The record-breaking flight from Nagoya, Japan to Kalaeloa, Hawaii by Andre’ Borschberg in Solar Impulse had more difficulties than were immediately apparent to even the most involved observer. During the first climb out of Nagoya, some of the cells mounted behind each motor experienced overheating, now attributed to over-insulation. High-density foam packed around the cells was apparently too effective for even the freezing temperatures at altitude and caused the batteries to become warmer than desired. As explained on the Solar Impulse web site, “The energy collected by the solar cells is stored in lithium polymer batteries, whose energy density is optimized to 260 [Watt-hours per kilogram]. The batteries are insulated by high-density foam and mounted in the four engine nacelles, with a system to control charging thresholds and temperature. Their total mass amounts to 633 [kilograms] (1,393 pounds), or just over a quarter of the aircraft’s all-up weight. “In order to save energy, the aircraft climbs to 8,500 meters (27,887 …
Less Expensive Batteries May Lead to More Homebuilt Electric Airplanes
It came as somewhat of a shock that high-quality lithium battery prices could drop low enough to encourage electric aircraft developers an opportunity to “scrounge” in the style of the original home-built airplane builders. Early aircraft “home-builders” often cannibalized war-surplus aircraft or wrecks of private planes for parts and materials that could be adapted into their own designs. Ground power units (GPUs), for instance, became an early supply point for engine cores that could be converted to aircraft use – possible on “Experimental” homebuilts, although frowned upon by the FAA for factory-builts. Your editor thought at one point that auto wrecking yards might provide a source of used batteries for experimental electric airplanes, but the thought of all the internal fracturing and potential for disaster with batteries of previously stable but now uncertain reliability cooled that enthusiasm. These batteries should not be used, but rather recycled. A discussion in Green Car Congress surprised with seemingly ultra-low, but verifiable prices on …