Boeing 787 Li-Ion Meltdown - Page 1
Forum section: electronics / general

author: chicken
author_rank: Frequent Contributor
timestamp: January 18, 2013, 08:50:06 pm
content: I thought my fellow friends of electronic pron might appreciate this look inside the failed battery that grounded the Boeing 787 fleet:Source:http://seattletimes.com/html/businesstechnology/2020162310_787japanbatteryxml.html

author: SeanB
author_rank: Super Contributor
timestamp: January 18, 2013, 09:22:50 pm
content: Looks and probably smells similar to what the power supplies I worked on did when they died. CBB - Charred Beyond Belief.

author: r90s
author_rank: Regular Contributor
timestamp: January 18, 2013, 09:50:36 pm
content: Boeing Aerospace, back when they supplied everything that went on the space shuttle(I had many friends that worked there,) would not allow Li ion on board the shuttle.Well, if anyone can fix it, it will be Boeing.

author: G7PSK
author_rank: Super Contributor
timestamp: January 18, 2013, 10:45:08 pm
content: No doubt there will be a few cars do that as well especially after a collision, but that makes me wonder about the thinking of airlines and the various authorities governing air transport around the world, ban lithium batteries from airfreight and then allow whopping great big ones to be installed in the aircraft.

author: rollatorwieltje
author_rank: Unknown
timestamp: January 18, 2013, 10:53:15 pm
content: Considering how violent a lithium battery fire is, that box held up pretty well. I want one of those to store my R/C LiPo cells.I wonder what really caused it to catch fire. I just can't imagine Boeing didn't know rule 1 of dealing with lithium cells; "thou shalt not overvolt".

author: (In)Sanity
author_rank: Regular Contributor
timestamp: January 18, 2013, 11:00:27 pm
content: Ekkk, what a mess.I keep all of my LiPo packs in a fire safe. I have far too many LiOn batteries around and packs. Making me nervous..again.Jeff

author: fenclu
author_rank: Regular Contributor
timestamp: January 18, 2013, 11:08:51 pm
content: I remember polish airlines bragging about their Dreamliners being the first in Europe. WELL, maybe the was a reason for that

author: EEVblog
author_rank: Unknown
timestamp: January 18, 2013, 11:10:21 pm
content: Toasty!So, how long will it take them to get the planes back in the air I wonder?I can't see it being less than many months... unless they deem this to be a rare one-off?Dave.

author: ttp
author_rank: Regular Contributor
timestamp: January 19, 2013, 12:19:34 am
content: One answer to your question is that nowadays accountants make some design decisions, and the decisions are based on price, reliability and risk while engineers would think reliability, price and risk.

author: JoannaK
author_rank: Frequent Contributor
timestamp: January 19, 2013, 12:34:05 am
content: Quote from: EEVblog on January 18, 2013, 11:10:21 pmDramatic battery failure has allready happened twice. Both in this month (at Boston airport and Japan in-flight), and there have been only 50(or so) dreamliners delivered. These planes are only about 1 year old, so it can't be due old age either.For those who are interested..http://www.gsyuasa-lp.com/aviation-lithium-batteries

author: Bored@Work
author_rank: Super Contributor
timestamp: January 19, 2013, 12:53:39 am
content: Quote from: smashedProton on January 18, 2013, 11:28:04 pmThey can't. They need these batteries to start the engines. And the batteries are the backup for power, should the engines fail in flight. It is my understanding they are the only source of power in such a case. So they are freaking important, and it is not only the fire as such what makes people nervous, but that they are badly needed in emergencies.

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 19, 2013, 01:55:27 am
content: Why don't they use the safer LiFePO4 batteries?

author: tom66
author_rank: Super Contributor
timestamp: January 19, 2013, 02:27:09 am
content: Is the use of LiPo here to reduce weight, over conventional lead acid batteries?

author: IanB
author_rank: Super Contributor
timestamp: January 19, 2013, 02:49:04 am
content: Quote from: NiHaoMike on January 19, 2013, 01:55:27 amThe energy density is vastly less, and LiFePO4 batteries are not really any safer in the event of an electrical fault. I once momentarily stroked a wire across the terminal of a big LiFePO4 battery in an absent minded way to see what kind of a spark I would get--OMG, don't do that!The battery had such a low internal resistance that a momentary short produced instant smoke. Safety is relative, and a high power, high capacity battery of any type is not going to be pretty under fault conditions.

author: IanB
author_rank: Super Contributor
timestamp: January 19, 2013, 02:50:02 am
content: Quote from: tom66 on January 19, 2013, 02:27:09 amHave you considered the hydrogen/oxygen explosion risk of a lead acid battery on an airplane in flight?

author: tom66
author_rank: Super Contributor
timestamp: January 19, 2013, 03:16:20 am
content: Quote from: IanB on January 19, 2013, 02:50:02 amThey've been used for quite a while and I thought that Li-Ion was mostly used because they weigh less.I wonder if they considered NiMH, which is a much more stable and safer chemistry. Much reduced hazard with NiMH. Compromise of course here is poorer energy density, so more weight. But I don't know how significant that is.

author: Unknown
author_rank: Unknown
timestamp: January 19, 2013, 03:33:44 am
content: Most planes still have NiMH I believe. The drive towards lighter smaller batteries made them go for Lithium. Also there are no hydrolics in the classic sense on the boeing plane (don't quote me on that) making it lighter yet and more <harrumph> reliable.First Airbus with their exploding RR engines and wing cracks and now this one with melting batteries and fuel leaks. It seems beta testing with passengers on board is the new thing. Probably someone calculated that it would be cheaper to just pay insurance and crash a few instead of doing two years of pre-production tests.

author: ejeffrey
author_rank: Super Contributor
timestamp: January 19, 2013, 03:45:30 am
content: Quote from: Bored@Work on January 19, 2013, 12:53:39 amThey do have a ram-air turbine for emergency power in case of engine failure, so they do have backup power for the flight controls during an emergency landing. Still, the battery is pretty important.

author: SeanB
author_rank: Super Contributor
timestamp: January 19, 2013, 06:33:01 am
content: Most aircraft do not have NimH but NiCad packs, as they are a lot more reliable, handle abuse with little problems and are reliable and have well known failure modes. Only problem is to fit the same capacity would take 3 standard cell packs and be 6 times the mass. Flooded cells that only need a vent and some cooling, and a temperature sensor to tell the charge controller to let back on the charge or to adapt to the voltage of the warming pack. Most of them run at ambient pressure externally and can contain the result of internal failure, though a thicker case would not go amiss. As a plus the standard size unit can be serviced by existing support systems with no extra tooling or new equipment.The probable cause for these lithium failures I would guess is metal particle contamination introduced during manufacture from abraded metal particles from the production plant. Time frame is right for them to cause the failure.

author: Skimask
author_rank: Super Contributor
timestamp: January 19, 2013, 08:31:53 am
content: Solar panels on the top of the fuselage!

author: SeanB
author_rank: Super Contributor
timestamp: January 19, 2013, 08:48:09 am
content: Solar panels don't work well in thunderstorms where you are most likely to have an engine out due to either rain or hail. Not exactly good at night either.

author: RCMR
author_rank: Frequent Contributor
timestamp: January 19, 2013, 08:54:19 am
content: Lithium Ion/polymer batteries wouldn't be my first choice for an application where failure was likely to produce death.While they have a fabulous energy:mass/volume ratio -- they're also very poor performers in low temperatures (ie: anything below about 5 deg C) so I can't see that they're such a good choice for a craft that spends much of its working life in sub-zero temperatures.As someone else suggested, LiFePO4 chemistry would be a *much* better option and, although the energy:mass/volume ratio is lower, it's still more than good enough for aviation use and far ahead of the NiCd batteries they're presently using (which, by the way, work very well right down to sub-zero temps).You really have to wonder, given that they're prepared to use Li batteries to save just a few Kg here and there, how many other components have been whittled away to the bare minimum in the quest for the lowest weight and thus the highest performance.

author: Skimask
author_rank: Super Contributor
timestamp: January 19, 2013, 09:16:40 am
content: Quote from: SeanB on January 19, 2013, 08:48:09 amThen I guess they'll have to switch to daytime / fair weather flying only! Strictly VFR...And every passenger gets one of those those "shake" flashlights with power cords. Power goes out, everybody start shaking.

author: amyk
author_rank: Super Contributor
timestamp: January 19, 2013, 09:50:19 am
content: It's been pointed out somewhere else that one of the wires on the right side appears to have been pinched between the case and the cover and perhaps caused a short through abrasion of the insulation.

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 19, 2013, 12:12:26 pm
content: Quote from: amyk on January 19, 2013, 09:50:19 amOn that picture it certainly looks like one or 2 wires where pinched under the cover, but when you look at the other failed one in Boston there are no wires under the cover:

author: G7PSK
author_rank: Super Contributor
timestamp: January 19, 2013, 01:04:46 pm
content: They used to use NiFe batteries on aircraft as they had very good performance for the weight do they no longer use them. i know they are still made for industrial purposes.

author: Unknown
author_rank: Unknown
timestamp: January 19, 2013, 01:23:24 pm
content: And the shit flinging competition has begun ladies and gents.Boeing says it may be a manufacturing defect in the batteries which effects only one batch.Yuasa the Japanese manufacturer of the batteries says that the faults go beyond the batteries.Thales, the French manufacturer of the electrical system hasn't flung any shit yet but it is expected of them to blame some third world country. Any minute now.Source: The Japan Times Onlinehttp://www.japantimes.co.jp/text/nb20130119n2.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+japantimes+%28The+Japan+Times%3A+All+Stories%29edit:BTW Did you know that Yuasa also has a battery contract for the ISS? Fire in space must be a fun thing indeed. ?__?http://www.japantimes.co.jp/text/nb20130119n4.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+japantimes+%28The+Japan+Times%3A+All+Stories%29

author: SeanB
author_rank: Super Contributor
timestamp: January 19, 2013, 01:48:07 pm
content: ISS batteries are outside in a sealed compartment, so in case of oops they vent to vacuum. AFAIK they use a silver/silver oxide cell that has a life of millions of cycles, and is one of the few things that costs more to make than the shipping cost.

author: G7PSK
author_rank: Super Contributor
timestamp: January 19, 2013, 01:50:53 pm
content: Is that the shipping cost to the ISS or to the launch site.

author: SeanB
author_rank: Super Contributor
timestamp: January 19, 2013, 02:01:58 pm
content: Cost for launching the things on the Shuttle, they do not fit in a Proton.

author: G7PSK
author_rank: Super Contributor
timestamp: January 19, 2013, 02:28:22 pm
content: So what happens when the present batteries die, how do they get a new one up now there is no shuttle, looks like the pen pushers did not think thing through again.

author: notsob
author_rank: Frequent Contributor
timestamp: January 19, 2013, 03:06:13 pm
content: I would expect them to use the european automated vehicle or Spacex Falcon,which has completed 2 runs & is due for it's next flight around march time

author: Bored@Work
author_rank: Super Contributor
timestamp: January 19, 2013, 04:36:09 pm
content: Quote from: HAL-42b on January 19, 2013, 01:23:24 pmThey have the Soyuz as an escape pod. And I seem to remember a tweed from a current ISS crew member that they always have taped possible re-entry schedules near the hatch to the Soyuz to make sure they have them at hand should they be in a hurry.

author: Eliminateur
author_rank: Regular Contributor
timestamp: January 21, 2013, 01:12:21 pm
content: those control boards have an AWFUL lot of electronics(no tonly one but TWO stacked boards in a can that big...) from what i see to just "protect" the cells(and at least a monitoring connection to each cell terminals and most likely several thermocouples around the cells) which to me begs the question: where where the alerts?? (in all the grounding cases the crew noticed SMOKE or FIRE, but no master warning prior...)i mean if there was thermal runway(140°C) shouldn't all kinds of overtemp alarms be popping BEFORE the magic blue smoke & flame appears(and possibly charge/discharge cutout)?Or when it's going in flames and cells open(thus again triggering some *kind* of alarm due to cell V going to zero), so what's the point of having so much overengineered supervisory electronics on the cells if the failure detection is "goes up in flames and smokes"?granted i don't know how or what kind of interface those packs have with the avionics, but with that much board/components and knowing avionics and their overabundance of sensors there should be a ton of communication between avionics and those boards(with black box and stuff, there should be a lot of datalogging around)edit: oh i almost forget, all articles i've seen about "speculate" that there might be the cells... or overcharge... again, you're going to tell me that those supervisory boards don't have any kind of datalogging embedded or transmitted outside?, i call BS or coverup.....

author: ivan747
author_rank: Super Contributor
timestamp: January 21, 2013, 01:20:46 pm
content: Quote from: Bored@Work on January 19, 2013, 12:53:39 amHow do traditional aircraft get hydraulic pressure in case of complete engine failure?And doesn't this has an Auxiliary Power Unit?

author: Eliminateur
author_rank: Regular Contributor
timestamp: January 21, 2013, 01:24:25 pm
content: Quote from: ivan747 on January 21, 2013, 01:20:46 pmtraditional aircraft get that from the APU or in case the APU fails, teh air-ram turbine(which is an hydraulic pump in every plane except the 787)and yes, 787 has an APU like any airplane, but it's apu is just an electric generator instead of a air&hydraulic compressor/pump in normal airplanes.But you need to start the APU, and that's what the batteries are for, for powering up the avionics until the APU starts

author: G7PSK
author_rank: Super Contributor
timestamp: January 21, 2013, 02:28:10 pm
content: I understood that the APU drops down automatically in the event of a total power failure. Can Lithium cell burst into flames without first over heating, that would explain the lack of warning before smoke and flames appeared.

author: Eliminateur
author_rank: Regular Contributor
timestamp: January 21, 2013, 02:45:50 pm
content: Quote from: G7PSK on January 21, 2013, 02:28:10 pmdon't confuse APU with the air-ram turbine, they're different things.APU is not an emergency device per se, it's a "normal" device that sits on the tail of the plane usually(it's a small turbine in non-787 planes), you can notice that some planes have a exhaust in the tail cone that makes "no sense" as there are no engines there(excep on MCD planes), well that' the APU exhaust.the air-ram IS an emergency device only which drops in case of total power failure(including APU, if the APU works no air-ram extends)

author: ivan747
author_rank: Super Contributor
timestamp: January 21, 2013, 02:58:46 pm
content: Could the air-ram provide enough energy to start the APU?

author: SeanB
author_rank: Super Contributor
timestamp: January 21, 2013, 04:06:18 pm
content: APU supplies power when on the ground and not plugged into the ground supply ( 28VDC @8kA peak and 115VAC 400Hz @50A) so that the systems can be started. The APU is what is used to start the engines, it is a little dicey to use the main battery to do that, as it is capable of it ( absolutely, it will deliver 8kA into a load with a terminal voltage of 22V) but then the charging will need limiting to prevent overcharge. These batteries have a slight negative temperature coefficient and thus droop in voltage as they get hot. Can be fun if you have a starter generator on the turbine which is quite capable of charging at over 2kA, and a simple carbon pile regulator that lowers current as the voltage increases. Newer aircraft just limit the charge current to something the battery will accept as overcharge without issue.Batteries are often only monitored for voltage, and this is from a sensor set on the main DC battery bus. There are temperature sensors on many, but they are only going to tell you that the pack has exceeded 130C case temperature. ie it is either going to go or is actually cooking up.I do not know of these Liion packs, but I would surmise they are only monitored by the maintenance processor and are not actually connected to the main warning system aside from the case sensor ( monitoring being done on DCbus1, DCbus2, DCbusaux and Dcbusemerg for voltage only) which may not be used ( half the planes I worked on either did not have the sensor in the battery, and a socket next to the battery to plug it so the warning system would not show disconnected; while the others did not have the wiring at all.) on all of the planes.Ram air provides hydraulic power only to some flight systems, no electrics, that is done by the battery only, and will only be powering the standby artificial horizon, the standby radio and a set of emergency lights in the cabin and cockpit. All other systems are gone aside from the minimum - attitude, altitude, compass heading and basic controls. landing gear is not supplied, you have to manually pump the emergency release and pump the doors open and then drop the gear by gravity and pump it till it locks. No brake power assist or ABS either, you climb on the pedals with both feet and push hard, and hope you stop before you run out of runway or that the tyres do not blow out from the heat.Only one time that I was wishing I had a parachute when flying. But we landed and were able to walk away, and the plane was able to fly again as well.

author: Eliminateur
author_rank: Regular Contributor
timestamp: January 21, 2013, 04:22:44 pm
content: well since the 787 is so electronic and digital with everything fly-by-wire and that "boeing ethernet" and with it's reliance on electrical power for everything and looking at those huge supervisor boards i'm assuming it has a sea of sensors to monitor the batteries/buses(moreso taking into account that liion needs charge controllers and you can't simply plug them into the dc bus with a regulator and be done).anyone cares to find a 787 maintenance/operation manual?.SeanB, daaaayum, what where you flying when power went poof like that?.so if your batteries are out and you only have ram-air you're essentially flying pre-WW2?, no lights, horizons, radio, nothing?

author: Skimask
author_rank: Super Contributor
timestamp: January 21, 2013, 05:52:20 pm
content: Generally, ya, if the batteries are out and your flying off the RAT, you've got minimal everything.Maybe a few basic lights for the instrument panel, a self contained DC gyro for attitude and turn/bank, "steam gauges" (altitude, vertical velocity, airspeed), maybe a low wattage VHF radio for 121.5Mhz comm's, but that's about it.Then again, that's all your really NEED to keep an airplane flying.I always said the only thing I want when I'm flying is an oil pressure gauge.I can see how high up I am, judge how fast I'm going, know how much fuel is likely left in the tanks (assuming I started with full tanks), can hear the engine rpms, and can put down on practically any half decent gravel road. The only thing I can't see, hear, feel, smell is the oil pressure. And by the time I "smell", "hear", "see" or "feel" something wrong with the oil pressure, it's too late and I'm gonna land whether I like it or not!

author: jerry507
author_rank: Regular Contributor
timestamp: January 21, 2013, 06:13:18 pm
content: The ram air turbine will definitely need to be more than a few lights and a gyro on the 787. It would need to supply electrical power for the hydraulic and pneumatic systems.

author: SeanB
author_rank: Super Contributor
timestamp: January 21, 2013, 06:23:09 pm
content: Rliminateur, I was catching the bus to work..........C47 Dekota, normally a 3 hour flight with one stop then mine. 7AM departure went ok, took off, climbed to 15000 and went north along the road to the first stop. Come there and when the pilots selected gear down had from 3 blank to 3 red then 2 green one red. Tried a few times while doing circles around the runway seeing if the fault was air bubbles, but no go. Then looked out the front door ( me and the flight engineer both, leaning out under and looking, him much further out with my arm through his overall belt and the other around the seat stanchion, me calling out to the pilot the results) and we were pretty sure after looking it was an indication fault......Best landing ever in a Dakota though, smooth and so gentle, though rather perturbing in having a 45 ton Pathfinder fire engine racing down the rough next to us with a foam cannon aimed and pumps running, along with a set of hoses laid out on top. Landed, parked and checked the switch, which was faulty, then gotback in and took off to go to my workplace. Landed and walked in just at closing time...... Was asked why so late told them the Flossie broke down and we had to push it to LT.Still got a photo of that plane in an album ( film and paper) in a drawer.

author: SoftwareSamurai
author_rank: Regular Contributor
timestamp: January 21, 2013, 06:29:58 pm
content: Apparentlyit's not due to over-charging/over-voltage. So what else would cause a LiPo battery to burst into flames? Too much current perhaps?

author: Unknown
author_rank: Unknown
timestamp: January 21, 2013, 06:37:42 pm
content: GS Yuasa lithium-ion losses look to growFor GSYuasa Corp., winning the deal to supplyBoeing Co. offered the chance to make its first profit from selling lithium-ion batteries. The recent grounding of the 787 fleet on concerns about battery safety, however, means the company's losses on the technology will probably widen.GS Yuasa's multiyear, multimillion dollar contract, announced in June 2005,to supply batteries to Thales SA for the electrical system of the 787was an opportunity to offset losses from sales to carmakers. While GS Yuasa announced in 2009 that lithium-ion batteries for vehicles will become a core business, it hasn't been able to turn the technology into profit.[...]All four plants where GS Yuasa builds lithium-ion batteries are in Japan and the batteries supplied to the Dreamliners are made at a factory at its Kyoto headquarters. The electrical system, which the battery is embedded into, is manufactured by Thales, Europe's biggest defense-electronics maker.Boeing chose lithium-ion batteries for the 787 because they hold more energy and can be quickly recharged.Boeing got permission from regulators to use lithium-ion batteries in the jetliner in 2007, three years after U.S. passenger planes were barred from carrying nonrechargeable types as cargo because of their flammability.[...]full texthttp://www.japantimes.co.jp/text/nb20130122n2.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+japantimes+%28The+Japan+Times%3A+All+Stories%29

author: SeanB
author_rank: Super Contributor
timestamp: January 21, 2013, 06:42:46 pm
content: I would guess the same as what made so many laptop batteries flame, metal contaminants in the cell which eventually made it short....-24.371211,31.039365

author: Eliminateur
author_rank: Regular Contributor
timestamp: January 21, 2013, 06:44:05 pm
content: Quote from: SoftwareSamurai on January 21, 2013, 06:29:58 pmtoo much current IS overcharging.if it wasn't OV/OC, then it's either shoddy construction or the cells fail under the atmospheric conditions in the plane....

author: Neilm
author_rank: Super Contributor
timestamp: January 21, 2013, 06:56:37 pm
content: Charging if the battery is too cold can cause lithium metal to coat the electrode. This will reduce the internal cell clearances and can cause a short circuit, leading to fire.At least, that is what I got told by a rep who wanted me to use some very expensive cells in my last project as there was a requirement to charge below freezing. The must have requirement was dropped when they found out how much it would cost.Neil

author: Skimask
author_rank: Super Contributor
timestamp: January 21, 2013, 08:01:39 pm
content: Quote from: jerry507 on January 21, 2013, 06:13:18 pmDidn't say it was gonna be asmallRAT.Ya, probably have to have enough juice to at least run the trim tabs, which I would think would be just barely enough to maintain control, a couple of fuel pumps to keep the mains full for gravity feed, the gear, probably a one time blown down off a bottle, and the list goes on..and on..and on.....

author: SeanB
author_rank: Super Contributor
timestamp: January 21, 2013, 08:34:37 pm
content: RAT is a last resort, we have run out of fuel and have nothing left to keep this hunk o junk in the air device. It just allows you to turn and glide, hopefully to a landing that is a little better than a controlled crash. Remember it stops running as you come in to land, as the airspeed drops. No power just when you need some big control inputs.Basically if it deploys you are so far up shyte creek without a paddle that you better have made a will. You are just going to dig a hole and leave it for somebody to fill.

author: Skimask
author_rank: Super Contributor
timestamp: January 21, 2013, 08:52:27 pm
content: Never ran out of fuel, but I did shear both mags shafts on climbout at 2500ft AGL. The only thing the engine was good for was keeping the C.G. in limits

author: Wytnucls
author_rank: Super Contributor
timestamp: January 21, 2013, 09:01:43 pm
content: Here is the basic electrical configuration on the B787:Some very unusual voltages in aviation: for instance, +/-270VDC to run some big motors that replaced legacy systems.230VAC generators, instead of more conventional 115VAC.No constant speed drives on the generators. The frequency is allowed to fluctuate with engine rotational speed.The hydraulic system pressure is also unusually high at 5000PSI, instead of 3000PSI, to reduce the size and weight of the components. The A380 also uses a high pressure system.I just noticed that the Blue Distribution bus should have been marked as 115VAC instead of 115VDC.

author: Skimask
author_rank: Super Contributor
timestamp: January 21, 2013, 11:19:19 pm
content: 270VDC...I've seen that before...somewhere. (I used to work B-52's, C-135's, C-130's, and other large aircraft, but never saw a 270VDC bus)3 phase 400VAC from the generators, rectified, x .7071 = ~282VDC. Knock off a bit for diode drops, ripple, etc, and 270 doesn't sound too far out there.

author: IanB
author_rank: Super Contributor
timestamp: January 21, 2013, 11:33:47 pm
content: Once when I was sitting on the flight deck of a 747 and looking at the flight engineer's panel I seem to recall the total in-flight electrical load was surprisingly large, like 100's of kW or perhaps megawatts. This would have been for hydraulic pumps, HVAC systems, lighting, electronics, galley systems, avionics, fuel pumps and all sorts of things I can't recall. It surprises me that generation at 240 VAC or 400 VAC would be sufficient to handle this. I can't recall what the voltages on the the 747 were, but surely higher voltages would lead to thinner wires and lighter weight, or does that have to be offset with the additional weight of transformers?

author: tom66
author_rank: Super Contributor
timestamp: January 22, 2013, 12:28:03 am
content: I didn't know weight was that crucial (given the thing ways 110,000 kg unloaded, a ~1000 kg saving for lighter batteries and lighter systems doesn't seem like much), but I guess wherever you can reduce weight, fuel use and range can be increased.A little research says the 747-400 has 4 x 70kVA generators, those probably provide 115VAC. One per engine, and it's supposed to be able to keep level with all criticial systems functioning, on just one engine.

author: r90s
author_rank: Regular Contributor
timestamp: January 22, 2013, 10:33:12 pm
content: Dreamliner sparks doubt...http://washingtonexaminer.com/dreamliner-fires-spark-new-doubts-about-a-green-energy-technology/article/2519353#.UP7S3jXCz8C

author: tom66
author_rank: Super Contributor
timestamp: January 22, 2013, 11:18:25 pm
content: What a load of bollocks.Whilst lithium ion batteries can burn and flame, and are extremely volatile, many things on an aircraft are. For example, 33,500 gallons of jet fuel is quite flammable. A well designed battery pack will not cause a hazardous condition if it fails. It appears this happened, and the battery pack simply destroyed itself internally, with limited external carnage.An electric vehicle battery can also start a fire, but so can gasoline. There's certainly a risk with lithium ion batteries, but understanding them is important, instead of just ruling them out because of a small hazard.

author: r90s
author_rank: Regular Contributor
timestamp: January 22, 2013, 11:27:26 pm
content: Like I said earlier, Boeing Aerospace would not let Li Ion on the space shuttle, they were not allowed for safety reasons. I have been in their lab many times, about one mile away from the Johnson Space Center..have a nice rant...err...dayP.S. I also said that if anyone can make it work it will be Boeing..

author: EEVblog
author_rank: Unknown
timestamp: January 22, 2013, 11:32:07 pm
content: Quote from: SoftwareSamurai on January 21, 2013, 06:29:58 pmWhen you combine advanced technology Lithium Ion cells with huge operating temperature and pressure variations and cycling, some are bound to fail, even if used within design specs.Dave.

author: JoannaK
author_rank: Frequent Contributor
timestamp: January 22, 2013, 11:51:31 pm
content: I have no idea how many those batteries are at one Jumbo, but I'd expect there to be more than one. But whatever the estimated failure rate of these batteries are, there should be a maintenance protocol and schedule to check/replace those before they do melt down while at fly.Otoh, I have no idea if the Li-Ion destruction is known in a way that they can measure the degradation and make any good estimate about the likelihood of one battery pack going bad.

author: SoftwareSamurai
author_rank: Regular Contributor
timestamp: January 23, 2013, 02:28:17 am
content: Quote from: EEVblog on January 22, 2013, 11:32:07 pmApparently so..."In addition, battery experts have questioned whether enough testing was done on batteries to mimic the temperature and pressure of flight. The battery would essentially seek to burst open in flight if not pressurized or built for different pressure at altitude, according to battery experts."If those batteries aren't designed & manufactured to tolerate repeated large pressure changes (especially if they aren't in a pressurized compartment), I can imagine how cycle-induced stress fractures within the batteries could easily compromise their integrity and cause them to pop.

author: smashedProton
author_rank: Frequent Contributor
timestamp: January 23, 2013, 04:30:14 am
content: So the APU is the weird exhaust port on the tail that looks out of place! I have always thought that was where the poo came outI have never thought about it since I first saw them when I was six.I guess I was too busy looking at the thrust reversers. That shit is pornographic.

author: chickenHeadKnob
author_rank: Super Contributor
timestamp: January 23, 2013, 04:44:55 am
content: Quote from: smashedProton on January 23, 2013, 04:30:14 amIn case you are concerned about where your poo goes on a flight, it should go to a holding tank. Sometimes the cleanout cap to the tank can leak/come loose/fall off and then you get what aviation maintenance crew call "blue ice" for the dye that is in the water. If you ever hear news stories of mysterious blobs of ice falling from the sky, that be them. On aircraft with aft pylon engines like a DC-9 there have been blue ice ingestion events with the result of the whole engine departing the aircraft.

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 23, 2013, 04:58:50 am
content: Quote from: chickenHeadKnob on January 23, 2013, 04:44:55 amWhy don't they just discharge it just behind one of the engines, using the hot exhaust gas as an incinerator? It seems like they could save quite a bit of weight that way.

author: Eliminateur
author_rank: Regular Contributor
timestamp: January 23, 2013, 05:23:46 am
content: because that would contaminate a lot and be extremely UN-sanitary.besides the engine output is very high pressure combustion gasses, you'd need to be able to pump the liquid against that pressure needing large solid-capable pumps.... not worth it

author: Wytnucls
author_rank: Super Contributor
timestamp: January 23, 2013, 08:15:40 am
content: Quote from: EEVblog on January 22, 2013, 11:32:07 pmOn the B787, the batteries are in 2 pressurized EE compartments, which are always at the same temperature and pressure as the cabin (6-7,000 feet max).The batteries are seldom used on a modern aircraft, unless there is a drastic failure of the electrical system. The only time they are put under some stress is during APU start, if there is no external power available. Even that, seldom happens.They are always disconnected from the electrical system, except for the hot busses, which are permanently feeding a few low power vital systems. Every now and then, the batteries connect themselves to the main system to top up their charges.I would put my money on a battery flaw, possibly made worse by pressure variations and vibrations.

author: qno
author_rank: Frequent Contributor
timestamp: January 23, 2013, 11:42:01 am
content: I wonder if this could have anything to do with it.http://www.teledynereynolds.com/product/1singlepin/other/pdfs/page42.pdf

author: G7PSK
author_rank: Super Contributor
timestamp: January 23, 2013, 04:09:56 pm
content: I wonder if the seals of the batteries blew out due to reduced atmospheric pressure, I am not sure if the batteries are at cabin pressure or outside pressure, repeated cycling on the seals might cause them to blow out. As for the toilet contents at one time the tanks were emptied at altitude, some years back a large block of yellow ice landed in the garden of a London resident who lived under the Heathrow flight path.

author: SoftwareSamurai
author_rank: Regular Contributor
timestamp: January 25, 2013, 06:54:04 pm
content: Update: According to the NTSB, at least one that caught fire was due to aninternal short and thermal runaway. So, perhaps a manufacturing/QA failure?Interestingly, these batteries arelithium cobalt oxide, which are apparently "more reactive and have poorer thermal stability" than other lithium variants.

author: IanB
author_rank: Super Contributor
timestamp: January 25, 2013, 06:56:55 pm
content: Lithium cobalt oxide is in fact the standard kind of lithium battery that you would find in your laptop battery pack or cellphone.

author: tom66
author_rank: Super Contributor
timestamp: January 25, 2013, 08:30:53 pm
content: And, with this battery charging system, the battery voltage was limited to 4.025V; which is a very low limit. A typical cell has a maximum of 4.22~4.25V.

author: ptricks
author_rank: Frequent Contributor
timestamp: January 25, 2013, 09:22:07 pm
content: I am surprised to hear Boeing having problems with the batteries. I was in the Navy as an aviation electronics tech and the APU section was the least problematic of all the parts on the planes . The APU seldom use the batteries, it just isn't done in commercial aircraft because every minute the plane sits powered down is lost income so they tend to keep them powered and ready for the next flight right away . I guess Boeing needs to install a really big crank on the front or install some 3 phase sockets on the runway !

author: TerraHertz
author_rank: Super Contributor
timestamp: January 26, 2013, 10:36:27 am
content: Anyone remember how NiCd batteries turned out to be prone to growing metal whiskers between the plates, and thus self-shorting out? One cure for such dead, unchargable NiCd D-cell batteries was to give them a half second blast of 150A AC from an arc welder. Vaporized the whiskers, and the battery could be charged again.Anyway, I don't suppose Li-ion battery technology could have some similar as-yet unrecognized problem?Especially when constantly vibrated and pressure cycled, while maintained at near full charge.I don't do RC aircraft models, but I recall from chats with someone who does that Li-ion batteries are well known to be highly prone to spontaneously bursting into flames. Not from 'overcharge', but while just sitting around with a full charge. My friend told me that because of this it's best to keep Li-ion stored with only about half charge. And to store them in a fridge when not in use.The energy density of these batteries is getting pretty high. But at least it isn't yet up there with chemical explosives. Fortunately for those planes.

author: PChi
author_rank: Frequent Contributor
timestamp: January 26, 2013, 11:33:27 am
content: The pictures of the failure are interesting. The construction of the case and the way they appear to have mounted the PCBs on pillars is crude. Though the containment of the failure looks good.I wonder if we will find out if it was a failure of the protection circuits or was a problem with the cells?A couple of years ago one day in the lab were I was working there was a very loud bang then the fire alarms went off. I didn't hang around and we had a visit from the fire brigade. The incident was caused by a cycling fanatic who had used what appeared to be genuine Yuasa cylindrical lithium Ion cells for bike lights. He didn't take much care in charging them and one exploded. The cell didn't appear to have any pressure release mechanism, the metal case just ruptured which didn't impress me.

author: SeanB
author_rank: Super Contributor
timestamp: January 26, 2013, 12:36:12 pm
content: Energy density of those batteries are more than gunpowder and many low explosives though. Only good thing is that they are not shock sensitive but release as heat and low velocity gas only.Easy test will be to take some and place them in a shake-n-bake chamber, especially ones from an aircraft already in service for a while. Then cycle it to the measured vibration levels and pressure and temperature cycle it while charging it to the flight profile. Then you can see how it fails. When the first goes the rest will be in a pre failure stage for analysis without actual failure, so you can see how they will fail.

author: r90s
author_rank: Regular Contributor
timestamp: January 26, 2013, 04:52:15 pm
content: Quote from: PChi on January 26, 2013, 11:33:27 amThe same happened at a Boeing testing lab in the late 1980's or very early 90's according to a Boeing engineer.Actually blew a hole through a wall, according to what he said.

author: IanB
author_rank: Super Contributor
timestamp: January 26, 2013, 05:24:16 pm
content: Quote from: TerraHertz on January 26, 2013, 10:36:27 amSnopes could do an article on this. I don't think there is any documented instance of a li-ion battery spontaneously bursting into flames without provocation. They are very stable if you don't prod them or mistreat them. For evidence of this, consider how many laptops there are in the world with li-ion battery packs, and look for news reports of laptops spontaneously bursting into flames. There are one or two well known cases of battery recall due to defective manufacturing but the vast majority of our laptops just sit there day after day minding their own business.The two things that upset li-ion batteries the most are mechanical damage and electrical shorts. Lithium polymer batteries in particular are very sensitive to mechanical damage and you have to be especially careful with those.The reason for storing batteries partially charged is to extend their service life. Storing them fully charged will cause internal degradation and loss of performance.

author: Neilm
author_rank: Super Contributor
timestamp: January 26, 2013, 06:32:42 pm
content: Quote from: TerraHertz on January 26, 2013, 10:36:27 amLithium batteries are prone to something similar if incorrectly charged. If it has been charged at very low temperature or at too high a current (or mixture of both) then you can get lithium metal deposit building up at the terminals. If it is vibrated too much this can then damage the insulator between the layers shorting them out. This in turn leads to a hot spot that can lead to thermal run away.Neil

author: Obi_Kwiet
author_rank: Regular Contributor
timestamp: January 26, 2013, 07:34:06 pm
content: My guess is it's a manufacturing defect in the battery that would have been caught if it had been a high volume part. You can bet Boeing paid an unbelievable amount of money for each of these battery packs.It doesn't really seem like a safety issue though. For a system this big, I can thing of much worse things to go wrong.

author: TerraHertz
author_rank: Super Contributor
timestamp: January 27, 2013, 03:17:03 am
content: Quote from: Obi_Kwiet on January 26, 2013, 07:34:06 pmSo? Even if that's the case, it wasn't caught, and there's no way to be sure the problem isn't widespread among these batteries.QuoteWhat?What!?These are emergency backup batteries, catching fire on an all-composite very large airliner. How bad should it be, before it's a 'safety issue'?Edit:Quote from: PChi on January 26, 2013, 11:33:27 amWhat struck me was that the lid is just a bit of folded metal, held down with two screws per edge. There's no attempt at any kind of accident gas containment and venting to somewhere safe. There are dribbles of the vile 'stuff' down the outside of the case...The control/monitoring PCBs are in the same space as the batteries. So one battery goes, so does _everything_.The small gauge white wires (that appear to come from each battery terminal) are bundled together, and terminate in small plugs to the PCBs. Any short in these wires/plugs will place shorts across the batteries.The whole thing looks like a design by someone with the "nothing can possiblie go wrong!" mentality.

author: jerry507
author_rank: Regular Contributor
timestamp: January 27, 2013, 07:40:48 am
content: The box does seem to have contained everything to a pretty good degree though. I'm far far less concerned about the batteries failing, because it doesn't seem to have started a serious fire. What concerns me is that these batteries failing took out a large part of the avionics, and there didn't seem to be any warning that it was happening. Surprise failures are the worst kind.

author: Wytnucls
author_rank: Super Contributor
timestamp: January 27, 2013, 07:57:18 am
content: Quote from: jerry507 on January 27, 2013, 07:40:48 amI am not aware of any part of the avionics sytem failing during the ANA battery incident. Could you quote your sources please."On Wednesday, ANA's flight NH 692 left Yamaguchi Ube in western Japan at 08:10 local time (23:10 GMT) and headed for Tokyo's Haneda airport.Earlier reports that smoke was seen in the cockpit were inaccurate, ANA said. The pilots saw a warning on their computer screen telling them there was smoke inside one of the electrical compartments, the airline said. The source of the smoke is not yet known.The pilots also received a warning that there was a fault in the battery system. ANA said the battery in the forward cargo hold was the same type as the one involved in a fire on another Dreamliner at a US airport last week.The ANA flight landed at Takamatsu airport at 08:47 on Wednesday after the pilot saw an error message in the cockpit."There was a battery alert in the cockpit and there was an odd smell detected in the cockpit and cabin, and [the pilot] decided to make an emergency landing," said Osamu Shinobe, an ANA vice president, at a news conference.'

author: r90s
author_rank: Regular Contributor
timestamp: January 27, 2013, 11:25:50 pm
content: Boeing battery solution may keep 787 grounded until 2014http://news.cnet.com/8301-11386_3-57566066-76/boeing-battery-solution-may-keep-787-grounded-until-2014/Dear...Dear...

author: TerraHertz
author_rank: Super Contributor
timestamp: January 28, 2013, 08:19:29 am
content: So it's a mystery why the Li-Ion battery pack caught fire. OK, reasonable.And then, surprise.... I just now discovered this:http://shkrobius.livejournal.com/398842.htmlOn Ignorance. Aka "We don't know why Li-Ion batteries work.Bloody hell. I had just assumed someone knew, and left it at that. But apparently it's also a mystery why they work normally (when not catching fire.)Great.

author: amyk
author_rank: Super Contributor
timestamp: January 28, 2013, 08:41:09 am
content: Quote from: TerraHertz on January 28, 2013, 08:19:29 amThere have beenentire books writtenabout that, so I don't think it's fair to say "we know nothing"; better to say that we have a pretty good idea of it, and just as we don't know what exactly an electron is, it doesn't stop us from engineering electronics.

author: tom66
author_rank: Super Contributor
timestamp: January 28, 2013, 08:47:34 am
content: I'm sure they could always switch to lead acid or NiCd in the interim?

author: EEVblog
author_rank: Unknown
timestamp: January 28, 2013, 10:03:34 am
content: Quote from: Obi_Kwiet on January 26, 2013, 07:34:06 pmA fire on a plane is one of the worst things that can happen, it's a huge safety issue!Dave.

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 28, 2013, 02:08:28 pm
content: It's not the batteries?http://www.bbc.co.uk/news/business-21230940

author: Eliminateur
author_rank: Regular Contributor
timestamp: January 28, 2013, 02:13:39 pm
content: Quote from: EEVblog on January 28, 2013, 10:03:34 amsnakes on a plane is worst

author: tom66
author_rank: Super Contributor
timestamp: January 28, 2013, 03:28:08 pm
content: Quote from: BBC NewsNever heard of a li-ion battery containing any sort of fluid?!

author: IanB
author_rank: Super Contributor
timestamp: January 28, 2013, 03:32:55 pm
content: Quote from: tom66 on January 28, 2013, 03:28:08 pmThe electrolyte. In lithium ion batteries the electrolyte is a flammable organic solvent. That's why the batteries burn so nicely. Most batteries contain a water based electrolyte and don't catch fire.

author: SoftwareSamurai
author_rank: Regular Contributor
timestamp: January 28, 2013, 05:03:17 pm
content: Quote from: PA0PBZ on January 28, 2013, 02:08:28 pmOk, now I think they're just guessing.

author: TerraHertz
author_rank: Super Contributor
timestamp: January 29, 2013, 12:13:43 am
content: The heading "Airline safety inspectors have found no faults with the battery used on Boeing's 787 Dreamliner, Japan's transport ministry has said." juxtaposed with a photo of the charred mess that was the battery unit, is quite bizarre.Almost dreamlike. Dreamliner-like...Now might be a good time to buy puts on Boeing. Or perhaps too late.

author: EEVblog
author_rank: Unknown
timestamp: January 29, 2013, 01:38:12 am
content: Heaps of info and photos here:http://aviationtroubleshooting.blogspot.com.au/Dave.

author: tom66
author_rank: Super Contributor
timestamp: January 29, 2013, 01:48:00 am
content: Quote from: IanB on January 28, 2013, 03:32:55 pmWell, I've punctured a li-poly pack (not pretty... luckily I had a bucket of water nearby!) and it's just a thick kind of paste/solid stuff in there. It's certainly not liquid. I don't know if li-ion are much different.

author: IanB
author_rank: Super Contributor
timestamp: January 29, 2013, 02:24:18 am
content: Quote from: tom66 on January 29, 2013, 01:48:00 amOK, paste, but it's wet or damp and it burns very well, especially if you heat it up.In most modern batteries the liquid electrolyte is absorbed into some kind of matrix like cloth or paper or in the case of li-poly it's a kind of polymer gel. There has to be liquid in there of some kind for the ions to move and the battery to work, although the formulation is often a "starved electrolyte" kind which is bordering on the dry.

author: TerraHertz
author_rank: Super Contributor
timestamp: January 29, 2013, 07:19:31 am
content: Incidentally, for anything aircraft-related, there's always a thread somewhere athttp://www.pprune.org/rumours-news-13/(professional pilots rumor network).Currently:http://www.pprune.org/rumours-news/505455-faa-grounds-787s.htmlhttp://www.pprune.org/rumours-news/505348-ana-787-makes-emergency-landing-due-battery-fire-warning.htmlPrepare for information overload, if you enter.

author: EEVblog
author_rank: Unknown
timestamp: January 29, 2013, 08:30:56 am
content: Wow, this gives you some idea of the backups upon backups in the 787:http://boardingarea.com/blogs/viewfromthewing/2012/04/21/the-boeing-787-from-a-pilots-perspective/Dave.

author: r90s
author_rank: Regular Contributor
timestamp: January 29, 2013, 01:08:28 pm
content: Quote from: TerraHertz on January 29, 2013, 07:19:31 amI get the page, and the connection is reset right away, deleting the page!

author: phil_jp1
author_rank: Regular Contributor
timestamp: January 30, 2013, 10:39:11 am
content: Elon Musk - the founder of Tesla and SpaceX pointed out that the design itself is a complete crap. They've used 8 huge cells, that are not separated from each other in any reasonable way to prevent thermal runaway.Here's the article:http://www.flightglobal.com/news/articles/elon-musk-boeing-787-battery-fundamentally-unsafe-381627/

author: TerraHertz
author_rank: Super Contributor
timestamp: February 01, 2013, 05:46:09 am
content: http://www.flightglobal.com/news/articles/ntsb-finds-signs-of-short-circuit-thermal-runaway-in-jal-787-battery-failure-381464/NTSB finds signs of short circuit, thermal runaway in JAL 787 battery failurehttp://finance.yahoo.com/news/japanese-airlines-had-dreamliner-battery-062501475.htmlJapanese airlines had 787 battery issues before recent incidentsNeither of these articles is any kind of surprise.This all feels like watching a slo-mo trainwreck.Prediction: the 787s are never going to be permitted to fly again until Boeing has completely replaced these battery units with a new, much safer design.How long will that take? Considering Boeing was already in financial trouble due to the late delivery of the 787, this doesn't look good for them.

author: r90s
author_rank: Regular Contributor
timestamp: February 01, 2013, 03:01:22 pm
content: I don't know, but Boeing has 13,ooo,ooo,ooo sitting in the bank at the moment....

author: jerry507
author_rank: Regular Contributor
timestamp: February 01, 2013, 03:35:44 pm
content: That's a really pessimistic view. It's absolutely too early to tell if the culprit is the battery design or some other external (to the battery) factor. They'll figure it out and fix it, and hopefully redesign the battery at their leisure to a safer design.It's a 1 in a million chance that they move away from lithium ions. First, they don't have to and second, it would cost far too much money to.

author: ErikTheNorwegian
author_rank: Frequent Contributor
timestamp: February 01, 2013, 08:28:48 pm
content: Elector Elabshas started its own "The Dreamliner Project" for fixing the problem:http://www.elektor-projects.com/9130102823

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: February 01, 2013, 11:22:24 pm
content: QuoteIfanyreasonable (i.e. non-crash) external factor can make a battery do that, then the faultiswith the battery module (including its management electronics).

author: r90s
author_rank: Regular Contributor
timestamp: February 02, 2013, 12:00:19 am
content: the 787 is no DC-10http://news.cnet.com/8301-11386_3-57558639-76/when-it-comes-to-grounded-jetliners-the-787-is-no-dc-10/

author: Lawsen
author_rank: Frequent Contributor
timestamp: February 02, 2013, 02:37:10 am
content: Elon Musk, the founder of Pay Pay, Space X, and Tesla Motors, have an opinion about the spacing between LiCoOxide cell spacing for cooling:http://www.dailytech.com/article.aspx?newsid=29781

author: Obi_Kwiet
author_rank: Regular Contributor
timestamp: February 02, 2013, 02:48:01 am
content: Quote from: TerraHertz on February 01, 2013, 05:46:09 amA battery pack like this is peanuts compared to the image loss. I would guess that they are having a firm doing an expedited redesign on this and will be replacing them all at shortly. There's too much money at sake for such a trivial part.

author: EEVblog
author_rank: Unknown
timestamp: February 02, 2013, 04:54:54 am
content: Quote from: Obi_Kwiet on February 02, 2013, 02:48:01 amThey might have 2 or 3 companies working on it. Whoever delivers and passes certification first, wins. They could afford to spend $1M a day on this...Dave.

author: JoeyP
author_rank: Frequent Contributor
timestamp: February 02, 2013, 07:18:46 am
content: I have no doubt that Boeing is working at lighting speed to solve the problem. But unfortunately, once they solve it, getting FAA certification for the changes will be more like wading through a tar pit.

author: BravoV
author_rank: Super Contributor
timestamp: February 02, 2013, 07:46:53 am
content: Quote from: Obi_Kwiet on February 02, 2013, 02:48:01 amImage loss, late delivery (probably with penalty/fine), canceled orders/purchases, high chance of losing to competitor while in beauty contest period, large unknown potential cost overhead ... etc. Big headache.For sure fellows at Airbus are smiling a lot lately at work, especially the marketing team.

author: r90s
author_rank: Regular Contributor
timestamp: February 02, 2013, 11:21:20 am
content: for sure fellows at Airbus are smiling a lot lately at work, especially the marketing team.Yes, and it seems Airbus has turned off the automated fly into the ground function for now.

author: TerraHertz
author_rank: Super Contributor
timestamp: February 02, 2013, 12:30:56 pm
content: Quote from: EEVblog on February 02, 2013, 04:54:54 amQuestion is, have they created a set of design constraints that intrinsically has no safe solution?Whatever replaces the existing packs will have to fit in the same space. I recall seeing a photo of where one of the packs sit, and there doesn't appear to be much free space around it.If Boeing asked for a pack that could deliver X amount of Amp-hours at a given current, they presumably actually needed that, for aircraft functional reasons.What if there's no safe way, using any existing battery technology, to pack that much energy into the available space?E Musk pointed out that lithium battery systems *must* have sufficient space and thermal insulation between the individual cells, so there can't be a failure cascade.It looks to me like that extra space maybe isn't available in the Boeing design criteria.Hmmm...One possible workaround might be to have the cells immersed in a sacrificial fluid, that would boil off around a cell that was self-immolating. Let the evaporated fluid vent via a burst diaphragm to outside the plane.But somehow I think the safety agencies wouldn't feel good about any 'solution' which admits cells are going to just unpredictably blow up now and then.

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 02, 2013, 02:22:21 pm
content: What about flat heat pipes between the cells and a small radiator on the outside of the enclosure?

author: BravoV
author_rank: Super Contributor
timestamp: February 02, 2013, 02:50:20 pm
content: Quote from: NiHaoMike on February 02, 2013, 02:22:21 pmWhat if the outside of the enclosure where it dumped the heat is not allowed to be heated or no more free space for extruded cooling fins.

author: bfritz
author_rank: Regular Contributor
timestamp: February 11, 2013, 06:36:47 pm
content: Quote from: r90s on January 18, 2013, 09:50:36 pmThis is correct in that Li-Ion was not used, but incorrect as to why. For example, the MMU's use Lithium Thionyl Chloride, which is a metallic lithium battery, and hence much more problematic should a high temperature condition occur. These cells were used because of their very high energy density, in spite of their being more problematic than other chemistries. I know this, as I discussed this choice with the NASA engineers who made the choice.

author: Unknown
author_rank: Unknown
timestamp: February 13, 2013, 09:37:22 am
content: There has been an extensive press conference by the NTSB disclosing their findings so far.CT scans of the batteries, short circuits, thermal runaway etc.

author: r90s
author_rank: Regular Contributor
timestamp: February 13, 2013, 06:30:12 pm
content: An observation by a ARS Technica poster...http://arstechnica.com/business/2013/02/investigation-reveals-cause-of-battery-fire-on-boeing-787-dreamliner/?comments=1&post=23843299#comment-23843299

author: T4P
author_rank: Super Contributor
timestamp: February 14, 2013, 06:08:56 pm
content: Quote from: tom66 on January 19, 2013, 03:16:20 amAnd then there's another problem. High internal resistance, NiMH are absolute buggers for this. As well as limited ampacity it can take a long time to charge a BIG NiMHRam Air Jets are hella tiny, they just barely generate enough power to power a modern pitcock's basic instrumentsOnce you've seen one i don't think you want to see it again, i'll bet it probably has about several 100s of watts generating power only

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 14, 2013, 06:36:12 pm
content: Quote from: T4P on February 14, 2013, 06:08:56 pmNiMH has been used in hybrid cars for over 10 years now. 10C charge and discharge rates (in the middle of the SOC range) are not uncommon. As for weight, going to NiMH would add about 200lbs total, or less than 1lb per passenger equivalent, certainly not significant enough to matter. (If it did, airlines should charge by weight!)Or they could go with LiFePO4 which would add even less weight, as in just one passenger being as skinny as Tiffany Yep (rather than being "average American" weight) would more than offset the difference!

author: jerry507
author_rank: Regular Contributor
timestamp: February 14, 2013, 08:04:16 pm
content: And yet you see hybrid cars moving towards lithium ion technologies tooLower weight is lower weight.And as I noted earlier, the ram air turbines can't be THAT tiny. Given that the entire aircraft is fly by wire, it would need to power the main hydraulic systems and enough instruments to allow control of the aircraft. Looking at the diagram posted earlier in this thread, that's 230VAC at some pretty high amperage.

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 15, 2013, 01:03:33 am
content: Quote from: jerry507 on February 14, 2013, 08:04:16 pmIt makes sense when the weight is significant compared to the total weight of the vehicle. Most Lithium batteries in cars are Lithium Iron Phosphate or Lithium Manganese as opposed to Lithium Cobalt anyways.On the 787, the batteries make up a very tiny percentage of the total weight. If that tiny bit of weight is that significant, the variances in passenger weight would be even more significant.

author: Rick Law
author_rank: Super Contributor
timestamp: February 15, 2013, 04:12:07 am
content: Quote from: ttp on January 19, 2013, 12:19:34 amHate to tell you, the "nowadays" started well over 40+ years ago. Think Ford Pinto (and others like it). The Pinto has a habit of bursting into flames after a small back-end accident. The lack of gas tank protection was one of deliberate choices (cuts) made to keep the price of the car under a dollar a pound.Ralph Nader made his name writing the book "Unsafe at any Speed" about yet another car: the Chevrolet Corvair 50+ years ago.Perhaps if we look back even as far back as the Romans, they might have said "... nowadays, the fight look so fake ..." as the gladiator bleed to death. At times, we think the past was somehow better. Perhaps we simply do not look at the good side of nowadays enough; or perhaps the past was really was better... I will leave that to you to contemplate over.

author: Bored@Work
author_rank: Super Contributor
timestamp: February 15, 2013, 05:05:12 am
content: Can't vouche for the Romans. All that's left of them here are piles of rubble and the occasional landmark.What I see in my industry is that everything has to go faster. Having a year or even two to develop something is almost becoming a luxury.

author: T4P
author_rank: Super Contributor
timestamp: February 15, 2013, 07:31:45 am
content: Quote from: NiHaoMike on February 14, 2013, 06:36:12 pmI definitely think they wanted more energy density.

author: EEVblog
author_rank: Unknown
timestamp: February 15, 2013, 09:46:31 am
content: The investigation is now looking a dendrites being the problem:http://www.reuters.com/article/2013/02/12/uk-boeing-dreamliner-battery-dendrites-idUSLNE91B00V20130212Dave.

author: EEVblog
author_rank: Unknown
timestamp: February 15, 2013, 09:47:47 am
content: Airbus gets the heebie-jeebies and ditches Lithium Ion batteries:http://www.guardian.co.uk/business/2013/feb/15/airbus-lithium-ion-batteries-dreamlinerDave.

author: G7PSK
author_rank: Super Contributor
timestamp: February 15, 2013, 11:03:02 am
content: I was wondering if rapid pressure changes that the vents could not cope with could cause the electrodes to pinch through the plate separators. Now with the information that dendrites could be involved does reduced pressure encourage or expedite dendritic growth.

author: SeanB
author_rank: Super Contributor
timestamp: February 15, 2013, 05:41:01 pm
content: Lead free solder rears it's bad side again.

author: Mr Smiley
author_rank: Frequent Contributor
timestamp: February 15, 2013, 06:14:33 pm
content: Starts off with an interesting graph showing Specific power (W/kg) against Specific Energy (Wh/kg) for different battery types, which I hadn't seen before.The paper issue that this article comes from is almost totally about the li-Ion battery issue, and how other have tried it, given up on it, or had incidents.http://www.aviationweek.com/Article.aspx?id=/article-xml/AW_02_04_2013_p20-543232.xmlSeems that Airbus are changing (back) to NiCd for the A350 (as used on the A380).http://www.bbc.co.uk/news/business-21477126Credit for the above from a post from the picklist, so i take no credit, just passing on the infoMr Smiley

author: Neilm
author_rank: Super Contributor
timestamp: February 15, 2013, 10:55:29 pm
content: Quote from: SeanB on February 15, 2013, 05:41:01 pmThe aviation industry requires high reliability. Therefore they don't allow lead free solder to be used.Neil

author: JoeyP
author_rank: Frequent Contributor
timestamp: February 15, 2013, 11:28:26 pm
content: Quote from: EEVblog on February 15, 2013, 09:47:47 amAirbus smells "marketing opportunity". Even if Boeing could completely explain the failures, and have an absolutely reliable solution, this pretty much forces them to change to a different battery chemistry. Otherwise Airbus can use it as a differentiator for their competing model until the end of time.

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: February 16, 2013, 12:03:39 am
content: Quote from: JoeyP on February 15, 2013, 11:28:26 pmMy first thoughts too.If I was in Airbus marketing I think I would be stirring the FUD pot as well.

author: mzzj
author_rank: Super Contributor
timestamp: February 16, 2013, 11:53:33 pm
content: Quote from: r90s on January 22, 2013, 11:27:26 pmOn the other hand NASA/ESA is using normal off-the-self batteries on ISS laptops. Albeit every battery lot is tested and x-rayed.

author: jerry507
author_rank: Regular Contributor
timestamp: February 17, 2013, 12:00:59 am
content: Airbus has stated they will use the lithium ion batteries when they figure out what the problems are. They're only switching because they don't want to delay delivery because of FAA uncertainty about the lithium ion batteries.They made this decision really quickly pretty late in the project, I assume the batteries are very similar. They're even saying they'll switch the batteries on the current test planes to get test flights going again ASAP (they were put on hold because of the Boeing problems).

author: SeanB
author_rank: Super Contributor
timestamp: February 17, 2013, 06:16:12 am
content: 2 standard aircraft NiCd batteries will fit in the space of the one LiIon unit, only needs a change in the bracketry, and then some attention to the charge circuitry to handle it's voltage current curves. Might have only half the capacity though, and will be heavier. Current delivery ability though will be very impressive.

author: Colfaxmingo
author_rank: Contributor
timestamp: February 18, 2013, 03:37:36 pm
content: Can't get a CR2032 coin cell in individually wrapped plastic shipped air because science reasons will make the plain burst into flames seconds after take off.Put big Frappin ass cells in a hot box under load for hours and hours.Boeing is a shit company run by bean counters that make products sold to bean counters.Airbus is no better.

author: fcb
author_rank: Super Contributor
timestamp: February 18, 2013, 03:41:35 pm
content: Looking forward to my next flight on the plane built by your aerospace company Colfaxmingo.

author: JoeyP
author_rank: Frequent Contributor
timestamp: February 18, 2013, 08:21:10 pm
content: @ColfaxmingoEven one of you might be too much

author: N2IXK
author_rank: Frequent Contributor
timestamp: February 21, 2013, 01:19:50 am
content: Japan's Transport Safety Board finds evidence of "miswiring":http://business.time.com/2013/02/20/japan-probe-finds-miswiring-of-boeing-787-battery/As usual with technical issues, details in the mainstream press are muddled to nonexistent. The JTSB report is available as a .pdf here:http://www.mlit.go.jp/jtsb/flash/JA804A_130116-130220.pdf, but only in Japanese. Anyone able to read it and give us details?

author: chicken
author_rank: Frequent Contributor
timestamp: March 16, 2013, 12:11:37 am
content: Warming up an old thread: Boeing: ‘No fire is possible’ with 787 battery fixhttp://seattletimes.com/html/businesstechnology/2020561865_787batterybriefingxml.htmlSounds a bit like a "we don't know exactly why it happened, but let's fix everything that could possibly go wrong and contain it behind an inch of steel to be really safe" solution.

author: chicken
author_rank: Frequent Contributor
timestamp: March 16, 2013, 12:28:31 am
content: An interesting snippet from the article:QuoteIs there a fire if nobody can smell it?QuoteReiterates my description above. I think you call that Murphy's Cat - if you don't look inside the box there's no way to tell whether what could go wrong went wrong or not.

author: tom66
author_rank: Super Contributor
timestamp: March 16, 2013, 12:29:38 am
content: I'm worried. Did they find what caused the original failure and solve that, or did they just make the battery more rugged against future failures due to such faults?

author: JoeyP
author_rank: Frequent Contributor
timestamp: March 16, 2013, 12:49:53 am
content: It looks like they're "shot-gunning" it because they didn't find the root cause. That is troubling. I accept that it may very well be possible to contain the fire when there's a failure, but it looks like they expect continued failures. That will keep the issue in the news and possibly doom the 787 to the same fate as the DC10. I hope they are also working on a long-term design change which eliminates that battery chemistry altogether.

author: ee851
author_rank: Regular Contributor
timestamp: March 16, 2013, 03:38:42 pm
content: Quote from: Bored@Work on February 15, 2013, 05:05:12 amNot so. Roman aqueducts still stand, and still work. Roman arches still stand. Architecture in the USA and throughout Europe is largely based on Roman engineering. For example, the Cathedral of Learning at the University of Pittsburgh in Pittsburgh, PA is a replica of a gothic cathedral like the basilica. Examples too numerous to mention have been built overcenturiessince the Roman empire fell -- throughout Europe and the New World--basically all copies of Roman structures.Even though the Roman Empire predated the Renaissance, technologies invented by Roman engineers made the modern city possible. The Roman Empire was a powerhouse of engineering, then, as now, first to wage war against foreign armies, then to make comfortable and durable cities.The only reason the Roman water system isn't used today is that it used lead pipes, and lead wasn't found to be poisonous until the twentieth century. Most other modern infrastructural engineering marvels--highways, arched bridges, vaulted cathedrals, canal systems, city sewage, NYC water supply, shipbuilding yards, docks, etc., are based on technologies used by the Roman Empire. For example, Roman engineers invented concrete.The only manmade structures that still exist on this planet which are older than works of Roman architecture are the Egyptian pyramids.

author: grumpydoc
author_rank: Super Contributor
timestamp: March 16, 2013, 03:47:54 pm
content: QuoteUmm, Stonehenge, probably some of the Mayan and Greek temples and the megalithic temples on Malta spring to mind as man-made structures which pre-date the Romans but which aren't Egyptian. I'm sure there are others. Admittedly in Europe Roman structure vastly outnumber other ancient buildings.

author: icon
author_rank: Regular Contributor
timestamp: March 16, 2013, 04:07:13 pm
content: Newgrange?Sent from my GT-I9100 using Tapatalk 2

author: MacAttak
author_rank: Unknown
timestamp: March 16, 2013, 06:01:01 pm
content: Quote from: ee851 on March 16, 2013, 03:38:42 pmBut those aren't manmade.Sorry, but it had to be done.

author: staxquad
author_rank: Frequent Contributor
timestamp: March 16, 2013, 08:53:20 pm
content: Quote from: chicken on March 16, 2013, 12:11:37 am150 of those $15,000 batteries had to be replaced in the fleet of 50 over a year period, so something is cooking.They say they aren't over charging those batteries, but since they are being worn out, they might be over drawn.They use them for backup (not used until the engines shut down) and the brakes, but they brake on the ground and don't expect engine shutdowns so aren't worried?Tighter voltages? How about tighter current draw? (Or laying out what is going on instead of obfuscation and denial)Tighter voltages might be a hint that maybe the batteries are losing their balance and a cell is either going too low a voltage in use or too high while recharging.More insulation to keep isolated (and insulated to keep them warmer?) The cells still suffer from being folded and stacked, They should be flat and in single file which would make the package taller and longer, but immune from damaging the adjacent cells and with zero problems when there are no folds in the cells.Using 18650 cells would be safer, but they don't want the extra few pounds the package would weigh?They aren't convincing in their fix.Everlasting battery stink until they come clean.

author: senso
author_rank: Frequent Contributor
timestamp: March 16, 2013, 10:24:01 pm
content: So they use that new chemistry to lower weight and then add some steel plates, I smell it would be lighter with a more stable chemistry..

author: jerry507
author_rank: Regular Contributor
timestamp: March 18, 2013, 03:06:01 am
content: The case was ALREADY some form of metal, and I'd bet it was probably steel. They're simply sealing it so they can control the oxygen in the box.Sinnetts analysis is spot on. They can't figure out what went wrong, so look at everything again and try to fix any potential problem. Why is the forums general consensus they can't figure out what went wrong because they're incompetent? The thing burned, it isn't strange that there isn't enough evidence left.They've made a lot of good changes that won't really add much weight. This is a good example of quality engineering.

author: EEVblog
author_rank: Unknown
timestamp: March 19, 2013, 11:01:13 am
content: http://www.gizmag.com/787-lithium-ion-safety/26676/Back in the air in weeks?And a lousy 68kg added weight?That's down in the noise when you consider the variable weight of the hundreds of passengers and their luggage!

author: TerraHertz
author_rank: Super Contributor
timestamp: March 19, 2013, 11:42:56 am
content: Fromhttp://seattletimes.com/html/businesstechnology/2020561865_787batterybriefingxml.htmlQuoteHa. It would be nice if they mentioned what the resulting effective accessible charge to mass ratio is after the charge margins narrowing. So funny if the end result is worse than NiCads.

author: SeanB
author_rank: Super Contributor
timestamp: March 19, 2013, 04:02:12 pm
content: Probably would be now very close to NiCd ability, but with a very steep cutoff at low voltage, unlike a NiCd which will deliver power until it dies. If you have an oops moment in the air and need battery power I hope there is a "break tab and operate but will mean battery replacement needed" guarded switch that overrides the low voltage cutout for use when the fertiliser hits the ventilator and the battery is the only thing keeping the wings from becoming ground augers. No good going in Valuejet style with a battery that is still good but which says no more power.

author: staxquad
author_rank: Frequent Contributor
timestamp: March 19, 2013, 06:01:00 pm
content: Quote from: SeanB on March 19, 2013, 04:02:12 pmCurrent provided for airplane startup: Li 150A, NiCad 16Aweight: Li 28.6kg, NiCad 48.5kgIt was mentioned on PPrune that they balanced the cells in groups of 3. If that's the case, there's your problem. One cell goes low, damages, then they try to recharge, the 2 other cells go too high and damage, and with repeated use the battery goes critical from increased internal resistance.edit: Above seems to be erroneous information. The battery consist of 8x LVP65 in series. The cells are folded in 3 layers inside each LVP65, but that's one cell. (There's no 3 cells in parallel as mentioned in PPrune.) So balance, temperature, voltage min/max, charging monitoring should be done to each 8 cells in the battery. Monitoring should shut down the battery before becoming problematic.Also, the cells can damage from heat, and now they've insulated the cells even further to heat up even more than before. They should not have stacked the cells the way they have, with the additional insulation, they will just heat up more. They worry about one cell damaging the next, but let each cell damage more easily. The cells should be configured side by side along the walls of a box with a center courtyard of emptiness (a square doughnut) so that each cell is not adjacent to another. Right now the center ones are chocking. There's no confidence in their fix.When I charge my LiPo batteries, the charger monitors voltage and impedance on each cell showing if there is a damaged cell to be replaced immediately.One of my batteries had a cell too low that the balance charger could not deal with. So I discharged the other two to be at the same voltage as the low one and recharged. Have used for 4 or 5 cycles and the battery remains balanced. (there is a difference in impedance between the former low cell and the former two high cells that still remains, 3S 12V 8000mAh 30C; 9m?, 9m?, 5m? impedance; the same battery but 2S 12V 8000mAh 30C and healthy has 4m?, 4m? impedance). If I did not have a balance charger letting me know the condition of the cells, but just a wall wart, charging or using that battery might have resulted in a fire.Boeing should have hired a 15 year old RC hobbyist to design those batteries in the first place.They better be balancing each cell, monitoring each cell, not in groups of 3.

author: LaurenceW
author_rank: Frequent Contributor
timestamp: March 19, 2013, 06:16:21 pm
content: In some of the photos of a "still good" battery pack that I've seen, there is clearly supervisory/monitoring wiring going to each cell, but it doesn't look like it would carry different charging currents.SeanB, I have done a few informal experiments with 18650 lithium cells. The manufacturers tell me not to go below about 2.7V per cell, or damage is done. so I tried it! To be honest, there is precious little energy left in the batteries at this point, anyway.

author: staxquad
author_rank: Frequent Contributor
timestamp: March 19, 2013, 06:18:56 pm
content: Quote from: LaurenceW on March 19, 2013, 06:16:21 pmDid you monitor the cell's impedance before and after you conducted your experiment?You observe precious little energy outside the battery. Can you observe the chemical damage inside the battery? That's why you're supposed to check internal impedance.If you don't monitor, everything will always seem hunky dory, which is exactly Boeing's problem.

author: tom66
author_rank: Super Contributor
timestamp: March 19, 2013, 11:52:51 pm
content: So a NiCad weighs about twice the LiPo.A piece of baggage easily weighs the difference.I suppose, "every bit helps", but compromising (so very obviously) on safety worries me...

author: ee851
author_rank: Regular Contributor
timestamp: March 20, 2013, 05:47:30 pm
content: Does the steel battery box need to be vented? Why can't the box simply be sealed and filled with either halon or carbon dioxide, a gas that cannot support fire? Not to mention pressure sensors and temperature sensors.....Seems to be that keeping the contents of the box under one atmosphere of pressureall the timemight speed up the testing process.

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 20, 2013, 06:28:23 pm
content: So revert to the well proven batteries and then make sure at least 3 passengers onboard every flight are as skinny as Tiffany Yep. (Though that might not work out so well in Japan where most of the passengers are very skinny to begin with...)

author: staxquad
author_rank: Frequent Contributor
timestamp: March 20, 2013, 08:12:51 pm
content: Quote from: tom66 on March 19, 2013, 11:52:51 pmThe Yuasa LiIon used by the 787 can recharge at a 1C rate (recharge at a rate of 65 amps for one hour), discharge at a 5C rate and has a 65Ah capacity.Boeing designed the 787 around the current draw, weight, size and recharge time of the LVP-65 LiIon batteries.If a match is required for a current draw of 150A (for airplane powerup), they would need 9x the batteries used by the 777, with a resulting weight of 436kg compared to 28kg.Other batteries do not fit into the 787's current design.

author: Hypernova
author_rank: Unknown
timestamp: March 21, 2013, 12:19:32 am
content: IMO they should do the battery SiFi style - Have a row of ports on the side of the plane and eject any cell that catch fire!

author: chickenHeadKnob
author_rank: Super Contributor
timestamp: March 21, 2013, 03:54:51 am
content: Quote from: ee851 on March 20, 2013, 05:47:30 pmAs far as I know Li- cobalt and similar chemistries will continue thermal run-away even in an anoxic environment as the full complement for redox reaction is right in the cell. And a vent is "extremely" necessary, consider what will happen when all those evolved gases build up and finally breach your containment there by generating shrapnel, a good pipe bomb design.

author: G7PSK
author_rank: Super Contributor
timestamp: March 21, 2013, 09:45:20 pm
content: CO2 is not an inert gas especially if you have an electric arc as it breaks down. you would need Argon or Helium or possibly Nitrogen.