Aircraft

Boeing outlines additional safety features for 787 batteries

Boeing outlines additional saf...
Boeing is confident that the redesign of the lithium-ion batteries and added safety tests will fix the safety issue
Boeing is confident that the redesign of the lithium-ion batteries and added safety tests will fix the safety issue
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787 batteries
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787 batteries
Boeing is confident that the redesign of the lithium-ion batteries and added safety tests will fix the safety issue
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Boeing is confident that the redesign of the lithium-ion batteries and added safety tests will fix the safety issue
787 battery features
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787 battery features
787 battery basic consrtuction
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787 battery basic consrtuction
Conventional electric/pneumatic system
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Conventional electric/pneumatic system
787 electric system for lithium batteries
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787 electric system for lithium batteries
787 battery showing modifications
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787 battery showing modifications

Boeing has announced improvements to the lithium-ion batteries for its 787 Dreamliner. A series of modifications to the batteries and their casings were made in response to battery fires in mid-January aboard two 787s in Boston and over Japan that resulted in all 50 of the planes delivered to customers being grounded. According to a company press release, the modifications along with improved testing regimes should prevent a repeat of the incidents.

The lithium-ion batteries have been a sensitive spot for Boeing because of the cloud that it cast over the new 787 Dreamliner. Exactly what caused the fires is still undetermined, but Boeing is confident that the redesign of the lithium-ion batteries and added safety tests will fix all the possible causes that Boeing and aircraft safety experts identified. If the modifications pass evaluation by the U.S. Federal Aviation Administration (FAA) and other international regulators, the 787 may return to service within a few weeks.

Lithium-ion batteries are part of Boeing's plans to move away from conventional onboard power systems that rely on a mixture of auxiliary power units and pneumatics to one where more electricity is used. The idea is to create a system that is lighter, cleaner and simpler by replacing pneumatic units and piping with electrical versions and wiring.

This approach requires using lithium-ion batteries due to their high amperage, low weight and fast recharge times. Unfortunately, the same heating problems that have plagued such batteries in laptops and electric cars can also effect aircraft – which is where the series of proposed changes come in.

"Our first lines of improvements, the manufacturing tests and operations improvements, significantly reduce the likelihood of a battery failure," said Mike Sinnett, vice president and chief project engineer, 787 program, Boeing Commercial Airplanes. "The second line of improvements, changes to the battery, helps stop an event and minimize the effect of a failure within the battery if it does occur. And the third line of improvements, the addition of the new enclosure, isolates the battery so that even if all the cells vent, there is no fire in the enclosure and there is no significant impact to the airplane."

Battery manufacturing now includes four new or revised tests for screening batteries, bringing the total number of tests to ten over a fourteen-day period with discharge rates being measured on an hourly basis.

As to the batteries themselves, design changes include two new insulation layers including one of phenolic glass laminate. An electrical insulator is wrapped around each battery cell to electrically isolate them from one another and the battery case and there’s more electrical and thermal insulation on top, below and between the cells to isolate them in the event of overheating. Wire sleeving and the wiring inside the battery have been upgraded to make them more heat and chafing resistant. New locking fasteners have been added to the bars connecting the cells.

787 battery showing modifications
787 battery showing modifications

The case for the battery has also been redesigned to keep the batteries away from other electrical equipment. It has a stainless steel enclosure held in place by titanium fixtures and there are vents in the case to allow moisture to drain from the bottom and to vent gases overboard while preventing oxygen from getting to the batteries to support combustion. The enclosure can withstand the failure of eight battery cells and forces one and a half times greater than any projected failure. Under tests, it withstood three times the force.

787 batteries
787 batteries

"We put this new design through a rigorous set of tests. We tried to find a way to introduce a fire in the containment but it just wouldn't happen. Even when we introduced a flammable gas in the presence of an ignition source, the absence of oxygen meant there was no fire," says Sinnett.

These steps to improve battery safety have not come without a cost. The modifications have added 150 pounds (68 kg) more weight to the 787, which negates part of the reason for using lithium-ion batteries in the first place.

Source: Boeing

14 comments
Robert Walther
Since I cannot do exponential exponents in my head, I had to use a calculator to figure that 150lbs is of a loaded 787. This disastrous weight gain will invalidate the entire Boeing air fleet. Now that a 787 can only fly 8997.3+/- miles of a planned 9000 mile journey, I recommend not only the immediate bankruptcy and foreclosure of all Boeing facilities, but also the total elimination of all air travel anywhere on the planet. The 787 is a ridiculous aircraft. The rate at which the 787s fall unpredictably from the sky requires that a man, possibly a freelance playwright, should walk beneath the 787 waving a red flag to warn pedestrians of imminent falling sky, chicken optional.
James Poch
"the same heating problems that have plagued such batteries in laptops and electric cars can also effect aircraft". Electric cars have not been plagued with anything other than the mishandling of crashed equipment. Of the 70,000 OEM electric vehicles on the road, I am not aware of any fires taking place while on the road. The only incident that I am aware is when testers at the NHTSA forgot to discharge the batteries of damaged Chevy Volts. In storage, days or weeks later, the damaged Chevy Volts caught fire because the batteries weren't discharged much like they emptied gas tanks prior to storage. This mishandling is hardly a problem that can be replicated in a real world scenario. Unless, someone is trapped in a car for two weeks but my guess is they will die of dehydration before damaged batteries catch on fire.
BeWalt
@ rgwalther: Gee dude - who, or what, pushed your button? Calm down :) This is a good article, largely quoting from a Boeing press release and not (at all) adding the lots of bull and hog, like you would find on superstyle Gizmodo kind of websites. Thanks for the good work, and keep it right up, David!
Slowburn
The question I have is, "What is the new weight differential between the new battery packs and the power equivalent battery packs using the old battery type?"
WagTheDog
This may suffice for awhile, but I won't trust ANY lithium battery until the chemistry has been altered to insure that overheating and fire have become non-issues. Work is progressing on this ... does anyone know it's current status?
Mel Tisdale
There is one aircraft that has an APU that is purely fan driven. It hinges down into the airstream somewhere near the tail in an emergency. That has always struck me as a sensible solution to power loss when airborne. I suppose that there are objections to it, otherwise it would be more widely used. As for the Dreamliner, I think I will wait a year or two. If by then, none have fallen out of the sky as a result of the new technology it employs having failed in some way, then I will consider flying on one. Until then, others can provide the necessary crasth test dummies.
ClubDoug
@ James Poch: You may be correct about electric cars not having had similar issues. As far as I know a lot of electric cars use Nickel Manganese Cobalt batteries which are a completely different technology altogether. @WagTheDog: Current aircraft batteries are either Lead Acid or Nickel Cadmium (NiCd). The NiCd's are more common in aircraft AFAIK. I don't know about the status of altering the lithium battery composition other than what's in this article, but NiCd's can definitely overheat and catch fire just as easily. Just Google NiCad Thermal Runaway. Trust me, I maintain and service aircraft NiCd batteries for a living! @funglestrupet: the fan driven APU is a good idea for emergencies, but you still need a normal jet powered APU for ground operations. The APU provides the power to the aircraft while on the ground before the flight, to power the lights, air-conditioning, and cockpit power to allow the pilots to do their pre-flight checks and enter their flight path into the flight management computer etc etc.
Atlantide
I've been using LiPo batteries for model planes, and I don't trust them any further than I can throw them. I hope that Boeing only understands these batteries as an interim solution until the technology is less risky (other than using "electrical insulation tape" to make everything safe). Saving on weight is one thing, risking air crew & pax's lives is another. The 787 is a beautiful design, I hope it won't have to be grounded again. P.S.: "funglestrumpet" referred to the RAT emergency power unit that pops out of the fuselage of some Airbus models in case of in-flight electrical failure, see http://de.wikipedia.org/wiki/Ram_Air_Turbine . This has already saved many lives, in conjunction with exceptional pilot skills. See http://en.wikipedia.org/wiki/Air_Transat_Flight_236 .
JAT
I'll wait a year or more before I get on one of those things.
Pecos Pete
I wonder if these batteries are pressurized to negate the different pressures at different altitudes?