The 12V
`system is used to power the 12V lighting and accessories. The
`120V primary battery powers the prime mover and supplies power to
`recharge the 12V battery.
`USNA AMPhibian battery selection was overwhelmingly driven
`by cost considerations. Secondary considerations included: 1) the
`HEV Challenge constraint of 400V or less battery stack voltage, 2)
`the motor controller rating of 120V, 3) the HEV Challenge constraint
`of no more than 20 kW-hr capacity at a 3 hr discharge rate, 4) the
`gross vehicle weight
`rating constraints and 5) practical
`considerations.
`In general, an inexpensive, small, lightweight
`battery having high specific power and high specific energy is
`desired for use in the AMPhibian. Additional considerations included
`the desire to maximize voltage thereby minimizing 12R losses due to
`lower operating currents. Also, to help to maximize KW-hrs
`capacity, and, therefore, ZEV capabilities, the amp-hr battery rating
`should be maximized. Since the maximum rating for the motor
`controller is 120V, 120V was selected. This enabled, AMPhibian to
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`determine an order-of-magnitude calculation of the costs of batteries
`having characteristics superior to those of conventional lead-acid
`batteries. Results of this analysis lead the AMPhibian design team
`to limit battery selection considerations to off-the-shelf lead-acid
`batteries. For example, Nickel-Iron batteries were found at a cost of
`$1800 per six volt battery or $36,000 for a 120V battery stack.
`Nickel-Cadmium were found at a cost of $964 per six volt battery or
`$19,280 for a 120V battery stack. Both estimates far exceeded
`AMPhibian budget constraints, hence, the self-imposed limitation to
`lead-acid.
`Discussions with EV enthusiasts,· battery suppliers,·· and
`professional EV converters"' helped team AMPhibian to focus on
`several battery features. These features included the following: wet(cid:173)
`celled batteries can provide a slightly higher capacity, are typically
`less expensive than, and require a less complex charging system
`than gel-celled batteries; however, gel-celled batteries do require
`less maintenance than wet-celled batteries; "flag· or "L • type
`tenninal configurations have proven to be more reliable and durable,
`and provide greater contact surface area(helping to minimize
`corrosion problems) than standard automotive post type tenninals.
`Ideally,
`the battery stack would be composed of individual,
`replaceable cells to facilitate replacement of only bad cells as
`opposed to the replacement of entire multi-celled, batteries having
`only one bad cell. AMPhibian decided to go with 12V batteries for
`cost and weight considerations.
`The task of battery selection was complicated due to the
`general
`lack of published, comprehensive,
`technical battery
`performance data covering an extensive number of battery models
`and manufacturers which had been verified by an independent
`source. This limited information is shown in the following figures.
`From figures 2 and 3 of the appendix, the selection of batteries was
`reduced by eliminating those batteries exceeding 20 kW-hrs at a 3
`hour discharge rate and those batteries which would exceed an
`absolute maximum battery stack weight allocation of 500 kg. With
`the number of batteries reduced, batteries were compared on a
`specific volume to weight and capacity to weight basis, see figures 5
`and 6 of the appendix. Figure 7 shows the energy capacity per unit
`volume. Based upon the evaluation of this limited data, and relying
`upon the advice of EV owners and professional EV manufacturers,
`the Trojan 5SH(P) battery appeared to be the best choice . The
`Trojan 5SH(P) battery is a deep-cycle, wet-celled, 12V battery. The
`"L" type tenninals were selected for this application. With the
`primary battery selected, the 12V system needed to be defined and
`selected.
`Several approaches were considered to power the 12V
`system. This included the extremes of using the existing 12V
`system, as is, or converting all 12V components to 120V.
`Engineering judgment indicates the latter option is not practical.
`One approach for providing power to the 12V system was to utilize
`the output of one twelve volt battery from the 120V stack. This
`approach has the advantage of simplicity. One disadvantage of this
`approach is that, using the existing 12V components which are
`grounded to the chassis, means that the battery stack is no longer
`
`• Mr. David Goldstein, President, Electric Vehicle Association
`of Greater Washington, D.C., private conversations.
`" Mr. Bill Kump, GNB Incorporated, Automotive Battery
`Division, private conversations.
`... Mr. Douglas Cobb, President, Solar Car Corporation,
`private conversations.
`
`279
`
`electrically isolated from the chassis and, thus, the chance of injury
`in the event of fa~ure is increased. Another problem, is that, since
`the batteries are connected in series, if the battery used for the 12V
`system fails, the whole battery stack will become inoperable. The
`chance of battery failure can be reduced by inserting a hgher amp(cid:173)
`hr rated battery into the 120V stack to compensate for the added
`use. The disadvantage is that this local change to the series of
`batteries imparts an unknown on
`the primary battery stack
`performance {i.e., internal impedance and resistance). This lead to
`the decision to have two separate battery systems, a 120V primary
`system and separate 12V system.
`Several options were considered for the 12V system. One
`option was to incorporate a single, independent high amp-hr rated
`battery required to provide several hours at a relatively high
`discharge rate (e.g., driving at night and in rain/use of head lights
`and wipers). This battery would then be recharged externally during
`refueling and/or recharging. This option was rejected due to the
`resulting high weight of the battery. A DC/DC converter, powered by
`the 120V stack, could be used to meet all of the 12V demand.
`However, this converter must meet the peak 12V load, which is
`estimated to be 210 amps during starting of the APU. This option
`was rejected due to the heavy weight and size of this converter. A
`DC/DC converter, sized to handle the sustained accessory loads
`under moderate to heavy use, was incorporated in parallel with a
`small 12V battery, sized to accommodate the APU starting loads.
`This design saves both space and weight. The estimated sustained
`load encountered during moderate to heavy accessory use is 20A.
`However, a 30 amp DC/DC converter was selected to accommodate
`the future addition of a climate control system for the passenger
`compartment. The APU starter requires a battery rated at 210
`cranking amps. The ultra light Pulsar Racing Battery, offered by
`GNB Incorporated, was used since this battery weighed only 4.5 kg,
`or approximately 50%
`less than other conventional
`lead-acid
`batteries, and provides 220 cranking amps. AMPhibian's net 12V
`accessory system, occupies the same volume as the OEM 12V
`battery, but weighs approximately 9.5 kg less than the OEM battery
`alone.
`BATTERY COMPARTMENT • The hybrid electric vehide
`battery compartment is required to support, protect, and ventilate ten
`12V batteries .
`The competition requirements dictate a container that could
`withstand a vehicular roU over, with a complete ventilation unit
`isolated from any passengers. When the design was started it was
`not certain which batteries would be chosen due to available funds.
`Therefore, a design was based upon a single base plate in which a
`variety of batteries could be supported, as shown in figure 8 of the
`appendix. Weight balance calculations were made and it was
`determined that the battery compartment should be placed as far
`forward as the existing internal features would allow.
`The next step was a calculation of impact forces for a thirty(cid:173)
`five mile an hour frontal impact. This velocity was chosen to
`coincide with the speed used in frontal impact barrier testing.
`Calculations made under these conditions were used to select the
`size of bolts needed to secure the base plate. Once the base plate
`was built, additional structure was welded and bolted in order to
`pmvide a sealed enclosure. The battery compal1ment contains two
`grid structures. These structures provide lateral, longitudinal and
`vertical support. Additionally, they maintain spacing which is
`needed to allow ventilation of the batteries. The upper grid structure
`
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`was also designed to facilitate electrolyte servicing while the
`batteries are secured. the top of the battery enclosure was