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Why a Dead Alkaline Battery Bounces [video] (youtube.com)
289 points by kissgyorgy on Sept 5, 2014 | hide | past | web | favorite | 51 comments

I think one of the bits I liked most was "Romeo (Retired Old Men Eating Out) Club" - looking at its website it seems like quite a large thing over there. I know that my Grandma goes to something similar (restricted to just tea and bingo), but it makes me wonder if a similar organisation exists in the UK; a lot of the older folk I know just aren't very social any more, simply due to the fact that their social groups have died off or are spread out and have restricted travel options. Social interaction seems such a huge part of our existence to be missing for any individual (unless that's what they want of course).

Again, anecdotally; I've found amongst the older folks that those engaged in discussion and interaction keep their wits about them longer/easier than those bound by isolation.

Anyway, enough babbling on - time to go do some research.

One excellent organization is U3A http://www.u3a.org.uk/ My father runs one of their groups that specializes in studying geology, and they regularly have a hundred people turn up to the seminars they run. Science and social go well together when you've lots of free time.

My father also runs one of these to help people learn Photoshop (mainly for editing family photos). It's surprising the topics that can be learned though these groups

My grandmother runs a (quite large) group that provides a similar type of community for retired women over 65. It's a really interesting idea: they're all very smart and do a lot of interesting stuff. Most memorably they gave speeches in the Connecticut state senate advocating the right to euthanasia for terminally ill people of sound mind.

They could go further with the experiment to check if a material of which the battery content is composed matters or if the stiffness of the content is the only important factor.

They could for example check how bounciness changes when a battery is filled with a gel-like substance which could then be frozen.

Here is the transcript if you don't like watching the video http://bit.ly/1uD31Uz

It's interesting to me that using the height of the bounce against the ground for estimating the spring constant is worse than using the height of the bounce against the battery.

I don't really agree with that part of the test setup. The mass and springiness of the battery versus the slug dropped mask the fact that this is a double spring setup, there is also still the bottom of the battery contacting the base it all sits on so you can expect some of the bounce to be transferred to the battery which would not jump a whole lot. So at a minimum there would have to be a hard connection (clamped or glued in place or something like that) between the base and the battery to compensate for that.

What would the inside of a recharged battery look like I wonder.

It's not the same technology and I wouldn't recommend tearing a lithium battery apart to look inside. Actually, I wouldn't recommend tearing apart any kind of batteries, lots of nasty stuff inside.

You can find plenty of videos on youtube showing you the process, for instance: https://www.youtube.com/watch?v=BliWUHSOalU

After watching that it made me think that lithium batteries could be turned into a weapon on a plane by terrorists.

Assuming that they are that easy to accidentally short them out.

Should they not be a banned from being taken in the cabin?

They aren't really that easy to weaponize, at least not any more. The earliest kinds of Lithium cells actually contained elemental lithium, and could easily cause fire or explosion under certain conditions. Think the Dell laptop fire batteries.

Lithium _Ion_ batteries produced today are newer designs which use an intercalated Lithium compound (usually with Cobalt, Iron or Manganese) which greatly improves the stability of the battery while under stress. Further to that, pressure venting is almost always incorporated into the canister enclosing the cell, allowing it to depressurize in a safe manner similar to capacitors.

That's not to say they are totally safe - all batteries require a great deal of care and not all Lithium batteries incorporate these safety features. The pouch cells used in RC aircraft, for example can catch fire fairly easily due to their lack of a strong outer shell, their extreme power density and lack of any protection circuitry. These are heavily regulated and you would not be allowed to take them in your carry-on, and all Lithium Ion batteries over a certain Wh rating are similarly controlled.

> [RC pouch cells] are heavily regulated and you would not be allowed to take them in your carry-on

Speaking at least for Canadian airlines, you're incorrect - I asked ahead, and was told that I could bring them, but _must_ have them in my carry on. (and protect the connectors, etc.)

It's probably not banned because someone who could take over a plane with a lithium battery could take over a plane without a lithium battery.

Batteries above a certain capacity are not allowed.


But someone who could take over a plane with a nail clipper could probably manage without it, too.

And the TSA allows nail clippers in the cabin.

Any idiot could use one to set a plane on fire.

What makes you think banning in-cabin items has anything to do with actually making air planes more secure?

> After watching that it made me think that lithium batteries could be turned into a weapon

Lithium batteries have vents, so they don't explode they just "phhuut".

Vents can be blocked if you are trying to make it explode . . .

Yup. Also, don't forget about what small amounts of Mercury https://www.youtube.com/watch?v=Z7Ilxsu-JlY

or Gallium https://www.youtube.com/watch?v=Z7Ilxsu-JlY

could do. Happy flying!

The USPS has already banned shipment of lithium batteries overseas because of suspicions of battery fires in flight causing cargo jet crashes. When it was first created, the ban included devices as well as just solo batteries but it looks like that has been loosened.

> After watching that it made me think that lithium batteries could be turned into a weapon on a plane by terrorists.

They can be: https://www.youtube.com/watch?v=CH6GpXAXmx8

The funny thing is that in the US you're not allowed to have loose lithium batteries in your checked baggage, but you can carry them on the plane.

If the battery spontaneously combusts in the hold, you have a serious problem. The fire will be quite large before anyone knows about it. If your laptop catches fire in the cabin, you'll probably scream immediately, and they have burn proof fire bags to shove the laptop into.

Many airlines also wont allow shipments of lithium or things containing lithium batteries on passenger flights. Apparently they have a habit of spontaneous combustion. So shipments of iphones have to be specially packaged and sent on cargo flights.

They'd probably ban them if people didn't want to use laptops and phones.

The method has even been patented! http://www.google.co.uk/patents/US5567541

The patent was drafted very generally, but seems to focus on the volume (rather than elasticity) of the internal components. OTOH, it would be great if it were even more generally drafted, since its priority date is in 1995. 1995+17 = 2012, so the world is now wide open for innovation in this area, unimpeded by patents (IANAL).

Probably not the best idea to open a battery without gloves and a mask (though lithium batteries are worse in terms of gases).

Still very interesting to see the electrolyte though.

The quantity and variety of things that I've opened up during my lifetime without 'gloves and a mask' would probably scare you very much. The worst mistake I made to date is grinding off the top of a BLY90 as a kid before I knew what a MSDS is. So far so good, I think these folks will be fine as long as they wash their hands afterwards before eating, cleaning up after you've dropped a fluorescent tube is probably a lot more dangerous than this.

Don't go and turn anything into a fine powder!

Probably the most risky thing they did here was cutting up the batteries with a hacksaw which will create a bit of sawdust composed of metal and some electrolyte. But that's pretty easy to get rid of and won't become airborne. Using a grinder for the same job would be much more dangerous.

As to what people would play with without "gloves and a mask":


"After Slotin's accident, hands-on criticality experiments were stopped, and remote-control machines were designed by Schreiber, one of the survivors, to perform such experiments with all personnel at a quarter mile distance." Note: "After"... so what was the situation before?...

They would raise and lower the top half of the core with their bare hands, a screwdriver, and lots of shims. Literally hands-on criticality experiments.

BLY90: an RF power transistor.

MSDS: material safety data sheet.

Just what is it that's inside the BLY90 that's so bad?

For some reason, it upsets me that he refers to spent / empty / used batteries as "bad", as if they were faulty.

"Bad" is what I used growing up. I think it's by analogy to food--you would say that food has "gone bad" after a while. Similarly with batteries. You might also ask "are these batteries (still) any good?" to question not their quality in general, but their state.

It's almost certainly a regional thing.

He managed avoid the "flat" vs. "dead" controversy by making up a new convention altogether.

I think "consumed" would be most appropriate.

I'd say "depleted" but we're all missing the point.

Url changed from http://lifehacker.com/test-if-your-batteries-are-dead-by-dro..., which points to this.

Due to a Feedly bug (I think), this actually makes it much harder for Feedly users to comment. When an HN story links directly to YouTube, Feedly omits the link to the comments that is normally present in its display of HN RSS.

I think this is a Feedly problem, not an HN RSS problem, because it works fine in Digg Reader.

I'm curious if others have noticed this. I believe when someone posted a poll question here asking what RSS readers people switched to after Google Reader went away, Feedly was one of the most popular.

I'm not saying this was the wrong move, but one drawback of the change is that I'm not in a setting where I can watch a video with sound right now, so the writeup is much more helpful than the video to me.

On the other hand, as long as you make a comment like this when you change a link, it alleviates the problem pretty well.

Aha! It is very unusual to see a youtube link not just on the front page, but at the top spot of it.

Electrons change things, yo™ :)

Meh, I don't care if I lose more stupid fucking Hacker News points, but I can't understand why I would have been down voted for this comment.

It has electrolytes!

It's what plants crave.

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