1. Donn Arnold- Krum ISD Laura de Lemos- Carrollton Farmers Branch ISD RET Project- Summer 2009 College of Engineering, Dept of Electrical Engineering University of North Texas NSF Grants: NSF IIS-0844342, DLR, 0431818, CI-TEAM 0636421, CRI 0709285 August 13, 2009

2. Will insulation of the sensor boxes help to sustain the lifespan of battery charge by maintaining battery temperatures within their optimal (manufacturer’s recommended) operating temperature ranges? Thermal Effects on Lifespan of Battery Charge When Deployed in a Wireless Sensor Network

3. Initial concern: extreme thermal effects on the wireless sensor and the lifespan of the battery’s charge After research, our primary concern became the thermal effects on the batteries themselves We decided to study the effects on the lifespan of the battery’s charge when insulation is installed in wireless sensor boxes Introduction

4. Hypothesis: By controlling the internal temperature of the boxes within manufacturer’s prescribed operating temperature range, the lifespan of the battery’s charge will be extended. During the testing of the effects of insulation, 3 types of batteries were tested: alkaline, nickel metal hydride, and lithium ion batteries. Introduction

5. Limiting factor for motes is generally the battery [1] Battery must be kept within a limited operating temperature (manufacture recommended) range so that a battery charge’s lifespan can be extended[2] Research- Battery At the lower extreme, the electrolyte will freeze [3] At the upper extreme, active chemicals may break down destroying the battery [3] In between these limits, cell performance generally improves with temperature (with an upper limit)[3]

6. Optimum performance: -20 to 54°C [4] Manufacturer recommended operating temperature: -18 to 55° C [5] For most cells, up to 75% of rated capacity at room temperature can be delivered at O° C [4] Research- Alkaline Battery

7. Battery performance still impacted by temperature within the recommended range [5] Due to how fast critical fuels, water and hydroxyl ions can move and react [5] Lower temperature limit is in part due to where the electrolyte freezes [5] Current flow stops at the freezing point High drain rates in cold environments [5] Research- Alkaline Battery

8. Optimum performance: 0 to 45° C [6] At -20° C, the battery ceases to function [7] For optimum battery life and maximum life cycle, the battery should be operated at or near room temperature (20° C) [6] Capacity of the battery decreases as current increases, especially at lower temperatures [6] Very poor low temperature discharge performance [8] Research- NiMH Battery

9. Higher temperature yields higher self discharge rate [9] Cycle Life and Temperature 30° C, cycle life reduced by 20% 40° C, cycle life reduced by 40% 45° C, cycle life reduced by 50% [7] Operation at high temperatures can: Cause cell to vent, releasing gas and possibly electrolyte through the safety vent Hasten the deterioration of the separator and other materials in the cell [6] Research- NiMH Battery

10. Also known as the lithium iron disulfide battery (LiFeS 2 ) Optimum temperature range: 20 to 40° C [10] At -20° C, the battery ceases to function [7] Lowering the discharge temperature causes a reduction of capacity and an increase in slope of discharge curve [10] Rate of voltage decrease is more rapid at colder temperatures [10] Research- Lithium Ion Battery

11. At higher temperatures, chemical deterioration may be rapid enough during discharge to cause a loss of capacity [10] Higher discharge rates with elevated temperatures can cause self-heating [11] Contains safety features: thermal switch- limits current when temperature reaches 85 to 95˚C pressure release valve- activated by excessive internal pressure [12] Research- Lithium Ion Battery

12. Related Work Arizona State University-recommended thermal insulation [13] NASA Mars rovers- efforts to maximize thermal resistance [14] Worcester Polytechnic Institute- lithium ion batteries subjected to high temperatures can explode [15] Chulsung Park at the University of California at Irvine & NEC Laboratories of America- effects of high and low temperatures on batteries [16] UNT Electrical Engineering Department- motes need to be able to survive in extreme environmental conditions [17]

13. High and low temperature extremes cause batteries to self- discharge. This reduces the current available for wireless sensor operation. To reduce these effects, we will implement a pattern of insulation of the wireless sensor boxes thus: 1 box- uninsulated (control) 1 box- polystyrene rigid foam board (pink) 1 box- foil-faced polystyrene rigid foam board (white) Boxes will be subjected to high summer temperature extremes. Problem Definition

14. Throughout all the experiments, each sensor box contained the following: Crossbow Mote: IRIS XM 2110 2.4 GHz (micro computer board) Two AA Battery Pack MDA 300 Acquisition Board Experimental Design

15. Throughout all the experiments, 4 types of sensor boxes were implemented. Experimental Design

16. 1 st Deployment 30 motes in 30 sensor boxes spaced about 10 m apart All were powered by alkaline batteries 2 boxes contained pink insulation 2 boxes contained white insulation 2 remaining boxes contained no insulation Note: the second set of three boxes allow for an experimental redundancy Data collected July 25 to July 27 1 reading every 6 minutes Experimental Design- Discovery Park

17. Experimental Design- DP 1514131211109*87*6543*21 302928272625242322212019181716* non-transparent lid, uninsulated non-transparent lid, pink insulation 1 st Deployment- All alkaline batteries transparent lid, uninsulated non-transparent lid, white insulation Our focus in this deployment were boxes #2, 8, 10, and 15. *This indicates an experimental redundancy.

18. Results- DP Time (sec) 1 st Deployment Weather conditions were cloudy and overcast greatly reducing the effect of the radiant barrier Very similar results with pink and white insulation

19. Results- DP Time (sec) 1 st Deployment Unusual results for the transparent lid, uninsulated box

20. Results- DP Time (sec) 1 st Deployment #8 retained 0.1 v less than both of the insulated boxes

21. 2 nd Deployment 21 motes in 21 sensor boxes spaced about 5 m apart 3 rows of 7 each Data collected from August 5 to August 10 1 reading every 5 minutes Experimental Design- Discovery Park

22. Sensor Box Insulation Pattern- DP *This indicates an experimental redundancy. transparent lid, uninsulated non-transparent lid, uninsulated* non-transparent lid, pink insulation* non-transparent lid, white insulation* Battery 2 nd Deployment

23. Experimental Design- DP *This indicates an experimental redundancy. 2618*1528*912*3719*1629*1013*4820*1730*1114* Alkaline BatteryNiMH BatteryLithium Ion Battery 2 nd Deployment

24. Results & Discussion Time (sec) 2 nd Deployment Alkaline All alkaline battery graphs were essentially the same.

25. Results & Discussion Time (sec) 2 nd Deployment NiMH Non-transparent & pink insulated boxes- similar graphs Box #10: greater lifespan (3.82 days)

26. Results & Discussion Time (sec) 2 nd Deployment Li Ion Pink & white insulated boxes- similar graphs Box #8: greater lifespan (3.99 days)

27. Peak internal temperature of all the nontransparent lid sensor boxes was the same Try thicker insulation in larger sensor box Foil-faced polystyrene foam insulation Difference in lifespan of NiMH batteries No effect in lifespan of alkaline batteries Shortened lifespan of lithium ion batteries Overall, the alkaline battery’s charge lifespan was the greatest of all with insulation or without Conclusions & Recommendations

28. Direct sunlight conditions Discovery Park and Water Treatment site Recommend NiMH batteries Solar panel recharge device Shaded conditions Greenbelt site Recommend alkaline batteries Lifespan is the longest Conclusions & Recommendations

29. Future Work: Winter Temperatures We did not have time to conduct a winter temperature simulation with sensors in an ice chest We would like to run an experimental design identical to deployment 2 in Discovery Park in January Extreme winter temperatures could have a greater effect on the lifespan of a battery’s voltage, as per manufacturer’s specifications

30. Dr. Murali Varanasi Dr. Oscar Garcia Dr. Miguel Garcia Rubio Dr. Miguel AcevedoJue (Jerry) Yang Dr. Xinrong LiNing (Martin) Xu Dr. Yan HuangNitya Kandukuri Dr. Shengli Fu Mitchell Horton The following people were instrumental in bringing us to UNT to conduct this research. We wish to thank them all for going far above and beyond the call of duty in assisting us with our project.

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32. [6] Procter & Gamble. Duracell: Nickel Metal Hydride: Technical Bulletin. 2009. 28 July 2009. <http://www.duracell.com/oem/rechargeable/Nickel/ nickel_metal_tech.asp>. [7]Buchmann, Isidor. Discharging at High and Low Temperatures. 2003-2005. 29 July 2009.. [8]Fetcenko, M.A., et al. “Recent advances in NiMH battery technology.” Journal of Power Sources. 165 (2007) 544-551. [9] Kopera, John J.C.. “Inside the Nickel Metal Hydride Battery.” 25 June 2004. Cobasys. 29 July 2009. <www.cobasys.com/pdf/tutorial/ inside_nimh_battery_technology.pdf>. [10] McKissock, Barbara, et al. “Guidelines on Lithium-Ion Battery Use in Space Applications.” March 2008. NASA Engineering Safety Center Battery Working Group. 30 July 2009. <http://ntrs.nasa.gov/archive/nasa/ casi.ntrs.nasa.gov/20090023862_2009023573.pdf>. Works Cited

33. [11] Buchmann, Isidor. Is lithium-ion the ideal battery?. 2003-2005. 30 July 2009.. [12] “AA Portable Power Corp: Product Specification: Lithium/Iron Disulfide.” 3 Aug. 2009. < http://www.batteryspace.com/index.asp?PageAction =VIEWPROD&ProdID=1397>. Path: 1.5V 2900mah Lithium AA. [13]Bannister, Kenneth, Gianni Giorgetti, and Sandeep K.S. Gupta. “Wireless Sensor Networking for “Hot” Applications: Effects of Temperature on Signal Strength, Data Collection and Localization.” IMPACT Lab, Arizona State University. 16 July 2009.. [14]Novak, Keith S., et al. “Mars Exploration Rover Surface Mission Flight Thermal Performance.” July 2005. Jet Propulsion Laboratory, California Institute of Technology. 31 July 2009.. Works Cited

34. [15]Capozzo, Daniel, et al. “Lithium Ion Battery Safety.” 14 Dec. 2006. Worcester Polytechnic Institute. 31 July 2009.. [16]Park, Chulsung, Kanishka Lahiri, and Anand Raghunathan. “Battery Discharge Characteristics of Wireless Sensor Nodes: An Experimental Analysis.” March 2005: 0-7803-9011-3. IEEE. University of North Texas. 3 Aug. 2009.. [17]Yang, Jue, et al. “Integration of Wireless Sensor Networks in Environmental Monitoring Cyber Infrastructure.” College of Engineering, University of North Texas. Works Cited