Lithium Ion Batteries on Aircraft

[Sunking]

Actually, in all seriousness, any extinguisher which only halts combustion and does not also cool the battery will be useless in the case of a lithium battery fire. They will just either re-ignite or melt something without actual flame. (The oxygen for initial combustion comes from within the battery, so starving the fire of oxygen does not work and halon would also not be able to interrupt the combustion internal to the battery. It would keep flame from spreading.)

As long as the electrical source is still there and connected, nothing is going to put out an electrical fire. Just like an oilwell fire pumping 2000 gallons a minutes. YOu can piss on on it all you want and the fire keeps burning.

[inetdog]

Or halon fire supression.
Never mind the EPA outlawed that wonderful product

Actually, in all seriousness, any extinguisher which only halts combustion and does not also cool the battery will be useless in the case of a lithium battery fire. They will just either re-ignite or melt something without actual flame. (The oxygen for initial combustion comes from within the battery, so starving the fire of oxygen does not work and halon would also not be able to interrupt the combustion internal to the battery. It would keep flame from spreading.)

[Naptown]

Or halon fire supression.
Never mind the EPA outlawed that wonderful product

[inetdog]

Well electrical fires are almost impossible to extinguish.

How about a battery compartment ejector?
Although it would limit where you could put them....

[Sunking]

They were approved under the conditions that, in the event of a fire, the flames would be contained and smoke/fumes vented. The venting part isn't working so well. Still a bad decision on the FAA part.
Flames on an aircraft, excluding engine combustion, should never be permitted under certain conditions.

Well electrical fires are almost impossible to extinguish.

[AzSun]

FAA Approval

They were approved under the conditions that, in the event of a fire, the flames would be contained and smoke/fumes vented. The venting part isn't working so well. Still a bad decision on the FAA part.
Flames on an aircraft, excluding engine combustion, should never be permitted under certain conditions.

[Sunking]

When dealing with critical systems, why wouldn't they use they safest, most stable chemistry when it comes to batteries. It makes sence to me to give up a few pounds in the design for added stability of a system. I just don't get it.

Well FWIW the FAA bares a lot of responsibility because they approved the batteries for use in the 787 back in 2007. They gave permission based on NASA's use of them in satellites for the 10 previous years without incident, and because they allowed Airbus 324 to use them. I am certainly not defending Boeing, but the Government shares the responsibility.

The Airbus 324 uses them for Emergency Exit Lighting and the batteries are cycled, just a maintenance charge. The 787 uses them for starting engines, Exit Lighting, and Critical Flight Systems so they are cycled every time they start an engine.

[green]

When dealing with critical systems, why wouldn't they use they safest, most stable chemistry when it comes to batteries. It makes sence to me to give up a few pounds in the design for added stability of a system. I just don't get it.

Green

[Sunking]

LFP would make sense to me for this application. Little heavier and more ability to be abused. It all comes down to the charging system and BMS.

Doubtful they would work because LFP ha squite a bit of internal resistance. That is one reason the aircraft industry NiCd and AGM to get the very high current to run the starters on jet engines in addition they do not spill. Cobalt has low internal resistance and very high energy density. That is why Laptop Manufactures prefer to use Cobalt over LFP.

[bonaire]

LFP would make sense to me for this application. Little heavier and more ability to be abused. It all comes down to the charging system and BMS.

[Sunking]

Boeing Aircraft selected Lithium Cobalt batteries because of their high energy density. Lithium Cobalt has always had problems with over heating, thus all the bad PR about Lithium batteries. They require temperature monitoring while being charged and discharged.

[AzSun]

A little off the application but... has anybody been following the grounding of the new Boeing 787 Dreamliner ? Two had fires involving LI batteries, one on the ground and one in flight. I'm no expert on these batteries but it seems like if they have a history of catching laptops and cell phones on fire, a little more thought should have gone into its selection.
From what I have read, There are two sets of these on the aircraft, one under the cockpit and one in the tail section. Each set is about the size of two car batteries.They are used for starting the APU's and were selected because they recharge quickly and are lighter than traditional nickel cadmiums. Lighter? It comes down to about 22 pounds lighter per set, or 12 pairs of jeans. Now 50 of these are grounded and all deliveries halted. Investigators have no clue why this happened. Originally they thought it was due to over voltage but later discovered one of the incidents was not. The charging unit will not give any clues because it burned up in the same compartment as the batteries. Retrofitting to traditional technologies will be expensive. While not a problem yet, I hope the aluminum wiring that was also selected for this aircraft doesn't become one some day. I seem to remember is was discontinued for use in mobile homes years ago due to fires. So let's throw it on an airplane. This will all get fixed but what an example of penny wise and pound foolish.