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Liquid Reserve Fuze Batteries: Trying to Move Beyond The Status Quo

Jeff SwankUS Army Research Laboratory

CREB Munitions Batteries Workshop7 December 2016

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• Some quick notes• Technology and industrial base timeline• Challenges encountered (technical and otherwise)• Attempts to address those challenges• Going Forward

Outline

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This presentation focuses on liquid-electrolyte reserve batteries used in electronic fuzing applications (ARDEC, Picatinny Arsenal)

• Typically <10 watts required for up to 200 seconds, sustained output• Typically require very fast rise times (50-500 ms) over the entire

operating temperature range• Typically subjected to high rates (up to 18,000 RPM or more) of

rotation• Must survive significant launch accelerations

• Up to 30,000 G for large-caliber applications• Up to 100,000 G for medium-caliber applications

This presentation is not intended to address the much larger, more complex liquid reserves used in AMRDEC and MDA applications

Some Quick Notes

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Battery Examples

Large caliber fuze battery (MOFA)

Medium caliber fuze battery (XM80)

AA

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MOFA Cutaway Illustration

Multi-Option Fuze for Artillery (MOFA) battery105- and 155-mm rifled artillery applications

Endplate

Case

Cell Cup

Cell Stack

Positive Pin(GTM Seal) Terminal Plate

(+)(-)Spring

Interlock Pin(2 Places)

Cutter

Drive DiskReservoir

Spacer

Ball Seal

Ground Pin(Case Ground)

Electrolyte

Cell Cup BottomT.P. Insulator

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Fuze batteries used lead/fluoboric acid/lead dioxide system from early 1960s until late 90s• At one time, industrial base included EaglePicher, Eveready, Accudyne• Army managed highly-specialized GOCO platers at the manu. facilities• One by one, largely for business reasons, manufactures exited the business, the

platers were dismantled, and we lost the capability to produce these batteries

In the early 90s, the Government instituted acquisition reform and the Army reorganized its laboratory system

• The Army greatly reduced its organic capability in the area of fuze batteries• The R&D burden was left almost entirely to the commercial sector

Mitigating these events was the emergence of lithium-based battery systems in the mid-80s, and the existence of ATK-Horsham, PA as a supplier

• ATK began working on multi-cell lithium-based reserve batteries in the mid-80s, at times with ARL participation

• In the early 90s, ATK began development of the first such fuze battery, the MOFA (Multi-Option Fuze for Artillery), which was produced from 2002-2007

Timeline: 1960s-Present

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Navy’s MFF (Multi-Function Fuze) battery development• Beginning around 1999, the Navy made two attempts to modify the MOFA battery design

to meet the requirements of the MFF fuze• Higher voltage and greater current draw (added cells but had a fixed electrode area)• Full power required much earlier in MFF than MOFA

• Neither attempt was fully successful; primary issue was rise time

Submunitions and medium-caliber (25-40 mm projectile) applications• Beginning in the late 1990s, efforts began to add electronic fuzing to a number of new

applications that would require much smaller batteries• eSDF, OICW, XM80, ANLM, LW30, SAGM

• Most of the new applications included a proximity function, requiring 10s of mA• Medium-caliber applications are typically short mission lives, but require very fast rise

times (100-200 ms)• Success has been hard to come by

• The batteries need to be really small• Programs come and go, making it hard to gain traction• Nature of the electrochemistry extremely limits materials of construction• Cold temperature rise time continues to be an issue

• But, efforts persist, because we want the capability

Challenges Emerge

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The industrial base for fuze batteries is very small• EnerSys has been the only committed producer for the last 20 years

The Army has not had a fuze battery in high-rate production since 2007• Financial stress on the existing base• No incentive to expand base• Harder to argue for significant R&D investment

Organic Government capability remains very limited

DoD-unique; no opportunities to leverage commercial activities

The Government community has investigated alternative technologies• 1995 report by NSWC-Carderock (focused on large-caliber solutions)• 2002 report by Rensselaer Polytechnic Institute (ARDEC-commissioned)

The fuze community has also considered alternative electrochemical systems in reserve configuration, as well as primary and secondary batteries

Where Things Stand

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NSWCSpringTurbine alternatorFlywheel generatorGear train (runaway)Gear train (escapement)Setback generatorPiezo-stressPiezo-crushFluidic generatorThermoelectric converterGas generatorThermo-photovoltaic converterThermionic converterDriven mainspring/generatorPhotoemissive converterFerroelectric converterMagnetohydrodynamic converterRefrigerated thermoelectric converterNegator spring motor generator

Alternatives Considered

RPISupercapacitorsMicro power generation (MEMS)ThermoelectricsPhotovoltaicsPiezoelectricsRadio isotope batteriesFuel cellsSuperconducting magnetsThermophotovoltaicsConformal systems

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Going Forward, Near Term

Ongoing fuze programs will continue to pursue lithium-based reserve batteries, expanding the design and performance envelopes incrementally

ARDEC beginning aging study of select primary and secondary COTS batteries

May investigate reserve configurations with alternative electrochemical systems, at least for certain applications (i.e., fast rise time vs. higher energy density), resources permitting