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podolefsky
08 October 2013, 1715
Starting a clean thread, because I actually think this is interesting, and important.

If you didn't see it, a Model S caught fire last Friday. It was on the street, and nobody was hurt. It was apparently the result of a huge chunk of metal from a truck piercing the battery.

I've seen lots of spec sheets for all different types of cells saying they pass a puncture test, and lots of Youtube videos showing cells either being punctured and doing nothing, or bursting into flames. Here we have, arguably, one of the best engineered batteries in the world bursting into flames after being punctured. Going with the recently popular topic of safety, this is worth paying attention to, especially since I don't think any of our bikes have a 1/4" steel plate protecting the battery, and it's sitting right between our legs. It's also a testament to how safe the Model S is - in spite of the fire, the driver was able to simply pull off and walk away from the car unharmed.

Elon Musk responded with an explanation, and some perspective:

http://www.teslamotors.com/blog/model-s-fire

robo
08 October 2013, 2050
Given the real scary amount of energy in combustible liquid gasoline, I am still surprised how downplayed this danger really is. I've also seen a lot of car-b-ques before and when given the chance, the fire usually expands into passenger compartment too.

Even aside from Musk's explanation, I would have said the car did very well.

teddillard
09 October 2013, 0258
Maybe you can explain a bit more why you feel it's interesting and important? I saw the story (I'd be shocked if most everyone here didn't), read it, and dismissed it. Considering how many cars are on the road, one car in an accident catching fire seemed like it was total media BS. Musk's comments, which I read almost in spite of myself, were a reasonable response to a non-issue. Is there something important I'm missing?

I don't see any way this has any bearing on our bikes, frankly, as you've tried to say above. If I get into an accident where some big spikey thing is going to puncture my cells, a chance-resulting fire is going to be the least of my problems...

"The geometry of the object caused a powerful lever action as it went under the car, punching upward and impaling the Model S with a peak force on the order of 25 tons. Only a force of this magnitude would be strong enough to punch a 3 inch diameter hole through the quarter inch armor plate protecting the base of the vehicle."

Something like that happens to a bike, you're just ****ed, on all counts... but I'm all ears. Oh, well, eyes.

Frank
09 October 2013, 0350
My only interest is that I can now reference Musk's response if necessary as somewhere there will be people pointing out how dangerous EV's are without a clue as to how many gas fires there are in cars. Btw, I'm a volunteer firefighter and have worked on a few vehicle fires; there's never much left. The model S seems to have fared pretty well.

Sent from my Nexus 7 using Tapatalk 2

jonescg
09 October 2013, 0432
Yeah if anything I think that Tesla will benefit from the story and outcome. Basically it highlights how well engineered their vehicles are.

With respect to bikes, Ted is right in that a battery fire on a bike is perhaps less of a concern than falling off. But the risk of fire is just as real on a bike should you rupture the pack. I'd say wherever possible, try to ruggedise your battery enclosure as best you can, without making it look like a tank, of course. Parking and charging in an open carport or shed is a good move too. Fires spread more easily inside houses...

I think it's relevant Noah :)

Nuts & Volts
09 October 2013, 0517
I have a feeling that the cells were not punctured. The way they are oriented in the car and to the impact it is more likely that multiple cells were crushed and this caused the thermal runway->fire. It's also possible that two busbars were shorted together at the same time which means cell level fuses (to protect against a cell short) will have less impact to suppress the short.

protomech
09 October 2013, 0717
Snarky.
http://autoblopnik.com/2013/10/08/industry-stock-market-react-in-wake-of-tesla-flat-tire/

Consumer Reports looked at fire incident rates for MY 2010 to 2012 cars and concluded that Tesla was in the right ballpark - not 5x better than gas, but we only have the one vehicle fire to go by.
http://www.consumerreports.org/cro/news/2013/10/tesla-model-s-fire-sparks-safety-concern/index.htm

There's probably an order of magnitude more vehicle-years with LEAFs and Volts than Tesla Model S .. they don't seem to be catching on fire much. I think I've heard of two LEAF fires (one may have been during a forest fire) and one Volt fire (homebrew charging rig, iirc).

podolefsky
09 October 2013, 0739
I have a feeling that the cells were not punctured. The way they are oriented in the car and to the impact it is more likely that multiple cells were crushed and this caused the thermal runway->fire. It's also possible that two busbars were shorted together at the same time which means cell level fuses (to protect against a cell short) will have less impact to suppress the short.You might be right. The report says the piece of metal was found somewhere else on the road. If it punctured you'd think it would have been found stuck in the pack.

podolefsky
09 October 2013, 0803
Yeah if anything I think that Tesla will benefit from the story and outcome. Basically it highlights how well engineered their vehicles are.With respect to bikes, Ted is right in that a battery fire on a bike is perhaps less of a concern than falling off. But the risk of fire is just as real on a bike should you rupture the pack. I'd say wherever possible, try to ruggedise your battery enclosure as best you can, without making it look like a tank, of course. Parking and charging in an open carport or shed is a good move too. Fires spread more easily inside houses...I think it's relevant Noah :)

Agree on all accounts. Battery catching fire is probably 0.01% of the danger involved in riding a bike. But I was thinking about various scenarios - you drop your bike, crush the pack. It's parked and someone hits it, even low speed while they're parallel parking. Or maybe part of your pack is really low on the bike and it gets crushed on a speed bump. You can't design for every possible scenario, but it's worth doing the best you can.

As far as why it's important - for the reason I said in the OP. A lot of marketing and spec sheets (which are, arguably, marketing) would make you think you could attack your battery with an axe and it would be fine. Maybe everyone knows this - seems to me, it doesn't get discussed much. Or worse, gets dismissed. The Tesla example is instructional - why did it happen? What kind of cells were they? How can we learn from it to make our bikes safer?

As far as the media response - meh - I couldn't care less what the media is all hyped up about. They'll be on to something else in 5 minutes.

Allen_okc
09 October 2013, 0839
which leads to other questions, and ive thought about it many times - what would happen if i wrecked my bike into another car, heaven forbid, but it happens - how would my battery pack hold up...

another question would be, how would a fireman who didnt realize he was using water to put out a fire on a electric motorcycle, what would happen? if it would be bad, then shouldnt it best if talk to our local firemen to ask what they would want to see on our bikes to make it safer for them to deal with...

frodus
09 October 2013, 0857
You actually want to use water on a lithium pack if possible. Sure it'll short things... But you're trying too cool the batteries. Most fires I've seen are due to thermal runaway and the best way to stop that is to cool them back down. Its what Motoczysz did at PIR when their pack overheated. Probably saved the motorcycle from being a total loss.

teddillard
09 October 2013, 0922
I was at a conference on Monday - the Alt Wheels Fleet Day, and they were talking about the EV plate that's available in Massachusetts now. Part of it is to support EVs of course, but the other part is to alert First Responders to the fact that it's an EV.

podolefsky
09 October 2013, 1117
The post by Musk said: When the fire department arrived, they observed standard procedure, which was to gain access to the source of the fire by puncturing holes in the top of the battery's protective metal plate and applying water. For the Model S lithium-ion battery, it was correct to apply water (vs. dry chemical extinguisher), but not to puncture the metal firewall, as the newly created holes allowed the flames to then vent upwards into the front trunk section of the Model S. Nonetheless, a combination of water followed by dry chemical extinguisher quickly brought the fire to an end.

BaldBruce
09 October 2013, 1948
Just wanted to point out the obvious. Not all Lithium chemistries are equal. Tesla chose high energy and high power (LCo and NCA) and thus they can and do catch fire if mutilated. This is not true of other Li chemistrries. Most of us are using LFP which trades off energy density for better safety and longer life. All batteries can release enough energy to start a fire and are themselves fuel. Some are just more volitale than others.

Link to the battery university summary done a little while ago on Li types: http://batteryuniversity.com/learn/article/explaining_lithium_ion_chemistries

Tesla is way safer than all gasoline vehicles IMO and the data over time will eventually prove it, even with their choice of higher energy density Li chemistries.

podolefsky
09 October 2013, 2324
Very good points, Bruce. That Battery U page is definitely worth reading - and noting which EVs are using which chemistry - AFAIK most recent production elmotos are using NMC. I believe RC lipo is essentially an LCo pouch cell?

Toni
10 October 2013, 0113
What is worth noting is that LiFePo4 chemistry that most of us seem to use, should be inherently safer than the cobolt & manganese based cells used in Teslas. A way safer for home conversions I'd think. Even in the event of puncture you'll most likely end up with smoke, but not fire.

PS. I had my battery cases built from 4mm aluminum sheet. Should protect them in the event of tipping over etc. minor mishaps...

PPS. Oh just noticed Bruce also pointed out the chemistry difference. (Didn't realize there was 2 pages of comments.)

teddillard
10 October 2013, 0340
Here's the video of the fire.


https://www.youtube.com/watch?v=Pphr7WyNBWU

Pretty much validates what Tesla said about the fire not making it into the passenger compartment.

Here are a few videos of mostly Luke trying to make a fire:


https://www.youtube.com/watch?v=LExMC5buoFg


https://www.youtube.com/watch?v=52h8IK0IdqI


https://www.youtube.com/watch?v=DrUYJCdW4yw


https://www.youtube.com/watch?v=p21iZVFHEZk


https://www.youtube.com/watch?v=8IBapfB0Imo

Finally here's a warehouse fire simulation:


https://www.youtube.com/watch?v=6OMv7St8EoU

Here's my own attempt at making a lipo fire video:


https://www.youtube.com/watch?v=YbI6EmL5GJ8&feature=youtu.be

After posting that I got a whole bunch of helpful comments about the fairly specific conditions I needed to make a proper lipo explosion. I even tried a few.

Non-issue IMO. My batteries, whether RC lipo or CALB or Headways are hanging right out there in the breeze, and will stay that way, because I don't see any reasonable argument that it's any more dangerous than this:


https://www.youtube.com/watch?v=Z87_evxrjz4

My personal favorite:


https://www.youtube.com/watch?v=Qke1cQC52GQ

I'm fairly certain all of these have been posted here before, under the Battery category (which this thread should be under, IMO).

I'd love to find the video of the TTXGP battery fire that was Muench, I believe, but if memory serves it was just kind of a smoldering event. I've seen more brushes catching fire than battery fires on the racing sites.

Battery fires will give you hours of pleasure on YouTube, but it's not something I even discuss with people who are asking about the bike. If they're not satisfied with the statement that they're safer than gasoline, I just ignore them. I may explain about RC and laptop batteries and the dangers of those, if they appear to be listening, but I strongly feel that the more traction you give to this discussion the more you're contributing to the mis-information noise. I ignore it, because anyone outside the community who's latched on to this as a talking point against EVs doesn't want to hear the facts anyway.


Maybe everyone knows this - seems to me, it doesn't get discussed much. Or worse, gets dismissed. The Tesla example is instructional - why did it happen? What kind of cells were they? How can we learn from it to make our bikes safer?

Sorry, but first, it seems to me like it's discussed constantly. Every time RC lipo gets brought up it's ressurrected. Second, yes, I feel out of all the safety issues in building and riding a motorcycle, it should be pretty much dismissed outside of the obvious "you're dealing with 80+ volts and 500 + amps" which is HUGELY more important to understand than what happens if they get punctured in some freak accident. (By the way, that would be my concern with using a material like 4mm aluminum sheet for your battery box, but that's been discussed here to death as well. I'm far more concerned about that shorting out in a crash than any punctures without it.) Finally, I don't see what I can learn about building my pack if this car - this car, mind you, got hit by a huge spike that went through 1/4 in steel.

What I take away from this is simple. Don't get hit by low-altitude missiles.

podolefsky
11 October 2013, 1326
Here's how much of a non-issue it is:


http://www.youtube.com/watch?v=8TqYZnVvSf8


http://www.youtube.com/watch?v=e3qGfocIOgM


http://www.youtube.com/watch?v=yc8NTkUKJ8k

In the last one, they weren't balance charging. It's not uncommon for people to bulk charge large lipo packs and only balance charge on occasion.

podolefsky
11 October 2013, 1327
..

teddillard
11 October 2013, 1341
Oh, right, OK. I thought this was about **** puncturing your packs in a laydown or accident, like the Tesla in the OP. My mistake.

podolefsky
11 October 2013, 1438
Oh, right, OK. I thought this was about **** puncturing your packs in a laydown or accident, like the Tesla in the OP. My mistake.

Yeah, it started there - and the thread went where it went. Nothing new about that.

More to the point, I reread your post with all the videos - if you feel OK with your cells "hanging out in the breeze" because they're safer than some drunk pyromaniacs, or because crashing is worse, I'm not sure what to say. I didn't start the thread to have an ideological debate - which is always the problem. It's not an ideological issue, at least it isn't for me or any of the people I've talked to who work with batteries for a living (read: experts). It's a well accepted fact. LCo cells, whether they're in a Tesla or hobby lipos in a bike, are volatile and dangerous. You don't have to accept it, but please don't get in the way of other people who are actually trying to have a rational discussion - about safety, which, I thought, was one of your favorite subjects.

teddillard
11 October 2013, 1459
Yeah, OK. I'll keep my opinions to myself, especially when they don't agree with yours.

podolefsky
11 October 2013, 1703
[deleted - frustration leading to snark - sorry]

BaldBruce
11 October 2013, 1912
Ted, your opinion that discussing battery fires propagates the myth has some validity, but isn't it more important to use these types of events as teaching moments? The slew of videos you posted clearly show the point that others are trying to make. The first video shows a LiPo of unknown chemistry and what can happen with that more volatile chemistry, while most of the others were of LiFePO4 types and they clearly demonstrate how much safer that chemistry is. (Headways for instance) TESLA will alway have this inherent issue because of their choice of chemistry. LEAF and Volt chose the Fe variety and while they can still burn very nicely as the crash test of the Volt proved, they are far less likely to self ignite from an external blow.

The fact that gasoline autos are far more likely to burn than other types is just that. A fact. Diesels also can catch fire, but are far less volatile. Battery powered autos are even less volatile. Every vehicle is carrying energy that can turn into a fire if not properly designed and operated.

Point I am trying to make here is simply that for our ElMotos, choose your chemistry and choose the level of risk and protection that makes sense to you. Just make informed dscisions...



Lets start with Li battery education. Far to many people (even here) are putting out confusing information. Li-ion and Lipoly are just descriptions of the electrolyte portion of the design. (LiPO is actualy short for Lithium Ion Polymer Battery.) Li-ion uses a liquid while lipo uses a solid. The choices of Anode and Cathode material are what make the energy density go up and down along with the electrolyte choice. It is also what make some chemistries inherently more volatile. I worked in an 18650 battery factory making Cobalt based cathode cells with a liquid electrolyte. Several times we lost control of a charging test rack and applied 12V to a 4.2V battery. Anybody ever play with the model rockets when they were a kid? That's exactly what the intense fire coming out the end of the can looks like!

I'll use LiFePO4 as my example for how the same chemistry can be used in both LI-ion and LiPoly. A123 pouch cells ae examples of this chemistry with a solid electrolyte, while Headways are an example of the exact same chemistry being used with a liquid electrolyte. Confused yet? Sorry for the soapbox......
.

teddillard
12 October 2013, 0307
Thanks, Bruce, nice to see you posting again, by the way.

Just to clarify, then I'm done. My "opinion that discussing battery fires propagates the myth" wasn't my point.

My point was that discussing the Tesla fire has no bearing on safety in motorcycles, simply because the accident was such an inappropriate comparison to what might happen to you on a bike.

Discussing the Tesla fire propagates the ridiculous mis-information about the Tesla fire, IMO. You want to talk about battery safety, label it "Battery Safety" so every jackass who wants to point fingers at Tesla won't find it and use our discussion to bolster their BS. But fine, go ahead and label it whatever you want.

That said, I totally agree with your points about understanding different chemistries, which is why I tried to make a contribution and find assortments chemistries in videos catastrophes. Unfortunately, there are few (if any?) that show puncture with a solid steel (conducting) object, rather than shooting with a gun or something (that could happen, just not too likely in the neighborhoods I ride.) (<---that was a joke.)

This is why I'm getting my buddy's nail gun and doing some tests of my own. I do feel it would be helpful to see what happens when you drive a spike through a fully charged CALB or Headway, since those are common cells we use. And yes, I'm going to do it with one of my RC packs because I need to see this for myself, plus my packs are hardcase - a requirement from the RC car racing community. I doubt it will make any difference, but I need to see it.

My other point was not about drunks etc., it was about the relative volatility of gasoline, 4 gallons of which are between my legs when I'm on my gas bike. Unfortunately, drunks lighting gas fires is about all you can find on YouTube to demonstrate it's volatility.

Every time RC lipo is brought up we go through the same pattern of discussion. There's plenty of information on it, there are lots of people using it, and Noah's opinion is not the only opinion, nor final word, by any stretch. If you want actual information and experience on RC lipo, and how to use it safely, you need to go to ES since we can't apparently even bring it up and discuss it here. I'd love to know who exactly are these "professional battery testers" and "experts" are, by the way, so I can understand their perspective a little clearer - otherwise it's just unsubstantiated opinion.

I don't even understand the comment about an idealogical debate. Completely baffled by it, actually, but spare me the explanation, I really don'te even want to hear it.

...

deep breath

...

On a point of order, I've really had enough of the snark, personal insults and bull****. It used to be fun to hash around opinions and thoughts here, some wildly different, even about very controversial subjects. If we can't disagree - if we can't call bull**** here and use some humor in poor taste without getting into a constant personal pissing match, then what exactly are we doing here? I tried to make a contribution to the discussion, albeit disagreeing with the basic idea that the Tesla fire could benefit our understanding of how to build our bikes, and I'm told that's obstructing or derailing the discussion.

One guy who used to be on here constantly and made some amazing contributions to the forum said to me the other day - "Oh, yeah, ElMoto? No time for it. More drama than Middle School." It seems a shame.

Talk amongst yourselves... done for now.

podolefsky
12 October 2013, 0919
If you read back over, you'll see that it may not have been pierced but just crushed. Whether that has bearing on motorcycles is up to whether you can draw the comparison - to something going either through the pack, or crushing it, or even just denting it. OK, your opinion is that what happens to a car has no bearing on what happens to a bike. Fair enough. I think most people would disagree.

Opinions and some humor is what makes this forum fun. I know full well that my opinion isn't the only one. On this one, I came out pretty strongly not just because I disagreed, but because I know so many people disagree, and there is so much evidence that volatile batteries *are* an issue that I thought your opinion was simply wrong. As the saying goes, you're entitled to your own opinion, but you're not entitled to your own facts. Your opinion seems to fly in the face of all the facts, which is why I consider it ideological.

But I also thought it was dangerous. You're telling people not to worry about something, people that are building and riding bikes, some for the first time - but it is clearly a danger. CLEARLY. This is where we break down, I think. I just don't understand how you can know everything you know and still be so care free about this issue. Maybe you could help me (us) understand with some logic or reason. I know about the gasoline argument - here's the problem:

It's not at simple as saying batteries are OK because gasoline is more flammable. We all accept the statistics, I think, and from a consumer point of view battery safety isn't something to worry about - BECAUSE THE ENGINEERS BUILDING THE EV ALREADY WORRIED ABOUT IT.

But for a builder, it is an issue (IMO+nearly everyone else). Gasoline and batteries are dangerous for different reasons. The question is, would we have those same statistics if Tesla (and Nissan, and GM, etc) hadn't worried about it? If they didn't think it was an issue, why did they surround their battery with a 1/4" plate? They thought and worried about it, and so should we. You didn't say "yes, they're dangerous, and here are some of the things you can do about it", you said they're "hanging out in the breeze", a non-issue. I consider that irresponsible. As irresponsible, in my opinion, as saying there are lots of ways to die, so don't worry about wearing a helmet. The logic just doesn't hold up, unless you are already committed to a point of view - which is ideology, not science or reason...or very helpful. I need a better explanation, maybe you could give us one (or if you already have, point us to it).

Maybe the title of the thread should be different, but it seemed like everyone got the point of the thread. What frustrated me, speaking of drama, is that we were having a pretty good discussion up until your post with the fire videos. Then nothing for almost a whole day (a long pause by elmoto standards). I sat patiently waiting, hoping someone else would jump in, so it wasn't just Ted and Noah again. But nothing. The whole discussion just stopped. Maybe it's just a coincidence...but I suspect people saw your post, saw where the thread was going, and checked out. If so, that's a major bummer - like your friend, a shame if people aren't contributing because they're tired of the drama.

To be clear, I'm not trying to just cast blame - I do take some responsibility for the drama. Trying to keep that in check.

podolefsky
12 October 2013, 1036
This is why I'm getting my buddy's nail gun and doing some tests of my own. I do feel it would be helpful to see what happens when you drive a spike through a fully charged CALB or Headway, since those are common cells we use. And yes, I'm going to do it with one of my RC packs because I need to see this for myself, plus my packs are hardcase - a requirement from the RC car racing community. I doubt it will make any difference, but I need to see it.

That will be great to see. I think Luke did a pretty thorough test on that Headway, but seeing a metal object pierce it and stay there will be useful info. Same for CALB. I've searched and searched for that kind of puncture test on large format prismatics and can't find one. I know companies do them, they just don't post their tests on Youtube :rolleyes:

teddillard
13 October 2013, 0351
Rather than simply repeat myself, or repost what I've already said to address the post above, I'd encourage anyone reading this to please go back and read my posts in this thread. If you have questions about what I feel is safe for battery enclosures, you can see that section in my book (http://www.lulu.com/spotlight/teddillard), or read my posts about my work battery modules here: http://evmc2.wordpress.com/?s=battery+module You can also contact me directly at ted (at) evmc2.com. I honestly don't know how to state my opinion any clearer, or validate it any better but I'd certainly give it a shot.

A basic version of what I say in the book can be found here: http://evmc2.wordpress.com/2010/09/12/mounting-the-batteries/
...and here: http://evmc2.wordpress.com/2010/09/12/mounting-the-batteries-part-two-essentials/

The book version has a little more.

If you would like to learn more about how many people use so-called "RC lipo" safely (AKA "facts"), see my thread here: http://evmc2.wordpress.com/2013/10/14/rc-lipo-safe-use/. I thought we'd put up a couple of similar threads in the forum, but I can't find them for some reason.

As there are some people who actually read the book and my posts, and do trust (or at least consider) my opinion, I feel like it's important to not let the above mischaracterizations, especially those of being irresponsible or unsafe, Noah has made of what I've said in previous posts stand unanswered. It would, in fact, be most irresponsible to let his post go unanswered. Please do me the courtesy of going back and reading them for yourself and try to understand what I'm saying, and contact me if you don't.

That said, I'm not going to continue to discuss this here when such obvious (and seemingly willful) misrepresentations and selective comprehension are considered acceptable.

edit:

That will be great to see.

Well, you're going to have to do it yourself if you want to see it. I was trying to plan it out and figure the angle and such that made sense and realized it made no more sense on a motorcycle than shooting a spike into the gas tank - right back to my main point. I'm not going to waste a $60 cell on modeling a freak accident, I'll leave that to whoever feels it's important enough.

jonescg
14 October 2013, 0443
I'll put my hand up and say I stopped reading (well I read, but stopped caring) once I saw you two arguing.

Otherwise it's a bit like watching two pro tennis players, executing perfect serves and smashing the ball over the net with aplomb from either end... of two completely different tennis courts.

podolefsky
14 October 2013, 0833
Point taken. I'm taking a self-imposed 1 week time out from everything except my personal build thread.

After that, the drama all gets put in check. Everyone has permission to hit "dislike" on me if they see this crap again...it'll help me keep a lid on it.

Richard230
22 February 2014, 0834
Speaking of Tesla again, but not about the latest fire story, City Bike reports that a 63-year old Tesla S owner ran over and killed a bicyclist while driving at 55 mph on Highway 1 in Santa Cruz last summer when he fell asleep at the wheel. The driver said it was not his fault. He is blaming the accident on Tesla for manufacturing a car with an "overwhelming new car smell". He says that is what caused him to pass out while driving and kill the bicyclist. :mad: Fortunately, the DA is not buying his story and is charging the driver with vehicle manslaughter. :)