Is lithium ion battery technology still not there?

I think it's more just that they're an inherently unstable technology. Design them right, and they'll be OK, but it's easy to make mistakes, overlook things, etc., such that their inherent instability will lead to trouble.

I wouldn't be building them into aircraft.

Sylvia.

Yesterdays news:

"The [Japan] Transport Safety Board said in a report that the battery for t he aircraft's auxiliary power unit was incorrectly connected to the main ba ttery that overheated, although a protective valve would have prevented pow er from the auxiliary unit from causing damage."

Boeing and NTSB found no such miswiring on the JAL 787 where APU battery ca ught fire. ANA fire Japan is investigating was the EE-bay main battery, not the APU battery.

It's turned out not to be the battery but instead a wiring fault. Imagine that.

There was a wiring fault. That doesn't mean it caused the battery to catch fire. Indeed, were a wiring fault capable of doing that, one would have to feel that the design had no business being in the air.

Sylvia.

High energy density is inherently dangerous.

"T" stands for troll. No such wiring fault has been found or confirmed. JTSB is under extreme pressure to find an answer, the best they have come up so far is an "appearance" of miswiring through a protective "valve"- yeah, rght.

I wonder if ANY battery technology will ever be really safe. For example, lead acid batteries are well known and allegedly safe, yet we still have exploding car batteries: Concentrate enough energy in a small enough volume and you have the potential for simulating a bomb. Hydrogen fuel cells have a similar explosive potential. If radioactive battery technology suddenly becomes fashionable, we will have similar problems.

So, what will it take to make it a "proven" technology? Well, the FAA certainly has restrictions that follow its definition of safe. Such restrictions were applied to LiIon batteries for shipping and travel: where any more than 25 grams ELC (equivalent lithium content) or about a 300 watt hour battery is forbidden. Unattached (spare) batteries are not acceptable.

While it is legal to install an very large LiIon battery aboard a Dreamliner, it is apparently not legal to ship the same battery in a box as a replacement. Therefore, LiIon must be safe to install, but not to transport. The mind boggles.

The problem is that its very easy to demonstrate that something is unsafe, but impossible to prove that something is safe. This is the dilemma facing the FAA with all new technology. The tendency is to ban anything new until other industries shake out the bugs and generate some kind of track record. Approving the LiIon battery would have been considered safe by this logic because of all the laptop and cell phone batteries in use, and all the research into electric vehicle batteries. So, the FAA is stuck with a decision. Do they delay claiming "more research is necessary", or do they approve the Boeing band aids intended to somehow make an inherently dangerous device safe. Dunno.

It's certainly "there" for a lot of applications. I think that I would rather have a cell phone the size that it is now and undergo a 1:1000000 risk having my pants catch on fire than have one of the old ones that's as big as a shoe.

Larkin mentioned that high energy densities make for high risk -- he's right, but they make for high convenience and that can outweigh a lot of risk.

I subscribe to that too.... Having seen far too many 'incidents' with RC LiPos catching fire/bulging etc.

The Lithium-Ion battery is a logical choice for the application. I would b e cautious as to diagnosing the problem just yet. Certain lithium battery chemistries are more prone than others to fail with a fire. The battery in the Dreamliner (if my intel is good) is of a chemistry that would be bette r suited to remain on the surface of the earth. Failures could be a result of a few different scenarios, including a faulty cell to begin with, overc harging, and certainly mis-wiring the battery or a faulty BMU or charger bo ard.

I'm sure we will have an answer soon, although an answer grounded in realit y may never arrive. Just the way these things work out.

NEO

cell >to begin with, overcharging, and certainly mis-wiring the battery or a faulty BMU >or charger board.

But those failures are supposed to result in a dead battery (open ckt) and not fire, venting, or smoking. The safeguards against catastrophic failure, at least four internal to the cells, failed.

may never arrive. Just the way these things work out.

Don't count on it. Boeing is already working on designing it out of the system. United has removed the 787 from their flight plans . Now wait for the "out of an abundance of caution" bs from Boeing public relations.

ulty cell >to begin with, overcharging, and certainly mis-wiring the batter y or a faulty BMU >or charger board.

d not fire, venting, or smoking. The safeguards against catastrophic failur e, at least four internal to the cells, failed.

Not sure where you are getting your info, but open circuit failure of a Li- ion battery probably isn't going to happen. The particular recipe that the 787 is using is notorious for catching fire. Newer designs used to spin u p the turbines to light them off use a much more air-worthy chemistry

The batteries are not stuffed into the package like a can of sardines waiti ng to expand and catch fire. if you take a look at one of these assemblies you will see there is room to drive a small truck between rows of cells.

And yes, I agree, the batteries in the 787 will most likely be replaced by the end of the year with more forgiving units.

regards, N9NEO

ality may never arrive. Just the way these things work out.

ystem. United has removed the 787 from their flight plans . Now wait for the "out of an abundance of caution" bs from Boeing public relatio ns.

Ummm... what room?

Note the batteries on the left with the cells packed in rather tightly in what looks like a hermetically sealed metal box. There's some space between batteries, but not between the cells crammed into each battery case:

I Googled and could only find fried battery photos or original certification photos, both of which failed to show any gaps. A link to a photo showing these gaps between the cells please?

Agreed. Maybe an internal fire extinguisher or cooling system to prevent or restrict runaway lithium ignition. Looking at the top photo, there are already plenty of sensors.

Those batteries are a "proven" technology. However, use has shown that they are not only temperature sensitive, but that they are prone to thermal runaway; energy density so high as to cause fires - just like gasoline which has even higher energy density. Now there is a newer Li formulation that is NOT as temperature sensitive, and seems to NOT beprone to thermal runaway. Was not available back in the dinosaur age when the battery choice was made.

Methinks they put themselves between a rock and a hard place..the Dreamliner MANDATE was to make _everything_ as light as possible,and that stubborn attitude ruled out Lead-Acid and Nickel-Silver formulations.

and not fire, venting, or smoking. The safeguards against catastrophic fail ure, at least four internal to the cells, failed.

i-ion battery probably isn't going to happen. The particular recipe that t he 787 is using is notorious for catching fire. Newer designs used to spin up the turbines to light them off use a much more air-worthy chemistry

Things like shut-down separator, tear-away tab, and thermal circuit interru pters are intended to make the battery an open circuit, some permanently. T he first line of defense is the separator, a layer of which melts near ther mal runaway, and blocks all ion flow between electrodes. The others are bac kups. You're right, but not the way you think, "open circuit failure" /is/ "probably not going to happen."

technology.

I do not exactly agree with inherently dangerous. I say inherently difficult (to damn difficult) to do safely. See sodium-sulphur batteries. ?-)

y.

es.

Arre yo proposing that sodium-sulfur batteries are not inherently dangerous?