Electrical Power Systems Overview Inhibits Sensors Before Inhibits Shunt Regulation SCBR Regulation DC-DC Converters Solar Cells Batteries Battery Box

Electrical Power Systems Overview

Electrical Power Systems Inhibits Inhibit Strategy consists of 4 independent, verifiable inhibits to prevent powering satellite bus –Utilizing Leach DPDT magnetically latching relays –3 relays on power side, 1 on ground side –Inhibits released shortly after Nanosat-2 is released from Shuttle (T = 20 min) –Coil transient suppression scheme TBD An additional 4 independent inhibits prevent hazardous functions –Hazardous functions include Propulsion (PPTs) Intersatellite Separation Systems (Lightband) Deployables (Antennas, Booms) –Same design as above except inhibits released after shuttle lands (T  4 days)

Electrical Power Systems Inhibits

Inhibit Details Leach XL Series Solar Cell Out Battery Out Solar Cell In Battery In MSDS + MSDS -

Electrical Power Systems Sensors Before Inhibits Maxim MAX471 for solar cell current measurement –Bi-directional, high-side current sense amplifiers –Unit is not powered until inhibits are disabled by MSDS. –No possibility of passing current through device to bus US Sensor 2121 Thermistors for battery temperature measurement Solar Cells To Inhibits

Electrical Power Systems Sensors Before Inhibits Both current and voltage measurement will be passed to Dallas 1-Wire Bus –A/D Conversion through a DS2450 Quad A/D Converter –Must be powered in order to perform A/D conversion

Electrical Power Systems Shunt Regulation

Electrical Power Systems SCBR Regulation

Donated by VPT, Inc. Supply +3.3, ±5, + 15, ±15 Volts from nominally unregulated power bus Electrical Power Systems DC-DC Converters

Electrical Power Systems Solar Cells Tecstar Triple-Junction 24% Cascade cells Heritage on DS-1, MightySat, SMEX, TRACE, others Cells supplied kitted –Cover glass –Diode on each cell –Interconnects –String terminators

Electrical Power Systems Solar Cells Termination block 2.5” 1.5” 0.030” + + – – Interconnect Coverglass 93-50D Adhesive Kapton Insulator Cell CV Adhesive CF2-135 Primer CV-2289 Adhesive

Electrical Power Systems Batteries Both NiMH and NiCd chemistries being used Both cells types have Shuttle Flight Heritage Fabrication and verification testing by Symmetry Resources Extensive Shuttle safety testing previously completed by Symmetry Resources for both cells Raychem SRP200 or SRP350 over-current protection device Common battery box design

Electrical Power Systems Battery Assembly and Box 1.Cell testing completed 2.Cells are attached together with epoxy 3.Multiple US Sensor model 2121 Thermistors to be attached with epoxy to interior location 4.Raychem SRP200 or SRP350 over-current protection devices installed –works like a fuse –tripped at 2.5 A continuous draw 5.Entire assembly is wrapped in absorbent material –PIG MAT 203 (Primarily Polypropylene) –Sufficient to absorb all electrolyte leakage 6.Absorbent material is secured by shrink wrapping the entire assembly with Teflon 7.This assembly is then placed into the battery box

Electrical Power Systems Battery Assembly and Box Battery box will be constructed of Aluminum Two redundant vents covered with porous Teflon filters No pressure testing required The interior of the battery box will be coated with a TBD material –Non Conducting –Resistant to corrosive materials Actual dimensions of the box will differ for each satellite

Electrical Power Systems NiMH Battery Cell Model: Sanyo HR-4/3FAUX Shuttle Flight Heritage –EHIP (FAU series) –REBA (FAU series) –EHIP Light [pending] 1.2 V per cell Physical Characteristics (each cell): –Diameter: 18 mm –Height: 67 mm –Mass: 62 g USUSat Cell Configuration: –11 cells in series –4.5 A-Hr total storage capacity 7.8” 0.7”

Electrical Power Systems NiCd Battery Cell Models: –Sanyo CADNICA KR-1400AE –Sanyo CADNICA KR-1100AEL Shuttle Flight Heritage –Mightysat 1.2 V per cell

Electrical Power Systems NiCd Battery Physical Characteristics (KR-1100AEL): –Diameter: 14.2 mm –Height: 50.5 mm –Mass: 24 g Physical Characteristics (KR-1400AE): –Diameter: 17.0 mm –Height: 50 mm –Mass: 31 g

Electrical Power Systems NiCd Battery Dawgstar Cell Configuration: –20 CADNICA KR-1100AEL cells in series –24 A-Hr Total Storage Capacity –24 V Nominal

Electrical Power Systems NiCd Battery HokieSat Cell Configuration: –15 CADNICA KR-1400AE cells in series –21 A-Hr Total Storage Capacity –24 V Nominal

Electrical Power Systems Battery Box

Potting Material: PIG Corp. Mat 203 –Used by MightySat 1, others –Polypropylene Vents: Osmonics, Inc. CAMEO 25F –Polypropylene, PFTE Interface Port: AirBorn, Inc. connector