One of my ongoing ‘burn’ moments comes when a project is 3/4 done and someone wants to change the ‘spec’. Even a minor specification change can “have issues”.
So with Boeing and the Lithium Battery Fiasco, “what were they thinking” came to mind. Many of us have heard of laptops with lithium batteries bursting into flames. A simple quick check of lithium batteries shows they have a flammable organic electrolyte with lithium in it. Sometimes all the little lithium bits can line up and short out, overheating. That, then, causes the electrolyte to vent and that can then be ignited. Hot organic with metal bits in it being sprayed into air; what could go wrong?
Yet some lithium batteries don’t do that so much. Little is heard of cameras bursting into flame, for example. The “why” is that the primary Lithiums used in cameras (the disposable batteries) are one kind of chemistry. The rechargeable lithiums come in several chemistries; each a bit different and with different levels of performance (and risk).
As a bit of a ‘good news bad news’ there’s a bit of a smoking gun (IMHO) on the Boeing batteries. IFF this is the case and they recognize it, a “fix” could be a simple as swapping to a different, known, battery. Otherwise they could be in the soup for a long time. (Especially if they keep a more risky chemistry cell for, um, liability or ego reasons).
Boeing looks to boost 787 lithium ion battery service life
By: Jon Ostrower
12:00 14 Jun 2008
As Boeing activated the electrical system of its 787 for the first time last week, the airframer acknowledged that it was exploring a change to its power system for production aircraft due to longevity concerns.
Boeing will move away from its original lithium ion battery design for its main and auxiliary power units, flight-control electronics, emergency lighting system and recorder independent power supply. Instead, Boeing is investigating the incorporation of manganese inside the lithium ion battery to boost service life.
Boeing has not determined which 787 will be the first to receive the new battery modifications, although multiple programme sources have told Flight’s FlightBlogger affiliate that the new battery could be introduced as early as Airplane Seven, the first production 787 scheduled for delivery to All Nippon Airways in the third quarter of 2009.
The sources add that the first six flight-test 787 aircraft will have the original feature lithium ion batteries, but will be retrofitted with new batteries before delivery to airline customers.
The use of lithium ion batteries is to be the first application of the technology on a commercial jetliner.
The US Federal Aviation Administration voiced its concerns about the use of lithium ion batteries in an April 2007 proposed special condition.
At the time, the FAA said that the 787-8 would have “novel or unusual design features” and required, “additional safety standards that the [FAA] administrator considers necessary to establish a level of safety equivalent to that established by the existing airworthiness standards”.
The FAA cited three specific safety concerns about lithium ion batteries, which included overcharging, over-discharging and the potential flammability of cell components.
Boeing underscores that the change in battery technology is unrelated to any safety concerns and the airframer is fully complying with the 2007 Special Condition.
Japan’s GS Yuasa supplies the batteries for the 787 Dreamliner.
So there is a lithium ion battery in common use, though it is still ‘novel’ for passenger aircraft. FAA is a bit worried about it. Boeing says “not to worry”, but then does a battery chemistry swap after testing as they go into production.
Now I don’t know that the manganese lithium chemistry swap ’caused issues’, but I do know it’s a very bad idea to swap components after the testing is done. It’s also a bad idea to swap components that are sensitive to things like charge rates and pressure cycling and discharge depth and expect the new chemistry to be a drop in replacement for the charge and discharge management circuitry. EVEN if they “usually are”.
Gives a pretty good idea why Lithium batteries can burst into flame. It talks about the small cells used in things like laptops.
Implies that the manganese chemistry is more safe:
Chemistry, performance, cost, and safety characteristics vary across LIB types. Handheld electronics mostly use LIBs based on lithium cobalt oxide (LCO), which offers high energy density, but have well-known safety concerns, especially when damaged. Lithium iron phosphate (LFP), lithium manganese oxide (LMO) and lithium nickel manganese cobalt oxide (NMC) offer lower energy density, but longer lives and inherent safety. These chemistries are being widely used for electric tools, medical equipment and other roles. NMC in particular is a leading contender for automotive applications. Lithium nickel cobalt aluminum oxide (NCA) and lithium titanate (LTO) are specialty designs aimed at particular niche roles.
but it also has a different set of electrical characteristics. That leaves me wondering just how much of a real drop in replacement they can be…
The most commercially popular negative electrode material is graphite. The positive electrode is generally one of three materials: a layered oxide (such as lithium cobalt oxide), a polyanion (such as lithium iron phosphate), or a spinel (such as lithium manganese oxide).
The electrolyte is typically a mixture of organic carbonates such as ethylene carbonate or diethyl carbonate containing complexes of lithium ions. These non-aqueous electrolytes generally use non-coordinating anion salts such as lithium hexafluorophosphate (LiPF6), lithium hexafluoroarsenate monohydrate (LiAsF6), lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), and lithium triflate (LiCF3SO3).
Depending on materials choices, the voltage, capacity, life, and safety of a lithium-ion battery can change dramatically. Recently, novel architectures using nanotechnology have been employed to improve performance.
Lithium-ion batteries with a lithium iron phosphate cathode and graphite anode have a nominal open-circuit voltage of 3.2 V and a typical charging voltage of 3.6 V. Lithium nickel manganese cobalt (NMC) oxide cathode with graphite anodes have a 3.7 V nominal voltage with a 4.2 V max charge. The charging procedure is performed at constant voltage with current-limiting circuitry (i.e., charging with constant current until a voltage of 4.2 V is reached in the cell and continuing with a constant voltage applied until the current drops close to zero). Typically, the charge is terminated at 3% of the initial charge current. In the past, lithium-ion batteries could not be fast-charged and needed at least two hours to fully charge. Current-generation cells can be fully charged in 45 minutes or less. Some lithium-ion varieties can reach 90% in as little as 10 minutes.
So we have a swap of chemistry in the cells. While we don’t know what the old chemistry was, exactly, it was likely about 1/2 V different. That means adjusting the chargers, the voltage regulators, the monitoring and alert circuitry. WAS all that done?
While I’m sure the engineers were involved in the swap and designing a swap procedure, I also know that there is a world of difference between “Design using FOO and you have 3 years” vs a “suit” showing up and saying “Can we swap to BAR? OK, you have 3 months.” That is a large part of why ‘last minute changes’ are often the source of “problems”.
There is a giant gap between “I think I can make it work” and “This is my best design”.
OK, all speculative. But speculation based on a lot of years working projects and dealing with FUBARs caused by last minute changes to the “spec”.
Were I at Boeing and / or the FAA right now, I’d be looking very hard at the option of swapping back to the original designed in and tested / accepted battery and just yanking the ‘swapped in after testing’ ones that seem to have a bursting into flame problem
In related news, the battery maker stock is way down hard, while Boeing is only down a little bit. IMHO it ought to be the other way around. Most likely the battery maker makes a fine battery, that Boeing has put in the wrong place without enough testing. Then again, in the search for someone to take the fall, it would be easy for Boeing to swap suppliers and announce it was all better now…
Personally, I’d avoid both of them for a while. Fast trades can catch the ‘dead cat bounce’ as the short sellers exit the trade (likely in a couple of days) but the risk is that months from now they still have not fixed the ‘root cause’ and another round of batteries starts to smoke. So, for example, if it IS the chemistry change, just putting in a different make of the (now in production) ‘wrong’ chemistry cell is not going to fix things permanently.
If they DO swap to the old tested cell chemistry, they will likely come back for a second try at the chemistry swap in a few years as the cells need replacing, and we could end up with a repeat then. One would hope someone, in a suit, somewhere, is listening to the ‘battery guy’ that they paid no heed before… (At an aviation company, the airframe / wings aeronautics guys are ‘hot’ and the engine / powerplant guys right behind them. Most other folks are ‘support staff’ just expected to make the other stuff you glue around the important stuff… but not expected to be ‘stars’, nor typically treated like one. I think someone may be learning that the ‘battery guy’ matters. Just like Air Bus learned that the ‘pitot tube guy’ mattered when they lost a plane from those plugging up. It really is important to remember that every one of those parts matters, as does the person who designs it.)
For now, I expect they will get this fixed in about a month. But I’d watch out for hints of a reprise in about 2 to 3 years at battery replacement time…