Development of the Mechanical BatteryDept of Mechanical & Industrial Engineering, TAMUK

Faculty Mentor: Dr. Larry D Peel, P.E.Students: Javier A. Lozano, Luis Muratalla, Eli Hatfield, Gary Garcia,

Richard Rivera, Jonathan Boehm

AbstractOur project goal is to design a safe, efficient mechanical battery that stores energy in a mechanical form. The high power density battery is designed so that it can be recharged either electrically or by a hand crank. The manual recharging system will focus on provided a back-up form of power that could possibly be interfaced with exercise equipment. The materials used in this battery are non-toxic and light-weight. The energy will be stored using nonlinear fiber-reinforced elastomeric “storage elements.” These elements will provide efficient energy storage, but are also designed to prevent overcharging and battery failure.

Objectives include making the battery relatively small size, relatively light, and portable. The current dimensions of the battery are 24” x 14” x 8” and we are attempting to keep the weight under 15 pounds. The goal is to achieve an energy storing capacity of 2.1 to 8 MJ. The desired energy density of the composite elements is .177 MJ/Kg. Team tasks have included conducting research on similar projects, contacting NASA engineers for feedback and design ideas, conducting finite element analysis of several fiber/elastomer composite combinations, developing a power transmission sub-system, gearing, and a hand-crank system.

Composites Energy Storage Strip Research

Researched CompositesFiber Reinforced Composites Structural Composites

BenefitsMaterials AvailableLightweight

Housing

External Frame• Composite Skins• Epoxy Resin • Kevlar Fiber Reinforcement• Dimensions 24” x 14” x 8”• Aluminum Frame

Internal Frame• Provides mounting surface to attach

parts• Provides extra support• Provides mounting of “rollers” for the

strips to fully stretch more easily• Separates gear train from internal

parts

Load vs displacementIM7/RP 6410

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14

0 1 2 3 4 5 6 7

C/H displacement

Load

Load vs displacementIM7/RP6442

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0 1 2 3 4 5 6 7 8

C/H displacement

Load

IM7/RP6442

Peak Load at 49 lbs, Matrix Failed

Load was only recovered from 2 in.

IM7/RP6410

Peak Load at 11 lbs, Matrix Failed

Load was not recovered

Testing Data Analysis

Composite Energy Storage

Specimens Fabricated on the Filament Winder

Electrical Systems

443542 20A Permanent Magnet DC GeneratorSpeed: 5,000 rpm , 84Hertz generated at all speedsWeight: 4.2Kg (9.2lb) Dimensions : 150x150x300mm (6x6x12in). Resistance: Internal resistance 7.7ohms. Inductance: 16mH.Magnets: Two high-energy saturated C8 ceramic magnets. Brushes: Extra-long 8x14mm brush assemblies including spring, pigtail, and cap

NEMA DC Motors from McMaster-CarrDimensions : 5“x5”10.94“Horse Power: 1/3Torque (in-lbs): 11.7RPM: 1800

Gear System

Gear Train Design• 4 Composite strips attached to a gear driven

drum• Strips loaded in tension• Gears are clustered together to save space

Clustered Gear Design• Motor Gear• Engagement Gear• Intermediate Gear• Composite Strip shaft Gear• Generator Gear• Engagement arm• Engagement gear on end allows

engagement of either motor or generator• Gear Ratio Information• 2:1 Ratio from Motor to shaft• 4:1 Ratio from Shaft to Generator

Energy Conversion• Purpose:• Convert elastic potential energy to kinetic energy, to electrical

energy and vice versa• Components• Electric Motor• Generator• Clutch• Brake

Energy Data

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400

0% 20% 40% 60% 80% 100% 120%

Axial Machine Strain (%)

Ene

rgy

(J)

+/- 75 degrees FR1040+/- 60 degrees FR1040+/- 45 degrees FR1040+/- 60 degrees RP6442+/- 45 degrees RP6442

Energy Loss Data

30%

40%

50%

60%

70%

80%

90%

100%

0 4 8 12 16 20 24

Time (hrs.)

En

ergy

(J)

+/-60 RP6442

+/-60 FR1040

Solid Modeling

• Pro Engineer used for Solid modeling• Nei Nastran used to analyze model

Control System

Current Design• Separate manual switches for brake and

clutch• Manual switch for motorFuture Design • Torque sensor for composite strip shaft• Output sensor for generator• Load sensor for motor• Controller for brake• Controller for clutchEngagement Arm• Manual engagement for either generator

or motor

Conclusions / Future Work

• Battery Won’t have desired energy density.

• Best purpose for battery is when quick energy release is needed.

• Purchase New Transformer• Finish Building the system• Finish Building the frame• Install internal components• Incorporate electrical portion

• Test and Analyze Results• Attempt to Refine Design

Special Thanks

• Space Engineering Institute• NASA (Prime Grant No. NCC9-150)• Dr. Judith Jeevarajan• TEES (Project No. 32566-681C3)• Dr. Larry Peel • Mr. Dustin Grant• Texas A&M – Kingsville • TAMUK staff and faculty