CONCORDE® LITHIUM-ION AIRCRAFT BATTERIES
Concorde® Battery Corporation is developing a series of Lithium-Ion batteries for aircraft applications. Concorde's® Lithium-Ion batteries utilize one of the safest chemistries available. They feature a cathode material made of lithium iron phosphate which is more stable than oxide-based cathodes. The batteries include a microprocessor-based Battery Monitoring System (BMS) to monitor individual cell activity and protect the battery from abnormal conditions.
In general, Concorde's® Lithium-Ion aircraft batteries will not be a retrofit battery due to the integration of the BMS. In order to assure safe operation the Lithium-Ion battery needs to be incorporated into the software and electronics of the aircraft system. Redundant safety systems built into the aircraft as well as into the battery are generally required to monitor and control the battery during all foreseeable conditions.
Although lithium-ion technology offers the prospect of lighter weight batteries, there are significant issues regarding the use of Lithium-Ion batteries for aircraft applications. These issues include increased safety hazards and higher cost of ownership when compared to traditional battery technology. Such issues should be given careful consideration when selecting battery technology for a given aircraft application.
Unlike Lead-Acid batteries, all Lithium-Ion batteries contain a highly flammable organic electrolyte. The electrolyte can overheat under certain conditions, resulting in the emission of smoke, toxic fumes and fire. The following safety incidents involving Lithium-Ion batteries illustrate the potential safety hazards that exist with this technology:
In September 2010, a UPS 747 cargo plane crashed and both pilots were killed. The accident was attributed to Lithium-Ion batteries in the cargo and prompted the FAA to issue a Safety Alert in October 2010.
In July 2011, an Asiana Airlines 747 cargo plane carrying 880 pounds of lithium-ion batteries crashed near South Korea, killing both pilots. This accident led the International Civil Aviation Organization to recommended new safety standards for the carriage of such batteries, even though the cause of the fire was not conclusive.
In late 2011 a Cessna Model 525C (CJ4) aircraft was severely damaged when the Lithium-Ion main battery caught on fire while connected to ground power. This incident resulted in an FAA emergency Airworthiness Directive (AD# 2011-21-51) that required removal of the Lithium-Ion batteries from the entire fleet of aircraft within 10 hours time-in-service or within 7 days from the date of the AD (10/6/2011). The Lithium-Ion batteries were replaced with Concorde® Lead-Acid batteries.
Boeing 787 Dreamliners were grounded in January 2013 following two Lithium-Ion battery incidents. First, a fire on a Japan Airlines 787 was discovered by the cleaning crew shortly after passengers and crew deplaned when smoke was detected in the cabin at Boston's Logan International Airport on January 7, 2013. On January 16, 2013 an All Nippon Airways aircraft made an emergency landing in Japan after pilots received a battery malfunction warning and a burning smell was reported from the cabin. The fleet remained grounded until April 2013 when battery fire containment solutions were put into place.
Lithium-Ion batteries rely on the use of a Battery Management System (BMS) to keep the battery cells safe under all foreseeable operating conditions. BMS circuits are not 100% reliable and component failure in the BMS can result in the aircraft being exposed to unsafe conditions.
The service life of Lithium-Ion batteries installed in aircraft has not been established. Some manufacturers have projected a service life of 5 years or more, but these projections are based on laboratory data and not actual field experience. It is well known that Lithium-Ion batteries for consumer applications (e.g. laptops, cell phones, I-pods, power drills, etc) have a limited calendar life, typically about 2-3 years. When used for aircraft applications, which is a more severe environment, the service life may be significantly less.
The cost of a Lithium-Ion battery is estimated to be 3-6 times higher compared to an equivalent size Lead-Acid battery. Given the possibility of short service life, it is hard to justify this price premium, especially with regards to replacement batteries. Additionally, large Lithium-Ion batteries must be shipped as hazardous material and this adds a considerable price premium for distributor of replacement batteries.
Concorde® has been working on Lithium-ion aircraft batteries since 2007 and continues to refine the battery designs at its West Covina facility. Concorde® is also working closely with the FAA to establish minimum operational performance standards to assure the safety of Lithium-Ion batteries. Currently, Concorde® believes the technology is too risky for release into commercial aviation applications.
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