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?
