Transcript Team AutoVolt - University of Idaho

Preliminary Design Review
Team Members:
Chris Douglas – Project Manager
David Hooker – Lead Research, Webmaster
James Randall – Liaison, Budget Manager
Sponsors:
Naval Surface Warfare Center: Acoustic Research
Detachment, Bayview ID
Advisor:
Dr. Gregory Donohoe, University of Idaho
Mentor:
Dr. Herbert Hess, University of Idaho
1
 Problem
Statement, Specifications,
Deliverables
 Current System, Situation
 Design Concepts
 Trade Study
 Equipment
 Return on Investment
 Timeline/Future Work
 Challenges
2
 The
Large Scale Vehicle 2
(LSV2) is an autonomous
electric submarine used
to study acoustic
properties of propulsion
systems. The Acoustic
Research Detachment
(ARD) has requested improvement of
capacity retention over the course of the
propulsion batteries life cycle.
3

Document current charging configuration with
scheme advantages and disadvantages

Research of potential changes to system to extend
capacity retention

Develop a cost-benefit analysis of implementing a
new charging scheme

Produce computer simulations of current and
alternate configurations

Construct lab scaled model of current and alternate
schemes
4
Current
System Report
Trade Study
Selected Choices Summary
Overview of Rejected Proposals
Cost-Benefit Report
Lab Test Report
Proof of Safety Report
Computer Simulation
5



1680 2V batteries divided into 4 parallel strings
Approximately 15min checks
Batteries decommissioned @ 4 years(approx. 80% capacity)
Main Charge
Overcharge
1. CC(45A/string)
until 2.35V/cell
2. CV until
6.25A/string
3. CC for 3 hours with 2.50V/cell voltage limit
2.50V/cell voltage limit
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 Human
charge control can lead to
undercharge or overcharge
• Both OC and UC can lead to battery life degradation
 Charging infrastructure maxed
• Chargers working at max current
• wiring from chargers to sub at max current
• Power grid already overloaded
 Aux. battery
 Two
charge ~ 12 hours
types of chargers readily available
7
 Extend
useful life of batteries
• Reduce expenses over long term
• Reduce submarine downtime over long term
resulting in higher return for taxpayer dollars
 Reduce
the capacity loss of batteries
over current service life
• Maintain underway duration over service life
8
 Automate
System
• Free up technicians for other purposes
• Reduce risk of error of human control
 Improve
Oxygen recombination
efficiency(ORE)
• Reduce outgassing
• Decrease energy waste
9

Zero Delta Voltage (ZDV)
• Concept
 Max current charges until 70% return of charge
 Constant Current (C/5) until ZDV is reached
 ZDV is defined as a limit in change in voltage between two
readings
 A reading is defined as 30 second averages of voltage readings
Zero Delta Voltage
Voltage (V)
2.75
2.55
2.35
ΔVoltage
2.15
1.95
Time (s)
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• Pros
 Accurately detects end of charge cycle
 Reduces human error during charge cycle
 Reduces possibility of detrimental
undercharge/overcharge
 Possible 100% increase of battery life
• Cons
 Will need to be tested on multiple battery system
 Variable voltage termination limit over life of batteries
11

Current Interrupt (CI)
• Concept
 Used after primary charge has completed (overcharge)
 Charge algorithm consists of a pulsed current
 CI is employed until 10% overcharge has been achieved
Current (C)
CI Overcharge
1.5
1
...
0.5
0
0
20
40
60
80
Time (s)
100
120
140
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• Pros
 Allows cooling period for batteries preventing
excessive thermal degradation
 Allows for chemical reactions to stabilize during the
off period leading to higher ORE
 Can be used independently of main charge method
• Cons
 Unknown change in charge time
 Setup of system may be complex
 Normally employed after a fast charge algorithm has
delivered 100% of depleted charge
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 Fast
Charging
• Start with large current pulses (up to 4C)
• Monitor voltage and step down current each
time voltage limit is reached
14
 Pros
• Is an extremely fast charge method
• Increases capacity retention throughout life
 Cons
• Requires enormous amounts of current (up to
600A)
• Generates large amounts of heat
15
Item
Software Complexity
Power Requirements
Shore Power Considerations
Rewiring of both Barge and Vessel
Difficulty of Implementation
Charge available for Underway
Expected EOL Capacity
External Interfacing of Controls
Reduction in Charge time
Cost of Implementation
Long term Costs reduction
Higher score is better
Method
CI/CV ZDV
0.27 0.24
0.45 0.54
1.5 1.5
0.2 0.18
0.45 0.35
1.2 1.6
0.3 0.6
?
?
?
?
?
?
?
?
4.37 5.01
CI FC
0.2 0.2
0.3 0.1
1.5 0
0.2 0
0.4 0.2
1.8 2
0.9 1
? ?
? ?
? ?
? ?
5.2 3.4
Weight
Cat
Caps
3%
0.3
6%
0.6
15%
1.5
2%
0.2
5%
0.4
20%
1.6
10%
0.8
8%
?
1%
?
5%
?
25%
?
5.4 100%
39%
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 CI
and ZDV require testing
 Charge
module capabilities unknown
 Testing
is required to determine charge
time
 Long
term effects to be determined
17
18
 Software
capable of accurately simulating
cycle life has yet to be discovered
 State
of health simulation is unfeasible at
this time due to:
• Varying discharge rates during each test run
• Varying internal characteristics and chemical
composition over battery life
• Varying and unknown cell temperatures for charge
and discharge cycles
 Development
contingent upon lab data
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Item
Description
Batteries
Charge/Discharge
System
Catalyst Caps
New LSV2 battery (2025 Lead)
Arbin BT2000 / AeroVironment ABC150 or ABC-5
Oxygen Recombination Catalyst
Qty Base Cost Total
6
$340.00 $2,040.00
1
3
PENDING PENDING
$35.00
$105.00
Total PENDING
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CONTINUED USE OF SYSTEM


$593,000/4 years for
Main battery
replacement
Labor costs of
replacement process
BENEFITS OF NEW SYSTEM


Extending battery service
life by at least 50% yields
savings of $50,000/year
(not including man hours)
Length of underways can be
maintained over longer
period of time yielding more
data collected per run
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 State
of health simulations non-existent
 Time
constraints for cycle life testing
 Managing
multiple test cases
 Access
to charger control module
 Access
to /Purchase of testing equipment
22

Schedule with design of charge/discharge system

Alternative budget to be determined
23
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