1、_SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising theref
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4、(outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.orgSAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/AIR5561AEROSPACEINFORMATION REPORT AIR5561Issued 2013-10 Lithium Battery Powered Por
5、table Electronic Devices RATIONALEThis SAE Aerospace Information Report (AIR) is prepared to bring attention to what is considered a potential shortcoming of current standards related to the usage of lithium-ion (Li-Ion) battery powered portable devices in conjunction with flight operations of busin
6、ess and commercial aircraft. There are well understood risks associated with the use of these commercial products, which are not currently covered by aerospace standards and regulations, and it is the opinion of this committee that potential users need interim guidance concerning the risks associate
7、d with potential li-ion battery failures in these devices.1. SCOPE This SAE Aerospace Information Report (AIR) is intended to cover any type of portable electronic device, powered by a rechargeable lithium battery that has application in operating the aircraft. This includes devices such as laptop c
8、omputers, electronic tablets, and electronic book-reading devices, used as Electronic Flight Bags (EFBs), and similar applications.1.1 Purpose This AIR is prepared to bring attention to what is considered a potential shortcoming of current standards related to the usage of lithium-ion (Li-Ion) batte
9、ry powered portable devices onboard aircraft. While work has been completed by other groups to develop standards for permanently installed, rechargeable lithium batteries, there is currently no aerospace standard for lithium battery powered portable electronic devices that are intended to be used in
10、 conjunction with flight operations.2. REFERENCES There are no referenced publications specified herein. 3. CURRENT PRACTICE In recent years, there has been rapid growth in the introduction of portable electronic devices, the majority of which are powered by rechargeable, lithium batteries. The reas
11、on is very simple. Rechargeable lithium batteries offer higher energy densities in substantially smaller packages, thus satisfying the growing power needs of electronics devices.Products powered by a rechargeable lithium battery permeate the lives of nearly everyone in one way or another. The range
12、of products runs from the indispensable, cell phone and laptop computer, to a variety of life sustaining and health monitoring medical devices, and everything in between.Unfortunately, some of these devices have experienced dramatic failures of the battery systems, giving rise to concerns about the
13、safety of lithium-ion battery technology. Investigations into the causes of these failures have uncovered issues with mismatched battery packs and charging devices, usually obtained from unauthorized third party vendors, and manufacturing defects related to foreign object contamination of the cells.
14、SAE INTERNATIONAL AIR5561 Page 2 of 4 Additional problems have come to light as a result of air transport related incidents, such as the February 2006 UPS in-flight fire that terminated in Philadelphia, the Jet Blue incident in February of 2007, out of JFK, and the loss of a UPS 747 and its crew in
15、Dubai in 2011. Most of the issues recorded by the FAA, resulted from mishandling, improper packaging, or in some cases, undetected manufacturing defects in the battery packs themselves, and a number are not limited to lithium-ion batteries. Attached below is a link to the events recorded by the FAA
16、in recent years. http:/www.faa.gov/about/office_org/headquarters_offices/ash/ash_programs/hazmat/aircarrier_info/media/Battery_incident_chart.pdfNot surprisingly, aerospace engineers are interested in utilizing this promising battery technology to meet the ever increasing power demands onboard aircr
17、aft. To aide in these endeavors, standards are being developed to guide in selecting the appropriate chemistry and for specifying battery systems that will meet the stringent requirements of the aviation application. One of the first of these standards, RTCA DO-311, was developed specifically for pe
18、rmanently installed rechargeable lithium battery systems. The requirements of this document were meant to cover a wide range of battery systems typically installed as main-ship batteries, emergency lighting batteries, avionics back-up batteries, satellite communication and surveillance system batter
19、ies and the like. However, this standard leaves one very significant gap in the intended qualification coverage, the qualification of battery systems powering portable electronic devices used in conjunction with flight operations onboard aircraft. Statistically speaking, portable devices utilizing r
20、echargeable lithium batteries are safe, as experienced by most users in their day-to day application of these devices. However, portable devices are subject to unintended abuse from being dropped or exposed to unfavorable environmental conditions, such as being left in a car trunk during the summer.
21、 It is also a recognized fact that one of the greatest risks for rechargeable lithium batteries is the potential for a thermal runaway of the battery pack (typically occurring during recharge). With the growing proliferation of portable electronic devices, it is no surprise that some of these have f
22、ound their way into aviation related applications. Most notably, there are now many models of Electronic Flight Bags (EFBs) developed from commercially available laptop computers. Some of these devices have been approved and in use for a number of years, and have become invaluable tools for flight c
23、rews. EFBs are classified as Class 1, Class 2, or Class 3 devices. Class 1 and 2 devices are considered portable and are not required to meet specific aviation related performance qualification testing. Class 1 and Class 2 devices fall under the purview of the FAA Flight Standards Service group. Cla
24、ss 3 devices are those that are installed in the aircraft, and are certified as part of the original Type Certificate or via a Secondary TypeCertificate. The FAA defines these devices as follows: EFB Class 1 and Class 2 systems are considered portable electronic devices and do not require a TSOA or
25、aircraft certification design approval (e.g., STC). EFB Class 1 and 2 systems require operational approval (suitability for use) from the PI/AEG.The rationale for the classifying EFB Class 1 and 2 systems as portable is that the software applications are limited to operational applications that have
26、 traditionally been supported by paper products. Because existing flight crew flight bags (filled with paper) have been considered “portable,” the electronic versions are also considered “portable.” These types of applications have been traditionally approved by the Flight Standards Service and have
27、 not required Aircraft Certification oversight.EFB Class 3 systems enable additional software applications that have traditionally had the oversight of the Aircraft Certification Service. The EFB Class 3 system is a powerful tool because it allows both operationally approved (Type A and B software a
28、pplications) and Aircraft Certification design-approved software to reside on the same platform with partitioning.The realization that the manufacturers of these EFBs have now switched from nickel-cadmium batteries to lithium-ion has given rise to safety concerns. The battery systems powering these
29、devices vary widely in manufacturing and component qualification standards, and to date, few if any of these have been qualified to aviation environmental conditions. This lack of standardization and configuration management leads to serious concerns over the proposed use of these or similar devices
30、 on the flight deck of commercial aircraft. With the added potential for users of these devices to bypass built-in safety devices, by substituting unapproved chargers or battery packs, the possibility of a serious safety event on the flight deck is dramatically increased. SAE INTERNATIONAL AIR5561 P
31、age 3 of 4 The FAA Aircraft Certification group has taken a first step toward mitigating this risk by proposing requirements that would place limitations on the electrical provisions and utilization of flight deck power receptacles. These limitations, if adopted,would require the operator to demonst
32、rate the safety of the devices battery pack to an approved standard before the device is approved for connection to the aircraft power receptacles on the flight deck. The proposal provides a list of tests that might be used to demonstrate compliance with minimum safety criteria for the utilization o
33、f lithium battery systems onboard aircraft.When considering the use of Li-Ion battery systems, as a part of a device utilized onboard an aircraft, it is extremely important to consider the intended use of the device, and where it will be located. As an example, a device with a 5Ah Li-Ion battery lik
34、ely represents an acceptable risk when utilized in the passenger compartment of a commercial airliner. However this same device utilized on the flight deck, adjacent to the pilots leg, represents a risk that could very well be catastrophic.As a point of information, the FAA recently performed a fail
35、ure test, utilizing a typical commercial laptop with a Li-Ion battery pack. The unit was installed on the flight deck of a Boeing 737, which had been significantly prepared to limit damage from the test. When the test article was forced into a thermally induced failure, the resultant smoke quickly f
36、illed the cockpit to the point that the instrument panel could not be seen. It took more than five minutes to clear the smoke at the end of the induced failure. It was apparent from this test that it would have been highly unlikely that the flight crew could safely operate the aircraft under these c
37、onditions. The report (Electronic Flight Bag Hazard Assessment) can be found under the Systems tab of the FAA webpage, at the following link. http:/www.fire.tc.faa.gov/systems.aspThough the potential user might have little influence over the choice of electro-chemistry utilized in commercially avail
38、able devices, the following chart provides a very basic comparison of the most popular Li-Ion chemistries currently on the market. This information will help in understanding some of the concerns and discussions relating to Li-Ion chemistries.NOTE: This chart does not begin to address the applicatio
39、n of these chemistries and the multiple levels of safety that must be designed into a battery system to make it suitable for aviation applications.TABLE 1 - CHEMISTRY SUMMARY TABLE CathodeMaterialSpecificEnergy, mAh/g Specific Power Safety Life CostLiNiCoAlO2(NCA)High160Excellent Fair - Good Depende
40、nt on cell design features Excellent High LiFePO4Medium130Very Good but: - low temperaturepower is not good - but may improveVery Good - In small cells - Needs to be verified in large format cells Good at room temperature,Bad at high temperature(6 months at 60 C)LowLiCoO2High150Good Challenging Reac
41、tivity of the chemistry requires significant design safety considerationsMedium High LiMn2O4Low 110Excellent Good,except in very large cellsAcceptableat room temp., poor at high tempMediumSAE INTERNATIONAL AIR5561 Page 4 of 4 There is a correlation between the specific energy of a cell and the relat
42、ive safety rating. It can be easily understood that cells with higher Specific Energy have the potential for a more vigorous reaction to unfavorable events such as unintentional overcharge, repeated over-discharge, and internal short circuits (manufacturing defects), and additional efforts may be re
43、quired to mitigate the known reactions of the chosen chemistries. While operational safety is a primary concern, comparison of the above chemistries does not take into account cell sizes, and some suppliers of LiFePO4 (Lithium-Iron-Phosphate) cells have advertised their products as “safe”. However,
44、many of these products are small, such as the 18650 or 26650 cells, and small cells exhibit better “safety” as a result of their better thermal dissipation characteristics. Other suppliers advertise safety as a function of unrestrained, prismatic (pouch) type cells, which allow electrodes to move ap
45、art to prevent serious over-reactions. However, this can also contribute to significantly lower performance and shortened battery life. The true comparison would be to test similar cells in various formats and / or assembled into full battery configurations. It is important to note that regardless o
46、f the positive electrode (cathode) material chosen, the vast majority of rechargeable lithium batteries utilize very similar carbon based negative electrodes and flammable organic solvent electrolytes. In respect to undesirable thermal events, it is the interface between the negative electrode and t
47、he electrolyte where the first stages of thermal decomposition begin. It is this decomposition that creates the rising internal pressure and thermal reactions that result in the release of copious amounts of noxious gas and/or smoke. In a typical cell it is not uncommon to experience the release of
48、10 L of gas per Ampere-Hour of cell capacity, during a significant thermal event. This potential creates a significant hazard that will require additional efforts to mitigate and should be carefully considered based upon the point of use onboard the aircraft. 4. CONCLUSIONS AND RECOMMENDATIONS While
49、 a thermal event with batteries is not a new phenomenon, one associated with rechargeable lithium batteries can be significantly more serious. Safety must be evaluated from the battery system level and include all the safeguards that are implemented to overcome any shortcomings of a specific chemistry. Aerospace engineers and designers should be cognizant of the risks outlined in this document, and seek guidance when contemplating the des
