zacster

I've been fearful of the Lithium ion batteries in my bike lights, and I ride a carbon fiber bike most of the time. Should I be worried about the battery catching fire and setting my bike ablaze?

OK, now the real reason for my post. Reading about the Boeing 787's problems all I can think is that this is a known problem with Li-ion batteries. I've read about the Tesla cars too, and I think the same thing. I DON'T want to be in a vehicle that depends on these things, especially one that's 38000 feet up. It just seems too risky. A single battery may never give you a problem, but put an array of thousands of 18650s in parallel and you're bound to have a problem.

I think I'll pass on the Tesla, and wait for them to come up with a solution for the 787. My Keygos light OTOH is fine, but even with that I don't let it charge unattended overnight.

Burton

Single cells are never a problem. Battery packs made of multiple cells (more than 4) have been an issue in NiCAD and NiMH as well as Lithium. Probably one of the reasons the cheapest lights use the lowest voltages - it reflects a minimum number of cells and doesn't require a sophisticated (expensive) battery management system.

In any case - as long as your light is attached to the bars and not the frame - its highly unlikely any malfunction could cause your bike to crash and burn.

zacster

I wasn't being serious about the bike. But the "sophisticated" battery management still has problems, and Boeing is finding out the hard way. They have a huge engineering budget and still don't quite have it down. Tesla is a small company and I'm sure we'll be reading about the $75,000 car that caught fire once they actually start selling a few.

Garfield Cat

Tesla has several stockholders and one is Toyota. The RAV4 is scheduled to come out as an all electric car, just one version of RAV4's many. Much of Tesla technology goes into cars now.

Come to think about it, I'll ask the engineers here in So Cal.

pdlamb

I think it's a fair question, are Li ion batteries dangerous? The problem is that lithium reacts with water, so to make a battery, you have to use an organic solvent (flammable). If there's a problem that ends up with a leaking or ruptured battery, it can catch fire; not like your old carbon-zinc and alkaline batteries, where a leak or rupture makes a mess of corrosive gunk but the water evaporates off.

Now, what happens when a lithium battery catches fire? If it's one of the watch-battery sized things in a tiny light, there's enough solvent to burn for a few seconds; not a big problem. A 60-pound industrial beast? They don't make those any more because there's no safe way to dispose of them. Somewhere in between are the (roughly) A-sized batteries in an electric car, and the AA or AAA in a bike light. Ask yourself (or try this outside), how long can the paint thinner in one of those sized containers burn? Remember a pretty good fraction of that volume is in salts and electrodes, so you've got maybe a third or less that's solvent, and it's typically encased in sturdy plastic.

Personally, I wouldn't worry about an AA battery in a bar-mounted bike light. If you had a battery system the size of my old lead-acid battery -- 3 cells about the size of a D cell -- hanging from the bike frame in a nylon bag, I might be concerned. If you're uncomfortable with even this level of risk, you might want to see if you can still find a nickel metal hydride lighting system.

colleen c

I would not worry too much about those Lithium Ion multiple battery pack if it is just in storage mounted on the bike or while being use. They pretty much safe unless you drop, smash or something like that. Charging them worries me much more being they are so sensitive. That being said does make one wonder just how safe it is to be having these high power cell being charge while up in the air of the friendly sky. The battery in the car does requires special needs because of the fear of what might happen during a collision. The battery might get smash and short out or something like that.

I think those Boeing 787 have Carbon Fiber as part of the "State of the Art" design in them. So I guessing your title of your post somehow relate to this fact

zacster

Yes Colleen, that was my point. I think we need a tongue-in-cheek icon or something. I wasn't serious about the bike question, but put that together in the air? IDK, it doesn't sound like a great combination. But then again, jet fuel burns too...

unterhausen

depends on the chemistry, turns out saying liion isn't all that specific. Found this about cars vs. Boeing

superfred

Yes electric car batteries can catch fire. But gasoline cars burn all the time and we don't see people making a huge fuss over them in the news. Back in the day when internal combustion was making headway against steam and electric cars, the electric car companies took out ads in newspapers denigrating the dangers of the "Internal Explosion Engine".

Looigi

One difference with Li batteries is that they can be their own ignition source. Gas, diesel, jet fuel won't ignite by themselves.

cyccommute 

Although it would depend on several factors, carbon fiber as used in cars, planes, bikes or parts isn't particularly flammable. The resins that the fiber is impregnated with can withstand very high temperatures and, in some cases, are self-extinquishing. Don't forget that carbon fiber is being use in high end, high performance cars as brake discs. There are many more things to worry about in a fire in the cabin of a carbon fiber airplane than the flammability of the carbon fiber structural materials.

cyccommute 

Diesel and jet fuel require a lot of heat to get them burning and they don't burn all that well as an open flame...kind of cold.

Gasoline, on the other hand, has a flash point of around -45F. While it won't ignite on it's own, with that low a flash point it doesn't need much help.

Burton

LOL Yup - likewise, about the only thing the carbon fiber used in aircraft has in common with the carbon fiber used in bicycles is the name!

Looigi

What's the differences, specifically?

Burton

The biggest 'specific' difference is that aerospace grade carbon fiber (both the graphite fibre and the bonding polymer) is a controlled substance produced by a limited number of companies.

Its pretty common knowledge that most carbon fiber bicycles are produced in China in specialty plants set up with state-of-the-art manufacturing facilities. That doesn't mean they use - or can even get, aerospace grade carbon fiber. Some things aren't general knowlegde, but ocassionally little hints come to the surface.

https://beta-www.bis.doc.gov/index.ph...xport-to-china

dougmc

The 787's problems aren't related to carbon fiber as far as I know. As for lithium ion problems, well, your cell phone, laptop and tablet all probably run on them too.

And really, any fire that would damage carbon fiber would also damage aluminium. Aluminium can burn too, you know (though it does have to get really hot.)

I wouldn't worry too much about them.

turbo1889

Currently the safest common Lithium battery technology is LiFePO4 cells. The energy density isn't as high but the chemical compound is very stable (mainly due to the iron content) and it takes an incredible amount of heat to break the compound and liberate the Lithium so it can cause all kinds of problems.

Apparently Boeing (not my favorite group of people, they are one of the companies that is the butt of some engineer jokes) have been living under a rock somewhere and haven't figured that out and used one of the most volatile and dangerous chemistry available (there are about five different Lithium battery chemistry variations and LiCoO2 is like the second from the worst for safety).

Stuff like this really burns those of us who do e-bike builds (bikes with both pedals and an electric motor) since a lot of the batteries we use we have trouble getting because the airlines refuse to ship them by air freight so they can only go by land or sea specifically because several airplanes and crews have already been lost hauling freight that contained large size lithium based batteries. So you can imagine how it brushes our fir the wrong way when some stupid bunch of stuck of idiot geeks that think they know it all put a significantly bigger (and thus more dangerous) and one of the more dangerous chemistry batteries that even us e-bike guys have started to switch to better alternatives built right into the airplanes themselves and they have a gall to twiddle their thumbs and act like their are all surprised when the proverbial turd hits the proverbial fan that everyone warned them about and they looked down their noses at the warnings. I doubt the pilot and cargo crew unions are really impressed either. Personally I have absolutely no sympathy for Bowing, their 787 plane, or the know it all punks they have working their who put the thing together.

My sympathies are for the poor crews and ground folks who have to deal with this kind of stupidity. For only a weight penalty of about 25% extra on the batteries they could have used an alternate chemistry which have provided just as much power with the added bonus of a slightly more stable power curve and would have been several times safer and the batteries would have had to get hotter then what would be needed to melt the plastic cases of the batteries before the chemistry would break down to liberate the Lithium so it could cause problems.

But no those punks at Boeing wouldn’t think of doing that, their smarter then that, they know better.

Burton

I don't think this was ever started as a serious thread and think it would be better to keep it on the light side.

Personally I don't think all the prople at Boeing are idiots - they would never have hotten so large if they were. Truth is that many aircraft components are jobbed out to specialized companies - things like landing gear, APU's, engines .... In this case the batteries, battery charger and electrical system were designed and manufactured by three different aerospace companies - Yuasa (Japanese), Thales (French) and Securaplane Technologies Inc (American).

If there's a joke in there somewhere its more like the story of the blind men describing what an elephant is like based on what part they touched.

Wil Davis

Is there enough oxygen at 38000 feet for you to worry about your CF bike spontaneously bursting into flame?

- Wil