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[kcoplan]

Lots of news stories about the fire risks of lithium ion batteries, what with the Boeing 787 being grounded and all.  NPR had a piece on this.

http://www.npr.org/2013/01/18/169729162/powerful-but-fragile-the-challenge-of-lithium-batteries

And the New York Times did too

http://www.nytimes.com/2013/01/18/business/lithium-ion-batteries-are-powerful-with-a-drawback.html?_r=0

Now my wife wants to know if my Zero S is going to burn the house down.  Do any of the battery experts on this board have a convincing reason to believe that the batteries on the Zero are much much safer and fail safe than the lithium ion batteries the FAA approved for critical aeronautical use and which grounded the Boeings?

-Karl

[protomech]

We'll have to wait and see the results from Boeing's investigations.

#1 difference between the 787 batteries and the 2012 Zero batteries are the battery chemistries, lithium cobalt oxide (LiCo) vs lithium nickel manganese cobalt oxide (NMC). Speaking generally, LiCo is not an inherently safe chemistry; when properly cared for and used under the correct conditions it is fairly safe, but if it is abused then it can vent or enter thermal runaway. (My general understanding is that either the cobalt or the cobalt oxide is exceedingly reactive and the chemistry is not very stable .. but I'm neither a chemist nor a battery expert, so..)

#2 difference is the battery management. On elmoto someone posted a link to a whistleblower at Securaplane detailing numerous skipped/bypassed tests and shipped faulty equipment. Securaplane manufactures the battery chargers for the GS Yuasa LiCo battery for the 787. The two 787 fires both seem like they occurred when charging (one on the ground, one in the air) .. the Zero BMS is designed to do the same thing the Securaplane BMS SHOULD have done, disconnect the contactor when an overvoltage condition exists.

Bottom line is that anything can be abused. I have approximately 25 gallons of explosive liquids in my garage now. I'm not unduly worried because I know the risk is minimal .. but under the wrong conditions, gasoline is exceedingly dangerous. Similarly for lithium batteries.

Take a look at the three videos posted by liveforphysics here:
http://www.elmoto.net/showthread.php?2166-LiPo-Dreams-Does-Anybody-Else&p=27837&viewfull=1#post27837

Note that you may not want to watch the first two with your wife present, if you're trying to build up a case ; )

The third video shows some abusive testing of a 20 Ah NMC cell. Much like the ones used in our bikes. *cough* You can see another abusive test of another 20 Ah NMC cell here:


Skip to 2:40 for the NMC cell test. Cell has been physically abused and overcharged to 4.46V .. then the tabs are hit with an arc welder. The tabs get hot but nothing terribly exciting happens. Unlike the rest of the video..

LFP is a nut.. he seems to really enjoy abusing cells. But I trust his judgment over what cells are safe and what cells are not.

[Doctorbass]

It is NOT all Li-Ion battery chemistry that are dangerous.

The LIMN and LiFePO4 cells are known to be more stable and that can take more abuse.

I have my garage with probably 2000+ cells spread around  that i played with for ebike projects and others that i tested, tested tested, dischrged and charged etc and never had a single fire event.

Alot of short circuit as well but no fire.

The LiMn and LiFePO4 chemistry can take alot more error of use than Li-Ion Cobalt ( laptop)or  Lithium Polymer ( RC toy).

Unfortunatly The fear of lithium battery has been amplified by the media over the last years alot more than the benefit they can offer to the modern world...

Doc

[NoiseBoy]

Its staggering how hard people try to find arguments against EV's. Like the guy on off the grids Facebook page that is keeping his old car because lithium batteries contain "horrible chemicals" but he hadn't even thought about the frighteningly long list of safety warnings associated with automotive diesel fuel. I'm certain that petrol heads are nervous because they know full well that EV's are or soon will be better than their ICE.

[kcoplan]

Thanks for the links, Protomech.

Makes me feel better about the NMC batteries in the bikes.

Why don't they just use NMC batteries in the Boeings, too, then?

Karl

[Richard230]

In an article by the Seattle Times there were a couple of comments about needing to have very good quality control when building Li-ion batteries.  I think this is a problem with many industrial products that have recently been moved from a research laboratory to a manufacturing plant.  When the products are being built, the manufacturer starts thinking about ways to cut costs and speed up production, including how to reduce the time required to properly train their workers.  With most companies choosing the low-bidder (something that BMW seems to have been doing a lot lately), these sorts of problems can occur unless rigid quality control is implemented - something that costs money and slows down production.  I might add that BMW doesn't seem to mind when their parts fail in service - as long as they can blame the supplier and make them pay for the repairs and recalls.

My guess is that is the real problem here.  The battery or BMS (or both) manufactures cutting corners and Boeing not double-checking to see if the supplier is meeting their specifications.  Hopefully they will learn a lesson and resolve the issue permanently - but that requires continual vigilance, which tends to be forgotten when the next cost-cutting mandates are proposed.

[protomech]

Aircraft are stupidly complex and have a very long design time - possibly as many as 10-15 years in the commercial realm. It's possible that Boeing could update the battery tech, but it would probably have to recertify the entire aircraft. May have to do that anyways now that the FAA is involved.

Nissan Leaf and Chevrolet Volt (supposedly) use a lithium manganese spinal battery chemistry. This is the chemistry Zero abandoned in 2011 for NMC in 2012, and lithium manganese rich (Mr?) for 2013.

[trikester]

I fly electric R/c model airplanes. Most of them use lithium polymer (commonly called LiPo by users) batteries because those have the absolute highest power to weight ratio of any of the lithium types. However, much is written about their flammability if abused. They seem to be the most easily ignited and 3000 degrees when burning. All of the instructions that come with the batteries and the chargers say to never leave those batteries unattended while charging. If one attends a model airplane product show one can see a number of companies selling fire proof enclosures to put the batteries in while they are being charged, so that a battery fire will not spread to the surroundings.

I take all of these warnings seriously when charging my lithium polymer R/C plane batteries. Fortunately, for my piece of mind, this is not the type of lithium battery used by Zero. It also means I don't have to hang around my bike for six hours, while charging.

Trikester @wherediputthatfireextingusher.com

[benswing]

The battery chemistries are not the same.  The Lithium battery in the Zero, and almost all electric cars, is different from the Boeing battery.  Lumping them together was a rookie mistake by the authors (or willfully harmful toward EVs), and they should have pointed out the difference if they were legitimate journalists (instead of inaccurately identifying them as similar). 

[protomech]

CNN reports that the GS Yuasa batteries were not overcharged - or at least they never saw more than 32 volts (seems to be 8 modules in series per enclosure = 4.0 volts per cell)
http://www.cnn.com/2013/01/21/travel/boeing-dreamliner/index.html