# What can batteries do in my pocket? Or: Help! My crotch is on fire! **URL:** \ **Category:** In My Humble Opinion\ **Created:** [April 17, 2004, 4:04am UTC](https://boards.straightdope.com/t/what-can-batteries-do-in-my-pocket-or-help-my-crotch-is-on-fire/240482 "2004-04-17T04:04:32Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![jackelope](https://avatars.discourse-cdn.com/v4/letter/j/a6a055/32.png) [@jackelope](https://boards.straightdope.com/u/jackelope)\ **Post date:** [April 17, 2004, 4:04am UTC](https://boards.straightdope.com/t/what-can-batteries-do-in-my-pocket-or-help-my-crotch-is-on-fire/240482/1 "2004-04-17T04:04:32Z")
I’m a photography junkie, and always carry a digital camera with me. Since the batteries always seem to die just when the UFO lands in my backyard, I’ve taken to carrying a couple spare AA batteries in my pocket. Tonight I was at work when I thought I felt something poking my outer thigh. I felt the area with my hand, and realized that I wasn’t being poked; the area was HOT. So hot that it hurt my fingers to touch it. As a card-carrying, dues-paying member of the Hypochondriacs’ Club, my first thought was, of course, “Holy crap! It’s [spontaneous human combustion](http://www.straightdope.com/classics/a1_205b.html)! I’m going to burn to a pile of waxy ashes, leaving objects in my immediate vicinity uncharred!” Calming down somewhat, I thought of the [little flashlight](http://www.brookstone.com/shop/product.asp?product_code=MICROBEAM&search_type=search&search_words=keychain#) that’s on my keychain; I took it out of my pocket and turned it on and pressed it against my finger, but it didn’t seem to produce any heat at all, although my keychain was also hot enough to brand flesh. Also, my leg still seemed to be on fire. Emptying my pocket hurriedly, I yanked out the two AA batteries (the ones slight shorter and thinner than your pinky finger). It was the batteries! Those suckers were HOT: so hot that I couldn’t keep them in my hand for more than a moment. I went to the bathroom and washed my hands with soap and water, then used a paper towel to pick up the batteries, which were still hot but appeared to be cooling off a bit. Within a few minutes they’d returned to room temperature. So what happened? I have a two theories: (1) As I understand the inner workings of alkaline batteries (which is to say, “extremely vaguely”), they contain two separate compartments, one containing a very strong base and one containing something else, possibly lemonade. I suppose these two substances combine in small, measured amounts and release electricity, uh, somehow. So maybe the batteries ruptured inside and the alkaline stuff and the lemonade all combined at once, releasing a lot of energy that turned to heat since there was no game of Electronic Battleship handy for it to power. This seems unlikely, mainly because both batteries appeared to be heating up at the same time. On the other hand, I’ve had trouble with all the batteries I’ve used out of this ten-pack so far; maybe I got a bad batch. (2) Now, I also had some coins in my pocket as well as the metal keychain. My second theory is this: The batteries and the coins and the keychain all somehow managed to align themselves in my pocket in such a way as to create a complete circuit, anode to cathode and cathode to anode, in what electricians refer to as a “Tesla Sixty-Nine.” The circuit would then have released all the energy in the batteries quickly, and the resistance in the connecting metal objects would have turned the electricity to heat, which in turn seared a bit of flesh uncomfortably close to my Little Buddy. This one seems more likely, except for the fact that I just have a hard time imagining everything lining up that way so perfectly and staying there in my pocket long enough to heat up that much. Anyone have suggestions as to what might have happened here? Is there a third possibility that I haven’t even thought of? One more detail: I couldn’t see anything leaking from the batteries, as I could in my prior IMHO thread, [Is this a chemical burn? (Answers needed ASAP)](http://boards.straightdope.com/sdmb/showthread.php?t=226582). (Yes, I seem to have bad luck with batteries of late.) Your thoughts? ---
**Author:** ![Gunslinger](https://avatars.discourse-cdn.com/v4/letter/g/4491bb/32.png) [@Gunslinger](https://boards.straightdope.com/u/Gunslinger)\ **Post date:** [April 17, 2004, 4:48am UTC](https://boards.straightdope.com/t/what-can-batteries-do-in-my-pocket-or-help-my-crotch-is-on-fire/240482/2 "2004-04-17T04:48:03Z")
Definitely (2). The key and/or coins in your pocket shorted the batteries together and heated everything up. Amusing anecdote on the dangers of pocketing batteries: One time my uncle, who works in construction, stuck a spare cordless drill battery (y’know, the 9.6v ones that are about 10x2x1 inches) in his nail apron before going up on the roof. Unfortunately, the pocket he stuck it in had nails in it, so the battery shorted, overheated and actually set the apron on fire. He managed to get it off before the fire spread to his clothes. ---
**Author:** ![Zabali\_Clawbane](https://avatars.discourse-cdn.com/v4/letter/z/ecd19e/32.png) [@Zabali\_Clawbane](https://boards.straightdope.com/u/Zabali_Clawbane)\ **Post date:** [April 17, 2004, 5:05am UTC](https://boards.straightdope.com/t/what-can-batteries-do-in-my-pocket-or-help-my-crotch-is-on-fire/240482/3 "2004-04-17T05:05:28Z")
So, instead of pocketing them “bare” put each one in a plastic ziploc baggie, wrap them up, and rubberband them? If you do it correctly, you don’t end up with a huge wad. Put one baggie inside the other, then roll/fold them, then bind them. Better than risking catching your pants on fire. 😉 ---
**Author:** ![jackelope](https://avatars.discourse-cdn.com/v4/letter/j/a6a055/32.png) [@jackelope](https://boards.straightdope.com/u/jackelope)\ **Post date:** [April 17, 2004, 5:20am UTC](https://boards.straightdope.com/t/what-can-batteries-do-in-my-pocket-or-help-my-crotch-is-on-fire/240482/4 "2004-04-17T05:20:05Z")
> [@Zabali\_Clawbane](#): > > So, instead of pocketing them “bare” put each one in a plastic ziploc baggie, wrap them up, and rubberband them? If you do it correctly, you don’t end up with a huge wad. Put one baggie inside the other, then roll/fold them, then bind them. Better than risking catching your pants on fire. 😉 Or I suppose I could just put one in each pocket. ---
**Author:** ![Krisfer\_the\_Cat](https://avatars.discourse-cdn.com/v4/letter/k/5f9b8f/32.png) [@Krisfer\_the\_Cat](https://boards.straightdope.com/u/Krisfer_the_Cat)\ **Post date:** [April 17, 2004, 5:21am UTC](https://boards.straightdope.com/t/what-can-batteries-do-in-my-pocket-or-help-my-crotch-is-on-fire/240482/5 "2004-04-17T05:21:48Z")
YIKES! Another photography buff here! Thanks for trying this experiment and getting back to us with the results. 😃 ---
**Author:** ![lieu](https://avatars.discourse-cdn.com/v4/letter/l/c2a13f/32.png) [@lieu](https://boards.straightdope.com/u/lieu)\ **Post date:** [April 17, 2004, 5:45am UTC](https://boards.straightdope.com/t/what-can-batteries-do-in-my-pocket-or-help-my-crotch-is-on-fire/240482/6 "2004-04-17T05:45:15Z")
What a great way to let a girl know you’re interested… having your pants burst into flames. ---
**Author:** ![Really\_Not\_All\_That\_Bright](https://avatars.discourse-cdn.com/v4/letter/r/e8c25b/32.png) [@Really\_Not\_All\_That\_Bright](https://boards.straightdope.com/u/Really_Not_All_That_Bright)\ **Post date:** [April 17, 2004, 6:37am UTC](https://boards.straightdope.com/t/what-can-batteries-do-in-my-pocket-or-help-my-crotch-is-on-fire/240482/7 "2004-04-17T06:37:54Z")
> [@jackelope](#): > > Or I suppose I could just put one in each pocket. Bastard. I just squirted Snapple all over the keyboard- _through my nose_. ---
**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\ **Post date:** [April 17, 2004, 6:47am UTC](https://boards.straightdope.com/t/what-can-batteries-do-in-my-pocket-or-help-my-crotch-is-on-fire/240482/8 "2004-04-17T06:47:46Z")
> [@](#): > > The batteries and the coins and the keychain all somehow managed to align themselves in my pocket in such a way as to create a complete circuit, anode to cathode and cathode to anode, in what electricians refer to as a “Tesla Sixty-Nine.” I’m sure my neighbors are wondering what’s so funny, and the dog is looking at me strangely. I knew a guy who, about 20 years ago, got burned to the point of scarring from a 9-volt “transistor” batter and the change in his pocket. ---
**Author:** ![Tikki](https://avatars.discourse-cdn.com/v4/letter/t/5daacb/32.png) [@Tikki](https://boards.straightdope.com/u/Tikki)\ **Post date:** [April 17, 2004, 6:49am UTC](https://boards.straightdope.com/t/what-can-batteries-do-in-my-pocket-or-help-my-crotch-is-on-fire/240482/9 "2004-04-17T06:49:38Z")
One time at work, I had to insert a bunch of batteries into some doo-dads we’d made. The batteries were the 9 volt kind that have both contacts on one end, and rather than being in bulk, they all came in their own little cardboard and plastic packages like you’d get in the store. Let me tell you that opening one or two of those is not a problem but opening several dozen is a hassle and hard on your hands. So anyway, I decided to open them all at once and get it over with. I dumped the batteries in a small box as I got them extricated. Then I started to insert them into the doo-dads. I picked up a battery and thought, “Gee, this feels awful warm.” I rummaged around and found that some of the other batteries also felt warm. Warm to hot, but not hot hot. Of course, I realized that the batteries, being jumbled together as they were, had been playing touchy-feely with one anothers’ contacts. I stood them all on end and continued inserting them into the doo-dads. So, yes, in your scenario, I also go with Theory #2, which brings me to: > [@jackelope](#): > > This one seems more likely, except for the fact that I just have a hard time imagining everything lining up that way so perfectly and staying there in my pocket long enough to heat up that much. One time I put my purse on the conveyor for the x-ray machine at the airport. At the other end, a nice security person asked if she could open my purse and look inside. Of course, this is the kind of person you don’t say ‘no’ to when she asks that kind of question, but, hey, I didn’t mind anyway. Especially since I could see on the monitor the shadowy contents of my x-rayed purse. Those random contents had managed to organize themselves into the exact profile of a pistol! Go figure. Fortunately, this was way before 9/11 and I wasn’t descended upon by a horde of overzealous real-gun-weilding homeland security types. So, I’m not really surprised that a bunch of metal stuff in your pocket got together with your batteries and decided to play a little trick on you. Ordinary, everyday things can be sneaky that way. ---
**Author:** ![SSgtBaloo](https://avatars.discourse-cdn.com/v4/letter/s/ac91a4/32.png) [@SSgtBaloo](https://boards.straightdope.com/u/SSgtBaloo)\ **Post date:** [April 17, 2004, 7:22am UTC](https://boards.straightdope.com/t/what-can-batteries-do-in-my-pocket-or-help-my-crotch-is-on-fire/240482/10 "2004-04-17T07:22:02Z")
Definitely sounds like some sort of connection between all the metallic objects in your pocket and the rapid discharge (and heating) of the batteries. When I was stationed At Fairchild AFB, it could get very, _very_ cold. working outdoors in sub-freezing temperatures, you had to do something to keep your hands warm. Gloves interfered with the ability to perform dextrous tasks with cold steel tools. Some guys figured out that if you took two nine-volt batteries (the ones with the snap-click terminals) and clipped them together, they would get WARM very quickly. We’d each go to the flightline supply point, get four 9v batteries, clip them together, and stick a pair in the right and left pockets of out parkas. When our hands started to go numb from the cold, we’d just (carefully!) shove our hands in our pockets until they were warm again, and continue working.[/hijack] That bit about individually wrapping each battery sounds like good advice, especially since you’re carrying them so close to Mr. Happy. –SSgtBaloo ---
**Author:** ![Jman](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jman/32/4416_2.png) [@Jman](https://boards.straightdope.com/u/Jman)\ **Post date:** [April 17, 2004, 7:24am UTC](https://boards.straightdope.com/t/what-can-batteries-do-in-my-pocket-or-help-my-crotch-is-on-fire/240482/11 "2004-04-17T07:24:25Z")
First of all, for the baggie idea: it’s not necessary. The reason it heated up so fast is because the complete circuit was made by the keychain…with very, very low resistance (it’s just metal), which means that a buttload of current was flowing through the metal. You can experiment by holding a piece of wire on a battery with your fingers (anode to cathode)…it gets hot REALLY fast. However, There is essentially no possible way to align 4 batteries such that they will complete a circuit on their own… So, to sum up: just carry the batteries by themselves in your pocket, with no other metal items, and you’ll be fine. ---
**Author:** ![jdc](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@jdc](https://boards.straightdope.com/u/jdc)\ **Post date:** [April 18, 2004, 2:15am UTC](https://boards.straightdope.com/t/what-can-batteries-do-in-my-pocket-or-help-my-crotch-is-on-fire/240482/12 "2004-04-18T02:15:20Z")
Sprinkle some strike anywhere matches into your pocket to cushion the batteries and prevent them from shorting out. ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [April 18, 2004, 2:34am UTC](https://boards.straightdope.com/t/what-can-batteries-do-in-my-pocket-or-help-my-crotch-is-on-fire/240482/13 "2004-04-18T02:34:14Z")
> [@Jman](#): > > However, There is essentially no possible way to align 4 batteries such that they will complete a circuit on their own… Well, I can do it with just 2 cells. Have the negative of one bridge the positive and the nearby negative rim of the other. For historical reasons, the jacket of the standard tubular cells covers the bottom, sides and rim of the top. I have owned penlight flashlights that have relied on the top rim for contact with -. Sometimes there is a coating to cover those, but you can’t really trust them… Which gets me into my recent “oops” and battery shorting. I was rebuilding a LiIon battery pack last weekend, just finished soldering it all together and was trying to force them all back into the plastic holder when I noticed… a heck of a lot of heat coming off one of them. I quickly started bending contacts apart and such. One of the bands across the + of a pair of cells had shorted with the - of one of them. There’s a plastic wrapping around it and I tried to be careful soldering, but apparently the insulation hadn’t held up during the packing. I carry/store cells in plastic bags with all aligned in the same direction and stuffed parallel to each other. No end to end allowed. Got lucky, no burns, fires or permanent damage to the cell. ---
**Author:** ![Zabali\_Clawbane](https://avatars.discourse-cdn.com/v4/letter/z/ecd19e/32.png) [@Zabali\_Clawbane](https://boards.straightdope.com/u/Zabali_Clawbane)\ **Post date:** [April 18, 2004, 2:54am UTC](https://boards.straightdope.com/t/what-can-batteries-do-in-my-pocket-or-help-my-crotch-is-on-fire/240482/14 "2004-04-18T02:54:20Z")
> [@ftg](#): > > Well, I can do it with just 2 cells. Have the negative of one bridge the positive and the nearby negative rim of the other. \ I carry/store cells in plastic bags with all aligned in the same direction and stuffed parallel to each other. No end to end allowed. This method is what I was trying to communicate, albeit poorly. Find some way to keep them from touching at all, so you don’t risk it. Baggies, or something else, but keep the batteries seperated/insulated so they can’t possibly touch. After all, it would be annoying if they’d drained each other a bit, but not caught your pants on fire, wouldn’t it? ---
**Author:** ![Mirror\_Image\_egamI\_rorriM](https://avatars.discourse-cdn.com/v4/letter/m/e56c9b/32.png) [@Mirror\_Image\_egamI\_rorriM](https://boards.straightdope.com/u/Mirror_Image_egamI_rorriM)\ **Post date:** [April 18, 2004, 5:16am UTC](https://boards.straightdope.com/t/what-can-batteries-do-in-my-pocket-or-help-my-crotch-is-on-fire/240482/15 "2004-04-18T05:16:04Z")
I’ve seen this happen before. One morning, in Psychology class, the teacher was blathering on, as usual, I was doing some other homework, as usual, and Buford was asleep at his desk, as usual. All of a sudden, Buford sits bolt uprigth and starts frantically smacking his thigh. Cursing under his breath, he starts pulling crap out of his pocket…including two batteries and a keychain. I was a bit worried, because I had a pair of the exact same type of batteries in my bag, but mine weren’t stored with any metal. Of course, I didn’t know what caused Buford’s batteries to suddenly heat up, so I took mine out of my bag and kept them in my locker. But it was pretty funny seeing Buford go crazy like that.