Bathroom scales just exploded !!

[MathWizard]

I was just doing some soldering, and I hear a seriously loud bang in the next room, louder than any capacitor or part I've heard blow up, closer to a gunshot. I though maybe it was the furnace, or my computer PSU, or the lithium battery in my MP3 player.

But it was a regular 1.5V AAA alkaline battery, 'ruwido' brand. It was in a cheap ebay, digital bathroom scales (they've worked fine for +10years).

The scales use 2xAAA batteries, and has auto off. I've never had any issue with it killing rechargeable batteries, so I can't say there was any shorting problem that might heat up a battery. But I went into the kitchen where the scales are, and there's a little pile of like carbon/charcoal looking type stuff on the floor, and the side of the battery split open like a sausage, and I can see some white cylinder inside.

And it's almost hot, IDK if it's still cooking, so I put it in a can outside. I used the scales today maybe 5-6hrs ago, the battery case looks a little dirty but otherwise ok.

But holy crap, that startled me, makes me realize I should get a fire extinguisher. I never knew regular batteries are sealed so tight, as to make such a bang. I don't remember buying these batteries, they might have been from a remote control I got somewhere. Lucky they weren't packed away.

[EEVblog]

Wow, first I've heard of that. Leaks, yeah, all the time, loud explosion? 

[amyk]

Wow, first I've heard of that. Leaks, yeah, all the time, loud explosion? 

The alkaline chemistry evolves hydrogen as it discharges. There is a hydrogen absorber (used to be mercury, but newer cells have something else), or maybe the cheap ones omit it entirely? Most of them aren't sealed well enough and just leak. The ones that are, will instead let go with a bang. There are many other accounts of this happening to the thin cylindrical cells found in some 9V batteries, but I've personally experienced the seal popping loudly, followed by leakage, after discharging AAs at a very high rate (near short-circuit conditions.)

[IanB]

Alkaline cells are either going to leak or explode. One way or another the pressure building up inside has to escape. Maybe enough people have been complaining about leakage that they have tried to seal them up really tightly and cause them to explode instead?

[Berni]

I seen a cell inside a 9V battery explode before.

But never seen anything like that happen to a AAA cell, let alone have it explode this violently. Dang

[EEVblog]

Wow, first I've heard of that. Leaks, yeah, all the time, loud explosion? 

The alkaline chemistry evolves hydrogen as it discharges. There is a hydrogen absorber (used to be mercury, but newer cells have something else), or maybe the cheap ones omit it entirely? Most of them aren't sealed well enough and just leak. The ones that are, will instead let go with a bang. There are many other accounts of this happening to the thin cylindrical cells found in some 9V batteries, but I've personally experienced the seal popping loudly, followed by leakage, after discharging AAs at a very high rate (near short-circuit conditions.)

Come to think of it I have seen 9V battiers that look like they have exploded violently

[Greybeard]

Photos please...
 

[Psi]

Alkaline cells are either going to leak or explode. One way or another the pressure building up inside has to escape. Maybe enough people have been complaining about leakage that they have tried to seal them up really tightly and cause them to explode instead?

 

[golden_labels]

How long before “Learn how to stop batteries from exploding!” on YouTube, with videos from south-east Asia showing people drilling holes in batteries?

The same style as:

(source unknown, found on “DrNO’s fun-site”)

[Stray Electron]

But it was a regular 1.5V AAA alkaline battery, 'ruwido' brand. It was in a cheap ebay, digital bathroom scales (they've worked fine for +10years).

The scales use 2xAAA batteries, and has auto off. I've never had any issue with it killing rechargeable batteries,

   So you were using an alkaline battery where you were supposed to use a rechargeable battery?   You've just discovered why you're not supposed to recharge alkaline batteries.  They evolve gas (and sometimes steam) when recharged and their metal can is an unvented, sealed container and it can burst when the pressure gets high enough.   Most rechargeable batteries have a vent or a plug that will blow out safely if their pressure gets too high (the batteries vent and some electrolyte escapes which is why you frequently find corrosion around rechargeable batteries).

   When you were a kid did you ever throw an unopened can of beans in the fire at camp?  The same thing will happen. 

[Doctorandus_P]

After reading the title of this thread, my first thought was:

Yo Mama   

[xrunner]

Photos please...

He must be teasing us. Who would post such a thread without pics? I mean an exploded bathroom scale has to be shown to the world! 

[CaptDon]

O.P. never claimed it was 'recharging' when it failed. Probably doesn't even have an external power pack recharge function. He only stated that rechargeable batteries seemed to work without any problem in the scale. There was a time period shortly after removing the mercury from alkaline batteries that they were still being sealed and sold as 'leakproof' which we all know is a joke with alkaline technology. During that time period alkaline batteries were known to burst right on the store shelves. It was a lesson learned and now they just leak and corrode right on the store shelves!! I have switched to the Ultimate Lithium batteries for my wireless mics and dive lights. Sadly, very very costly and you don't get double the watthours for double the cost!!! Knowing they don't leak or explode is good peace of mind but absolutely don't try to recharge an ultimate lithium eveready battery. I did just for the hell of it. It doesn't work and they get very hot as they internally self destruct and become totally unusable.

[themadhippy]

[Greybeard]

It wasn't me, it was the bathroom scales...
 

[Messtechniker]

Just a moment ago an expired LR44 exploded with quite a bang.
See pic.
It even blew the golden lid off!
It had been bulging before. So be warned.


Never happened to me in the say 50 yrs before.

[MathWizard]

Yeah I'll try and take a picture with my Andostar microscope, I threw out the one that didn't blow-up tho, so no taking it apart. I'm pretty sure they came with the used stereo I fixed up this winter.

I haven't tried the scales yet, I'm going to check if the negative spring clip can ever touch the other batteries positive. Besides that, it's probably just some weird brand, or some defect, and it was a ticking time bomb.

It didn't flip the scales over, but they moved some for sure. I've had something like a 22uF cap blowup in my face, and send the can flying, but this battery was way louder. There was a proper bass note to it, some combo of the battery hitting the floor, and the scales jumping, but it only sounded like one event, so they didn't jump very high.

I didn't smell anything in the air at all either.

[MathWizard]

Here's some pic's, it split right along the side, I never tried to take it apart. I'll check what metal it might be, but it would take a lot of pressure top do that. I can't say I saw any shards of metal on the floor, but imagine having that in a walkie-talkie when it blew up !!

It seems I can't upload them at once, they are all ~3MB. 1st I couldn't find the micro-SD card, then I couldn't find the USB cable.

[MathWizard]

only 2 files fit

[MathWizard]

last one

[MathWizard]

It looks like Aluminum, but it can't be, it's highly magnetic. I didn't have the plastic cover over the batteries, and the scales are only battery powered.

You can see scratches on the plastic, with the black stuff in them, I never scratched inside the case with anything, so it must have been the battery bursting.

[amyk]

The case is made of steel. The black stuff is likely manganese dioxide.

[coppercone2]

a normal alkaline battery has a vent feature on it. A over pressure vent that makes it leak electrolyte rather then exploding. At least so it does not rupture violently.

Sleezy manufacturers get rid of this vent, which allows the cell to explode. Of course, it won't leak until it does. The idea is not to get sprayed with hot electrolyte. Its supposed to have a fairly low pressure burst disk type feature.

One engineering approach is to try to get rid of gas build up with chemistry, the off brand approach is to make a bomb. I think thats why you see zinc carbon low cost cells included with some low cost products, rather then off brand similar capacity to name brand alkaline, which don't have the chemical engineering used to try to make them reliable with a burst disk. They don't want the liability (its bad for your face)

Or it could have been a QC over sight (i.e. vent not formed properly, wrong part used, obstruction (bad crimp or debris), I imagine they might have little room to work on in AAA batteries, so if you over crimp, you could say... crush the 'burst slot' or whatever feature you have on the battery, greatly increasing the 'vent pressure'.



The 9V battery uses AAAA cells or very similar. You hardly have any room in there for anything, meaning even if you engineer it right, your manufacturing needs to be precise. No worn dies, jigs, alignment features, etc. Combine the precision requirement with low cost high volume and suddenly it turns out you just can't make the thing as cheap as you think you can.  Then combine that with the requirements for maintaining your electroplating baths and other cell manufacturing shit and you got extra gas being formed from corrosion

i imagine its a slew of tricks used to get it to not leak in the package when its stored 5 years past expiration date too in a warehouse before relabling


if you take a good look at the cell, you will see there is only one place to put a pressure vent. you have to be precise. It means putting money into manufacturing, regularly. It also means R&D inventions are very welcome to make this process easier.. I don't think the alkaline battery is anywhere near its full engineering potential for manufacturability and quality, as old as it is


and the 9V battery is a unique opportunity, to use grab bin of whatever AAAA is available. mystery enchilada. You might get 5 sticks of ground beef and 1 stick of off brand spam in your baking tray if someone feels like making a dollar

[Psi]

alkaline with vent = battery
alkaline without vent = pipebomb.

[bd139]

LR44's like to spontaneously explode. They go with quite a bang.

So a few years back it's the middle of the bloody night and there's this cracking great big bang come from my two youngest kids' bedroom. Rushed in there and can find no evidence of anything at all that has happened. They heard it and it woke them up and scared them. I heard it two rooms away.

After taking EVERYTHING to bits to work out what it was, I found the culprit. My middle one had an LED illuminated rubbery clear plastic llama she used as a night light. This had 3x LR44's in it. Turns out it one of them had exploded. It wasn't until I accidentally squeezed it when picking it up that hilariously smoke came out of the llama's arse and the culprit was identified. It took out the battery compartment entirely.