Investigators in Japan say 787 battery was not overcharged
TOKYO (AP) - A lithium ion battery on a Boeing 787 that overheated during an All Nippon Airways flight earlier this month experienced a sudden drop in voltage and was not overcharged as previously thought possible, Japan's transport safety agency said Wednesday.
Japan Transport Safety Board chairman Norihiro Goto told reporters the jet's data recorder showed the main battery, used to power many electrical systems on the jet, did not exceed its maximum voltage. That contradicts an earlier assertion by the agency as it investigates with the U.S. Federal Aviation Administration.
All 50 of the 787 Dreamliners that Boeing has delivered to airlines were grounded after the emergency landing by the ANA flight in western Japan on Jan. 16. Boeing has halted deliveries of new planes until it can address the electrical problems.
Goto said the maximum voltage recorded for the battery was 31 volts, which was below its 32 volt limit. But the data also showed a sudden, unexplained drop in the battery's voltage, he said.
Aircraft do not usually use the kind of lithium ion battery chosen for the 787, and investigators are still struggling to figure out what may have gone wrong.
"It's not that it is difficult, but that we are not so familiar with it," Goto said.
The Transport Safety Board said it also will study the aircraft's auxiliary battery and compare data from each.
Investigators from both sides are probing GS Yuasa, the maker of the charred battery, and are examining the battery using CAT scans at a facility of Japan's aerospace agency.
U.S. investigators also said that they found no evidence of overcharging in a battery that ignited on a Japan Airlines Boeing 787 as it sat on the tarmac in Boston's airport earlier this month.
US officials defend handling of Boeing 787 mishaps
Meanwhile, Obama administration officials are struggling to defend their initial statements that the Boeing 787 is safe. They are promising a transparent probe of mishaps involving the aircraft's batteries.
Transportation Secretary Ray LaHood stood by his Jan. 11 assertion that the 787, Boeing's newest and most technologically advanced airliner, was safe. At that time, he and the head of the Federal Aviation Administration, Michael Huerta, declared the plane fit to fly despite a battery fire in one plane.
Five days later, following another 787 battery mishap in Japan, LaHood and Huerta ordered the lone U.S. carrier with 787s to ground the planes. Authorities in other countries swiftly followed suit.
Huerta, joining LaHood, said FAA is working as quickly as possible to find the cause of the problems.
Japan Transport Safety Board chairman Norihiro Goto told reporters the jet's data recorder showed the main battery, used to power many electrical systems on the jet, did not exceed its maximum voltage. That contradicts an earlier assertion by the agency as it investigates with the U.S. Federal Aviation Administration.
All 50 of the 787 Dreamliners that Boeing has delivered to airlines were grounded after the emergency landing by the ANA flight in western Japan on Jan. 16. Boeing has halted deliveries of new planes until it can address the electrical problems.
Goto said the maximum voltage recorded for the battery was 31 volts, which was below its 32 volt limit. But the data also showed a sudden, unexplained drop in the battery's voltage, he said.
Aircraft do not usually use the kind of lithium ion battery chosen for the 787, and investigators are still struggling to figure out what may have gone wrong.
"It's not that it is difficult, but that we are not so familiar with it," Goto said.
The Transport Safety Board said it also will study the aircraft's auxiliary battery and compare data from each.
Investigators from both sides are probing GS Yuasa, the maker of the charred battery, and are examining the battery using CAT scans at a facility of Japan's aerospace agency.
U.S. investigators also said that they found no evidence of overcharging in a battery that ignited on a Japan Airlines Boeing 787 as it sat on the tarmac in Boston's airport earlier this month.
US officials defend handling of Boeing 787 mishaps
Meanwhile, Obama administration officials are struggling to defend their initial statements that the Boeing 787 is safe. They are promising a transparent probe of mishaps involving the aircraft's batteries.
Transportation Secretary Ray LaHood stood by his Jan. 11 assertion that the 787, Boeing's newest and most technologically advanced airliner, was safe. At that time, he and the head of the Federal Aviation Administration, Michael Huerta, declared the plane fit to fly despite a battery fire in one plane.
Five days later, following another 787 battery mishap in Japan, LaHood and Huerta ordered the lone U.S. carrier with 787s to ground the planes. Authorities in other countries swiftly followed suit.
Huerta, joining LaHood, said FAA is working as quickly as possible to find the cause of the problems.
al_wa has brought up a very important point, that has been bothering me. Cell voltage balance within the series connected battery, could well be the problem. Can anyone tell me whether cell voltages are accessible from outside this battery? If not, then tiny differences, as in cell self-discharge current, would accumulate, without the possibility of correction, and create important differences in cell state-of-charge, such that, during charge, an individual cell could exceed it's 4.2V limit, without the battery exceeding it's voltage limit.  Of course, a rather simple circuit, like the one shown on the cell balancing page of www.orbicinstitute.org could run within the battery, without the cell interconnections being brought out.
 "Investigators in Japan say 787 battery was not overcharged" This a little misleading, the terminal voltage of the battery may not have been any higher than 31 volts, but that says little about the individual cells. I believe there are 8, LVP 65 cells. Nominal voltage 3.6 x 8 = 28.8 Vdc , absolute maximum charge of 8 x 4.2 = 33.6 Vdc  http://www.gsyuasa-lp.com/aviation-lithium-batteries
Assume the batteries were at a nominal state of charge of 28.8 volts, an individual cell could increase from 3.6 volts well in excess of the cell maximum of 4.2 volts, without the battery terminal voltage going beyond 31 volts. When that cell catches on fire and dies the battery terminal voltage would drop by one cell.
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The people working the problem know all this stuff and will figure it out but reporting the battery was not overcharged
without knowing if each individual cell was not overcharged is ludicrous.
 @al_wa Yup. That's what I said earlier about the individual cell voltages.Â
 @Seahawker And i gave you a thumbs up.
Gee, I dunno, maybe the batteries are rated too high? 31 volts is pretty close to 32 volts no? According to their specs, the battery wasn't overcharged, but yeah...probably was.Â
...I think this is a reach but who is to say the sensor was not reporting accurate information.. I mean batteries do not just catch fire because they are having a 'off day' if the batteries were all in the same batch perhaps they were damages prior to install then ... either way their is an issue here and I don't think it is a plane design issue... the batteries ... that or the battery was not secured properly shifted and shorted on a piece of metal... I am really interested to know what the hell happened ....
Perhaps if the battery was shorted out that would explain a voltage drop and a burn out....
The battery wasn't overcharged but the passengars were! zing!! couldn't resist.
Goto said the maximum voltage recorded for the battery was 31 volts, which was below its 32 volt limit. But the data also showed a sudden, unexplained drop in the battery's voltage, he said.
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So what they think  is the battery as a "Whole" didn't exceed the the maximum  32 volt limit so over charging wasn't the cause, but what about each individual cell???? The total battery voltage recorded might have been 31 volts but that doesn't tell you how many volts each cell had in it.  you could have had 1 or more cells that were overcharged.  For example.................  There are multiple cells in each of those batteries on the 787. so if any of those cells got above their max voltage  then there's the problem.  I'll explain ..............  Lets say you have 6  5 volt cells wired in "series"  in each battery,  that now makes the battery have a total of 30 volts. So what i'm saying about the 787 battery is If you have 31 volts in a  6 cell battery and 3 of the cells were at 3 volts, then  the others 3 cells would have been over charged at 9+ volts each and the battery voltage would've only read 31 volts. This tells me that they only looked at the "total battery voltage" and not the "individual cell voltage" and I'm betting that this is what cause the "Lithium battery"to catch fire. Lithium batteries are very dangerous and will catch fire  when a cell gets below a certain voltage or over a certain voltage..  This also would have made a dangerous under charge voltage in the 3 cells that were at 3 volts and cause the battery to explode and catch fire. This is very common in lithium cells when you don't "Balance" each individual cell when charging.
 @Seahawker A cell that is overcharged above 4.2 volts is hazardous and may catch fire. A cell that is discharged severely below 3.0 volts may not recover and cause loss of the cell.
 @al_wa I've had lipo cells get below 3.0 volts and "puff" up and burn in the past. My Castle Creations brushless speed controller allows me to set the "cut off voltage" to protect my battery pack  so this wont happen. If you apply to big of a amp draw to the  pack  it can catch fire also.Â
Your CC does not monitor individual cell voltages. It only senses the so called Terminal voltage of the pack. Big difference.
 @Seahawker Low cell voltage as a result of discharge current beyond the ratings like 40C on a 20C cell will 'Puff" a cell.Â
Cell balance is critical. But, you can have cells that are low or high,and the battery will be perfectly stable. But if a load or a charge is then applied incorrectly, that is when things go boom. I've had several lipos go off on me, but that was about 7 years ago when they first came out. The cell technology has not changed much, but the battery/cell monitoring systems have -which the key here.Â
 @jeff Exactly. I remember when lipos first came out before then offered individual cell charge balance boards. I think they didn't have a balanced cell battery and one or more of the cells were way off and not even close to balanced.Â
I know nothing about electronics or electrical systems but when ever I have done any wiring I have always, at a minimum, doubled the capacity over it's intended use. In fact it's that way with a lot of things out there in the real world. If you were hanging onto a rope over a cliff would you want that rope rated at your body weight, or greater?
Undervoltage is just as dangerous as overvoltage when it comes to Li-Ion batteries. Â For this purpose, safety mechanisms are built-in in every single cell, to prevent such a scenario.
I think there's something broken in there :).
Lithion Polymer, not Ion. Two different birds.
But you are correct. Cell balance is the key with these.
I'm going with the lithium battery which as everyone knows can spark a fire whether it's your cell phone (several instances) or your laptop (again several instances). If the battery didn't overcharge and it's not the electrical, it falls to the actual battery and how it's made to include testing (did the company that make these test them for altitude changes, speed variance etc. I'm not an engineering by a long shot but common sense tells me that these weren't tested in a real plane prior to the 787.
@asceptictoo Chances would be they failed to pressure test this batteries. Just like when you fly a can of sardines, the can bulge when you arrived to your destination from the pressure. Now you combine that pressure with heat and electricity.
It's all about the design!! Or the lack thereof!
This plane was never in a mock up situation where they could have access to all things having to do with anything and everything concerning the plane and it's functionality. Whether it is a plumbing issue or electrical....Going off a computer generated creation is damaging to the entire aircraft industry!
THEN you have a batter that on this plane that is said to be below it's voltage capacity of 32 volts being at 31 volts. WELL ISN'T THAT MAXED OUT???? Might as well be over 32 volts.
That should have caused a fire or over heating.
TOOOOOOOOOOO may many people or shall we say inexperienced people built this plane! This is the only plane in the entire fleet having 75 to 85 percent built by everyone but the Boeing Company!!
They merely assembled it!
Having brought strangers on sight to the company doing our job, not knowing their own job or how we do business.
Go figure!!
This plane was doomed in my opinion from the start!
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Lipo Cell nominal voltage is 3.7V. Fully charged its 3.9, fully depleted (safely) is 3.2V. So, 31.0 is far from 32.0 in this case.
And FWIW, the 787, jus tlike all Boeing planes, go through 100's of thousands of hours of test flights with the intent of maxing out systems like these to flush out problems just like this.
@reelin21 if you don't even have any engineer education or work experience, please stop with your non sense on the battery voltage limit.
 @PuzzleFighter  @reelin21 He's actually partly correct, much of the manufacture of the 787 was outsourced but assembled here. the entire wing assembly was outsourced, among other things. Either way this is going to come back and bite Boeing, especially if their engineering Union goes out on strike.
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And before you guys say "oh well there are tons of engineers that would love to get a job there as replacements!" Keep in mind that nearly all of them would have to be trained, which would ultimately cost more money than its worth. Boeing screwed the pooch when they rejected SPEEA's offer to extend the current contract with the already agreed to changes another 4 years. I'm sorry, but if I was the owner (or head boss which ever) and my union offered that, especially when facing major issues with a new product, I would take it in a heartbeat!
@reelin21 If your car battery was at 11 volts would you feel safer? I would say that last time I checked 31 is less than 32 so the battery was not maxed out. Even at 32 or 33 volts i think "Should have caused a fire or overheating" might be a bit of an over statement.
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 @reelin21 Wow...  Wouldn't yo figure that at 32V, there's still some sort of safety factor built in?  And by the way, the 777 wasn't mocked up either. Â
 @Pierce Co Repub  @reelin21Â
Pierce co repub..............but the 777 was engineered and built by mainly US workers
 @luvegas the 787 Airframe was engineered here in the US just as the 777 was. Â
 @reelin21 Dude, you don't make any sense, FOCUS DANIELSON.......
 @Notyouraveragejoe  @reelin21Â
Reelin21.....I know exactly what you mean. I guess you have to work there to understand
So far it is looking more and more like the problem is not with the plane but with the battery maker. But it must still be those union workers at Boeing for installing the batteries!
 @4ShotLatte LOL yep them union haters are going to blame SPEEA and the IAM regardless because they have nothing better to do than bash on those that have a better way of life and a better income then they do!