Two Battery Fires in Self-Launching Sailplanes

Dean Sigler Batteries, Sustainable Aviation Leave a Comment

Klaus Burhard publishes a wonderful news and blog site promoting ultralight sailplanes.  His German site has been the source for many blog entries by yours truly, and the latest items from Klaus are of concern to anyone involved with electric aircraft. He has reported in the last week on a disturbing incident with a UK-based HPH glass-wing 304eS/Shark FES “self-starter,” or self-launching sailplane.  The airplane is a standard-class 15 meter (49.2 feet) wingspan plane.  As seen in the video below, The FES (Front Electric Sustainer) motor on the nose swings a propeller which folds into the front contours of the sailplane when not powering the plane.  When a pilot engages power, the rotation of the motor pushes the propeller blades out into the airstream. Two battery packs engineered by FES nest in a compact area behind the pilot.  Each pack contains 28 high-power Kokam lithium-polymer batteries of 43 Amp-hours each wired in series to give 2.1 kilowatt-hours of energy.  Packs …

Bulletproof Batteries?

Dean Sigler Electric Powerplants, Sustainable Aviation Leave a Comment

Researchers announce that a “New battery technology from the University of Michigan should be able to prevent the kind of fires that grounded Boeing 787 Dreamliners in 2013.”  The use of the word “should” is instructive, since scientist usually couch such announcements in more guarded terms. Battery separator materials are usually not the glamorous part of cell development, most headlines given to electrode and electrolyte breakthroughs.  Kevlar may be a way, within batteries, of preventing a breakthrough.  Nanofibers extracted from Kevlar, that impenetrable material in bullet-proof vests, “stifles the growth of metal tendrils that can become unwanted pathways for electrical current,” according to a University of Michigan report. Separator material stands between layers of other battery materials and ideally allows the passage of ions between electrodes in the battery.  As the researchers report, “The innovation is an advanced barrier between the electrodes in a lithium-ion battery.”  The nanofiber material has openings large enough to allow transfer of ions between anode …

Yet Another Soy Battery

Dean Sigler Electric Powerplants, Sustainable Aviation Leave a Comment

The Blog recently reported on the brilliant work of twin high school students involved with the Brookhaven Institute in creating catalysts with a molybdenum-soy base (MoSoy) that could lead to inexpensive energy storage. Now we learn of efforts at Washington State University at Pullman in eastern Washington state to develop batteries with greater energy and prevent battery fires using the humble soy bean as a base material. Grant Norton, professor in the School of Mechanical and Materials Engineering, is proud of his new lab, designed to build and test lithium battery materials in commercial sizes.   “The new laboratory allows us to scale up our research to work that is commercially relevant.’’ Norton works on tin-based electrodes, among other things, while a group of researchers led by Dr. Katie Zhong, a professor in the school, shares the lab’s equipment.  She and her graduate students are investigating solid lithium battery electrolytes such as a bio-based solid electrolyte made from environmentally friendly soy …

Solid, Man! Electrolytes Go Granular

Dean Sigler Electric Powerplants, Sustainable Aviation Leave a Comment

Most liquid battery electrolytes that conduct ions between anode and cathode also carry with them a flammability problem, especially as chemists try to pack more power into smaller batteries.  Recent fires which have grounded all Boeing 787s in the world highlight the danger. The blog has noted before the dangers of overcharging lithium batteries and especially of leaving even model airplane sized packs lying about unattended during charging. Oak Ridge National Laboratory researchers claim to have demonstrated safety advantages with a nanoporous electrolyte, according to a January 23, 2013 release.  ORNL’s Chengdu Liang says, “To make a safer, lightweight battery, we need the design at the beginning to have safety in mind.  We started with a conventional material that is highly stable in a battery system – in particular one that is compatible with a lithium metal anode.” In line with objectives set by Secretary of Energy Steven Chu, using pure lithium metal as an anode could produce batteries with …