Preliminary Design Review 1 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

 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 3 (ARD) has requested improvement of capacity retention over the course of the propulsion batteries life cycle.

 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

6 1. CC(45A/string) until 2.35V/cell 2. CV until 6.25A/string 3. CC for 3 hours with 2.50V/cell voltage limit2.50V/cell voltage limit Main Charge Overcharge  V batteries divided into 4 parallel strings  Approximately 15min checks  Batteries 4 years(approx. 80% capacity)

 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 charge ~ 12 hours  Two 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 10 ΔVoltage

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 12...

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 13

 Fast Charging Start with large current pulses (up to 4C) Monitor voltage and step down current each time voltage limit is reached 14

15  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

16 ItemMethodWeight CI/CVZDVCIFC Cat Caps 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?????8% Reduction in Charge time?????1% Cost of Implementation?????5% Long term Costs reduction?????25% Higher score is better % 39%

 CI and ZDV require testing  Charge module capabilities unknown  Testing is required to determine charge time  Long term effects to be determined 17

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 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 19

20 ItemDescriptionQty Base Cost Total BatteriesNew LSV2 battery (2025 Lead) 6 $ $2, Charge/Discharge System Arbin BT2000 / AeroVironment ABC- 150 or ABC-5 1 PENDING Catalyst CapsOxygen Recombination Catalyst 3 $35.00 $ Total PENDING

CONTINUED USE OF SYSTEM BENEFITS OF NEW SYSTEM  $593,000/4 years for Main battery replacement  Labor costs of replacement process  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 21

 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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