Monday, February 18, 2013

Lithium Ion Batteries: Not Airworthy?

With the recent fire that grounded fleets of Boeing 787 Dreamliner passenger planes due to their auxiliary power unit batteries being a fire hazard, are lithium ion batteries not airworthy?

By: Ringo Bones

Believe it or not, the world’s first all-electric powered propeller plane that has successfully flown – Calin Gologan’s Elektra One – uses lithium ion batteries as its primary power source and there are already large-scale all-electric passenger planes intended aimed for airline company use already in the works of Bauhaus Luftfahrt that will be powered with 40-megawatt-hour lithium ion batteries. Given their allegedly inherent fire hazard, why are lithium ion batteries got airworthy credentials despite the ones supplying the auxiliary power unit of the Boeing 787 Dreamliner that entered service with JAL and ANA were recently deemed a “fire hazard” in a recent Federal Aviation Administration inquiry?

As a fruit of our continuously galloping technology, lithium ion batteries are a notch above nickel cadmium and nickel metal hydride storage batteries that are a few rungs below it on the battery technology evolutionary scale. While lead acid / lead calcium storage batteries – which might work just fine for golf carts and short-range all electric cars – are deemed too heavy for aviation use. Even the nickel cadmium and those nickel metal hydride batteries used in hybrid cars just don’t have the power-to-weight-ratio requisite for general aviation applications.

The secret of the lithium ion batteries high power-to-weight ratio is its inherently low internal resistance compared to nickel cadmium or nickel metal hydride batteries of similar watt-hour ratings. Although, at the moment, lithium ion batteries seems like the ideal battery – the inherent fire hazard of its design was first noted in the remote controlled model plane hobbyist world and in Airsoft electric gun gaming world because less than ideal charging and discharging cycles in its applications always lead to the cause of hydrogen gas build-up which can be highly inflammable when it leaks and ignited by a stray electrical spark. Given its inherent fire hazard, aircraft manufacturer Airbus are already finding alternatives of the lithium ion battery planned to be used on the auxiliary power plant of its upcoming A350 plane due to the recent battery fire on the Boeing 787 Dreamliner. Will the next generation of lithium ion batteries intended for aviation use should be made more fire resistant or have a built-in fire suppression system? 

1 comment:

  1. The Bauhaus Luftfahrt concept of an all-electric passenger plane powered via a rechargeable 40 megawatt-hour lithium-ion batteries reminds me of Word War II era submarines.