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Boeing outlines additional safety features for 787 batteries

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March 16, 2013

Boeing is confident that the redesign of the lithium-ion batteries and added safety tests ...

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 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

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

"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

About the Author
David Szondy David Szondy is a freelance writer based in Monroe, Washington. An award-winning playwright, he has contributed to Charged and iQ magazine and is the author of the website Tales of Future Past.   All articles by David Szondy
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13 Comments

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.

Robert Walther
17th March, 2013 @ 05:27 am PDT

"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.

James Poch
17th March, 2013 @ 05:05 pm PDT

@ 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!

BeWalt
17th March, 2013 @ 06:12 pm PDT

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?"

Slowburn
17th March, 2013 @ 10:51 pm PDT

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?

WagTheDog
18th March, 2013 @ 03:35 am PDT

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.

Mel Tisdale
18th March, 2013 @ 05:08 am PDT

@ 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.

ClubDoug
18th March, 2013 @ 06:56 am PDT

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 .

Atlantide
18th March, 2013 @ 07:19 am PDT

I'll wait a year or more before I get on one of those things.

JAT
18th March, 2013 @ 10:25 am PDT

I wonder if these batteries are pressurized to negate the different pressures at different altitudes?

Pecos Pete
18th March, 2013 @ 12:11 pm PDT

Hello people still with brains: if this part made outside Boeing and purchased for whichever reason is showing visibly serious problems,

pray tell: what about the others in similar conditions?

I'm telling my friends in Europe and elsewhere not to fly but to take a boat home (as long it is not a costa Cruise...)

Geraldo Franco
18th March, 2013 @ 03:10 pm PDT

This one is for 'WagTheDog'. And repeats my earlier post. Manganese and Cobalt and stuff are unstable in Lithium cells. I don't even trust my Electronic Cigarette without constant surveillance. So I ask Boeing people again:- If the Chemistry is not LiFePO4 which cannot explode and cannot catch fire then why not. There is a 10% specific capacity loss in WH/Kg but it looks like Boeing have more that made up for that with the JUNK they are surrounding their batteries with. LiFePO4 is the only chemistry used these days in electric vehicles (excluding race cars etc) because it is the only high energy density that is safe.

Pete_Morrison
19th March, 2013 @ 01:02 pm PDT

Re: Pete_Morrison

Possibly .. with a grain of salt, notably NOT a Lithium salt!

Lithium in any situation can be a dangerous element!

Think: Li + H2O -> (usually a very undesireable result!)

I own and regularly use two high-end 'Pedelectric' bicycles which use 14kwh Li batteries. Never has there been a problem, each of them is charged regularly using appropriate (i.e., 'auto shutoff at full charge') charging devices. I trust them but I respect them, too .. just as i respect a car's Pb-H2SO4 ('lead-acid') battery . Considering the $0.13 cost to travel same distance as a modern 30mpg car can go on one gallon, the economics are a no-brainer. This means that there's still tremendous 'economic room' for future design advancements to further Li battery safety, whether LiFePO4 or Li-ion (a misnomer, really.. all use ions).

For bikes, weight is the issue driving battery selection, but i dont see that as being so important for any plane the size of the 'DreamLiner' .. What will airlines do?.. push seats another 1/2" closer together to make up for the weight cost of improvements? Yeah, they will .. have no doubt!

tkj
10th April, 2013 @ 05:54 am PDT
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