9v battery explosion

November 2, 2006 4:48 PM

Can anyone tell me why a 9v battery would explode? Description of the event...

Just a while ago I heard what sounded like a .22 being fired and was sprayed with warm stuff. At first I thought I had been shot but upon inspection it turned out to be a 9v battery that was sitting on a work bench behind me. It's the tiny rectangular kind with the terminals next to each other (the kind you stuck your tongue on when you were a kid).

It wasn't touching anything and the "warm stuff" was gray sticky powder. The part that blew out is opposite the terminals.

Any ideas? This kinda freaked me out.

posted by snsranch to science & nature (11 comments total)

9 volt batteries are actually made up of 6 1.5 volt mini-cells (they are occasionally sold separately as AAAAs). At a guess, I would say that one of these internal cells became damaged and corroded through to one of it's neighbors. Why that would be explosive I'll leave to the experts better than I.

Just out of curiosity, was it a rechargeable 9 volt? Or maybe one of the newer styled High Output batteries that have become popular in the last couple of years? They tend to use more volatile chemicals like lithium-ion.
posted by quin at 5:07 PM on November 2, 2006

Not really an answer to your question, but Popular Science recently recanted a project involving opening a 9v battery.

Although experts advised us that it is not normally dangerous, and we tried the project ourselves without incident, it has come to our attention that in rare instances, the cells inside the battery can “vent” or rupture, potentially exposing the handler to the chemicals inside.

Still no idea why it would explode, however.
posted by Terminal Verbosity at 5:20 PM on November 2, 2006

It's a duracell pile alcaline, and, yep, one of the small cells popped out.
posted by snsranch at 5:20 PM on November 2, 2006

Had the battery been dropped or knocked about or treated roughly? I've had a D-cell get an internal short due to an overtight battery-clip causing the metal case of the cell to short the cell inside, so perhaps some kind of trauma can similarly result in a short of one of the cells inside a 9V.
Or it might just be a manufacturing defect.

At any rate, you can probably get a free replacement battery :-)
posted by -harlequin- at 5:25 PM on November 2, 2006

The same battery just popped again and it faintly smells of rotten eggs/sulfur. Actually not so faintly.
posted by snsranch at 5:45 PM on November 2, 2006

I dunno. That happens to my AA and AAA batteries all the time.
posted by schroedinger at 5:48 PM on November 2, 2006

The only time I've seen an electronic component explode was when I tried to soup up a walkie talkie with 12VDC instead of 9VDC. One of the capacitors inside exploded, and was enough to blow a hole in the circuit board and crack the walkie talkie case. I'm not sure whether the chemistry is similar but it makes me wonder if there was some sort of internal leakage in the battery that became a short circuit when the battery was propped in a certain position... upright, for example.

It would be interesting (maybe even relevant) to know what the brand of battery was, and if there was any expiration/manufacture date.
posted by rolypolyman at 6:22 PM on November 2, 2006

Is it cold there? Could the liquid inside the battery have frozen? I've seen soda cans explode before when freezing caused the liquid inside to expand.
posted by chrisamiller at 6:25 PM on November 2, 2006

duracell pile alcaline. I thought the battery was spent. It came from one of my kids R/C controllers. So yea, it was probably beaten up a bit.
posted by snsranch at 6:27 PM on November 2, 2006

It's difficult to say. I think there are multiple possible reasons for a battery to explode but this would usually be under load or due to damage or in extreme environments.

I'd keep it, take some pictures and write to Duracell. It might indicate a bad production run. If it still is exploding I wouldn't send it in the mail.
posted by chairface at 6:58 PM on November 2, 2006

I'd keep it, take some pictures and write to Duracell. It might indicate a bad production run. If it still is exploding I wouldn't send it in the mail.
posted by chairface

Yes, thanks, that's exactly what I'll do.
posted by snsranch at 7:51 PM on November 2, 2006