With all the news about Lithium Ion batteries related to the Boeing 787 Dreamliner problems, it is no wonder that this technology is coming under close scrutiny by the FAA and aircraft manufacturers. Safety of both aircraft and passengers are the main concern, and with two incidents in January 2013 where the lithium-ion batteries in the Boeing 787 Dreamliner experienced thermal runaways one wonders whether or not these batteries are truly safe for use in aircraft.
Lithium-Ion Batteries In CarsLithium-Ion batteries are used in a number of applications including use in electric cars. But even here there seem to be some major road blocks. There have been reports of fires in the Chevy Volt from the lithium-ion battery, and this lead to a recall of the Volt by General Motors. An interesting article on 1-23-13 at www.propertycasulaty360.com titled "Investigating Automotive Battery Explosions" details some of the problems with these lithium-ion batteries in cars.
Lithium-Ion Batteries In AircraftIt turns out that there are problems with this type of battery in general aviation aircraft as well. In fact in late 2011 the FAA mandated that Cessna CJ4 operators replace their lithium-ion batteries. This was done because evidence had emerged that lithium-ion technology was not yet mature enough to insure safe use in aircraft. Gulfstream abandoned its use of lithium-ion battery technology for its G650 aircraft a year before final certification of the aircraft in September of 2012 following a thermal runaway and fire in a CJ4 battery on the ground.
Despite Evidence Boeing Sticks With Lithium-Ion BatteriesMany people are looking at the thermal runaway problem with the lithium-ion batteries in the 787, and in an article in Forbes online dated 2-6-13 Peter Cohen says:
As MIT professor, Donald Sadoway, explained to me in a January interview, the photos of the batteries suggest that such thermal runaway is practically designed into the 787 batteries. That’s because the eight notebook-sized lithium-ion batteries are packed next to each other in a sealed metal box. Those batteries are prone to heat up and the 787 battery design makes it difficult to vent that heat. Boeing told regulators that it had implemented a computer controlled system to stop such overheating. Moreover, if that system failed, Boeing’s system would channel the resulting smoke and flames outside of the aircraft without getting into the passenger cabin. Needless to say, this system did not work with the flights that prompted regulators to ground all 50 aircraft. But one thing seems to be emerging from the efforts of U.S. and Japanese investigators — thermal runaway was found on all the 787 batteries that burned up.
Laptop Lithium-Ion BatteriesIn fact there have been a number of fires with computer lithium-ion batteries, and the FAA has taken notice:
Advantages Of Lithium-Ion Batteries For AircraftHigh power lithium-ion batteries can deliver more power and a longer life for 1/2 the weight. In addition, these batteries can be recharged in a fraction of the time it takes to recharge lead acid and nickel cadmium batteries. The advantages are:
- High energy density potential for yet higher capacities;
- Does not need prolonged priming when new. One regular charge is all that's needed;
- Relatively low self-discharge - self-discharge is less than half that of nickel-based batteries;
- Low Maintenance - no periodic discharge is needed; there is no memory;
- Specialty cells can provide very high current.
- Requires protection circuit to maintain voltage and current within safe limits. Protection circuitry involves both additional hardware and software;
- On aircraft battery monitoring and alarms will be required for safe operation;
- Subject to aging, even if not in use - storage in a cool place at 40% charge reduces the aging effect;
- Transportation restrictions - shipment of larger batteries may be subject to regulatory control;
- Expensive to manufacture - about 40 percent higher in cost than nickel-cadmium;
- Not a fully mature chemistry - metals and chemicals are changing on a continuing basis;
- Extremely flammable electrolyte.