Team Voltanators: Harley Ihrig Jim Kim Bonnie Levitt Gerardo Pulido Community College of Aurora COSGC Symposium April 20, 2013

 This mission is designed to determine whether lithium- polymer batteries can perform at least as well as the alkaline batteries for the duration of the BalloonSat flight.  Lithium-polymer batteries will reduce the mass needed to power the BalloonSat as well as saving money due to their ability to recharge.  Reducing the base mass of the payload will allow future students more mass for their experiments.  Simple Performance Comparison Test

1. The lithium polymer batteries attain and maintain at least as much heat as the alkaline batteries. 2. The lithium polymer batteries remain above the cutoff voltage at least as long as the alkaline batteries. 3. During the flight, the lithium polymer batteries must meet conditions 1 and 2.

Velcro closing mechanism. Bumpers for shock absorption.

Foam compartments to secure batteries, camera, and flight tube. Braided Wires for 9 volt connectors

Foamcore Channels for Secure Mounting of Digital Temperature Sensors. Braided Wires Heat shrink tubing to secure wires and to prevent shorts. Heaters with foamcore backing, secured with twist ties.

Coiled wires Heartbeat LED for verification of data writing to microSD card. Recessed switch to prevent accidental shut down. Zip ties to stabilize switches.

Comparison of Alkaline and Lipo Cost and Mass: Mass savings per battery: 28%, or 13 grams. Mass savings per 850 gram payload (assuming 4 batteries/payload): 7%, or 56 grams. Cost savings for the life of a lipo battery (assuming 300 charge cycles): 95%, or $ Cost of 1 lipo battery = Cost of 15 alkaline batteries. Lipos pay for themselves after 15 charge cycles. Dollars $1.32 $ grams 45.7 grams $ $80.85

 Box Redesign: Keep it compact (no wasted air space); use foam insulation.  Foamcore can withstand higher temperatures than foam.  Aluminum tape is conductive. Don’t short your electronics!  Allow for plenty of time to test the experiment.

 Two lipos will perform as well as three alkalines to power the heating circuit.

 Lipo batteries contain protection circuitry to prevent an overdischarge.  For the specific heating circuit used in our BalloonSat, lipos performed better than the alkalines due to their higher nominal voltage, smoother voltage discharge curve, higher energy density, lower mass, and long-term cost savings.