Polar Power Alaska: Page 6 of 7

severely compromised, with fully half of the cells performing well below acceptable standards. Basically, the battery bank would reach a point in the discharge cycle where it would just collapse, and voltage would plummet.

Running several deep discharge/charge cycles restored a bit of capacity, but it was clear that we would have to address the problem more comprehensively. Unfortunately, despite many prior communications on the subject, NPS was not prepared to address the battery problem to my satisfaction. Shipping out an entirely new battery bank within a few days was out of the question.

What we managed to do was to locate a single cell to replace the most severely compromised cell in the stack. We also reset the charge parameters to favor battery longevity over fuel efficiency and long-term generator performance. A major component of the field maintenance next year will be to replace the existing battery bank with a new and adequately sized stack, capable of handling the rigors of this application.

Take a Look

The renewable energy enhancements made on the Ivotuk electrical and telemetry system have dramatically increased system performance. So far, it appears that we may be able to stretch our fuel supply out to the extent that annual maintenance/fueling is achievable, even with the degraded battery bank. The replacement of the battery bank next year will definitely make a once per year visit possible. By adding renewable energy inputs, we have also enhanced the reliability of the system markedly.

Being able to see how the system is performing on a daily basis has allowed us to reach conclusions based on real data, rather than on assumptions, which has often been the case with autonomous systems in the past. This is cutting-edge technology, and there have admittedly been some painful lessons learned along the way.

I have absolutely no doubt that this system will continue to evolve, and point the way towards better, smaller, more easily deployed, and less costly systems in the future. In the interim, the Ivotuk system is on-line and doing its job, 24 hours a day, 365 days a year. Why not take a look and see how it’s doing right now? See transport.sri.com/ivotuk.

Access

Tracy Dahl , Project Manager, VECO Polar Resources, 8392 S. Continental Divide Rd. #104, Littleton, CO 80127 • 719-859-4484 • polarsolar@direcway.com • www.vecopolar.com • Also see www.polarpower.com, a Web site providing resources for the polar research community in developing energy systems to enable remote scientific research

Roy Stehle, Senior Engineer, SRI International, 333 Ravenswood Ave., Menlo Park, CA 94025 • 650-859-2552 • roy.stehle@sri.com • www.sri.com

National Science Foundation, 4201 Wilson Blvd., Arlington, VA 22230 • 703-292-5111 • Fax: 703-292-9095 • info@nsf.gov • www.nsf.gov

Northern Power Systems, 182 Mad River Park, Waitsfield, VT 05673 • 877-496-2955 or 802-496-2955 • Fax: 802-496-2953 • info@northernpower.com • www.northernpower.com • Generator module

Greg Egan, Remote Power Inc. • 888-257-3639 or 907-457-4299 • Fax: 907-457-4290 • greg@remotepowerinc.com • www.remotepowerinc.com • Wind & solar-electric system components and design

Proven Energy Ltd., Wardhead Park, Stewarton, Ayrshire, UK KA3 5LH • 44-015-60-485-570 • Fax: 44-015-60-485-580 •