Why We Are Not Waiting Around for Batteries to Improve
LONG RANGE ELECTRIC FLIGHT…NOW: Consider this: on our electric superbike, we had the best of the best lithium-ion polymer prismatic pouch cells, 108 of them at a retail price tag of $40,000. On one hand, these cutting-edge cells are very impressive – able to sustain 600 amp current draws, producing a fully charged voltage of 453.6 and storing 12.4 kWh at an unpackaged weight of 200 lbs. They allowed our reasonably nimble-handling roadracing motorcycle to hold nearly three times the stored energy of a Prius (Toyota’s 2012 model has 4.4 kWh) and exceed 200 mph. But compared to gasoline’s energy density of 12,000 Wh/Kg, the 140 Wh/Kg we got out of these cells is 86 times worse. While they allowed us to captivate the world with our gasoline bike equaling performance demonstrations, we could only match the gassers for 6-7 laps (12 with our patented front wheel KERS system) around a typical racetrack. The performance matching was great, the range was terrible, and this was a no-holes-barred $250,000 motorcycle built by aerospace engineers.
Electric motors are much more efficient than their gasoline counterparts – our liquid-cooled permanent magnet DC motor produced up to 258 horsepower and was 92.5% efficient in the ranges we operated in most often – the radiators on our superbike never even got warm. Gasoline motors are 25-30% efficient, with the very best from Formula-1 racing clocking in at maybe 35% through their use of exotic materials, coatings and precision assembly. So using the 92.5% electric vs. 35% gas may be seen to adjust the energy density disparity down somewhat (batteries now 32 times worse than gas) if you want to look at the entire system efficiency / performance this way.
Advancements in battery technology are happening daily and at an impressive rate. Panasonic claims 245 Wh/Kg from their NCR18650A cell; start-ups like Envia have claimed up to 400 Wh/Kg (although only at lower power levels) and primary lithium cells (non-rechargeable, also low output amperages) can be found at 500 Wh/Kg and even higher for military use (if you don’t mind spontaneous fires and ITAR inspections, 1000 Wh/Kg is possible but not rechargeable and not suitable for vehicle use due to very low current outputs). We have ongoing discussions directly with the laboratories of top lithium-ion battery companies and they report 300 Wh/Kg is working in the lab but currently doesn’t allow enough recharge cycles to be acceptable to consumers, while densities over 400 Wh/Kg are also possible but unconscionably expensive and can only be recharged a few times. So we’re not waiting around for batteries to catch up with fossil fuels. We’re working around the issue with a creative and exciting solution that is going to change the face of aviation by making it green and exciting…and soon!