# Suicide by 9-volt battery. **URL:** \ **Category:** Factual Questions\ **Created:** [May 4, 2004, 3:32pm UTC](https://boards.straightdope.com/t/suicide-by-9-volt-battery/243473 "2004-05-04T15:32:03Z")\ **Posts on this page:** 15\ **Page:** 2
**Author:** ![alterego](https://avatars.discourse-cdn.com/v4/letter/a/6bbea6/32.png) [@alterego](https://boards.straightdope.com/u/alterego)\ **Post date:** [May 5, 2004, 8:11am UTC](https://boards.straightdope.com/t/suicide-by-9-volt-battery/243473/21 "2004-05-05T08:11:55Z")
How many volts would a battery need to have before touching it to your tongue made you kick the bucket? ---
**Author:** ![Inigo\_Montoya](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/inigo_montoya/32/124_2.png) [@Inigo\_Montoya](https://boards.straightdope.com/u/Inigo_Montoya)\ **Post date:** [May 5, 2004, 11:01am UTC](https://boards.straightdope.com/t/suicide-by-9-volt-battery/243473/22 "2004-05-05T11:01:35Z")
> [@alterego](#): > > How many volts would a battery need to have before touching it to your tongue made you kick the bucket? 9 volts’d do it if the amperage were high enough and if the electricity could adversely affect a vital organ like yer heart. To reach the heart from your tongue would require that this path have less resistance than any other available to the terminals on the battery. Basically, you’d have to touch one battery terminal to your tongue, and find some way to complete a circuit to the other by way of, say your feet (maybe you’re standing on a wire that leads to the other terminal). With the set up on a 9-volt, you could pass pretty much any amount of current accross the tongueflesh for as long as you could stand it with the only adverse effect being a partially cooked tongue. bleah! ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [May 5, 2004, 11:21am UTC](https://boards.straightdope.com/t/suicide-by-9-volt-battery/243473/23 "2004-05-05T11:21:30Z")
> [@Inigo Montoya](#): > > To reach the heart from your tongue would require that this path have less resistance than any other available to the terminals on the battery. Basically, you’d have to touch one battery terminal to your tongue, and find some way to complete a circuit to the other by way of, say your feet (maybe you’re standing on a wire that leads to the other terminal). Not really. It is true the current density will be greatest in the tongue between the terminals (all else being equal). But you should keep in mind that current really goes _everywhere_. To model the circuit, you would place a bunch of resistors wired parallel across the battery. The resistors with the lowest resistance would represent the locations in the body that are closest to the battery; the resistors with the highest resistance would represent the locations in the body that are farthest away from the battery. Again, all else being equal. Current flows through _all_ resistors, and the resistors with the highest resistance will have least current. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [May 5, 2004, 9:23pm UTC](https://boards.straightdope.com/t/suicide-by-9-volt-battery/243473/24 "2004-05-05T21:23:12Z")
Repeat after me, everyone: V = IR. This means that you can’t just say “nine volts is enough, if the current is high enough”, or “it’s the amps that kill you, not the volts”. Given a resistor and a voltage, the current is absolutely, completely determined. A low-voltage battery cannot produce a high current, unless the circuit has very low resistance. As for electrocution by multimeter, a multimeter in ohm mode does not generally put its full battery voltage across the terminals. The actual voltage used will be far lower, generally in the tenth of a volt range or less. This is not just for safety reasons, but for purposes of a more accurate measurement: Too much juice can heat up your element, which in turn can change the resistance. So I suspect that both the Navy story and the professor story are bunk. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [May 5, 2004, 9:30pm UTC](https://boards.straightdope.com/t/suicide-by-9-volt-battery/243473/25 "2004-05-05T21:30:31Z")
> [@Chronos](#): > > Repeat after me, everyone: V = IR. We know this. > [@"Chronos](#): > > This means that you can’t just say “nine volts is enough, if the current is high enough”… Sure you can. Saying “nine volts is enough, if the current is high enough” is exactly equivalent to saying “nine volts if enough, if the resistance is low enough”. Given any two terms of the Ohm’s Law equation, and any 7th grader can calculate the third. ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [May 5, 2004, 11:40pm UTC](https://boards.straightdope.com/t/suicide-by-9-volt-battery/243473/26 "2004-05-05T23:40:57Z")
**Chronos** : We covered this topic in excruciating detail in this thread: > **[Why don't I get shocked by batteries?](https://boards.straightdope.com/sdmb/showthread.php?t=161521)** > > Why don’t I get shocked when I touch the two contact ends of a battery simultaneously? Granted, I’ve only tried this with low-power consumer batteries like AA, C, D, 6v, etc. I don’t think I’ll try it on my car battery. I am not convinced an old Simpson VOM is incapable of killing someone if the conditions are “right.” This would include: 1. Breaking the skin, thus making the body resistance quite low. 2. Setting the meter to the highest ohms range. (My guess is that some of the old analog meters used a relatively high excitation voltage when measuring high resistance. This is because the current sensing circuitry wasn’t very sensitive, and the meter needed to produce a high voltage in order for its circuitry to sense the current.) At any rate, I think I have some old meters lying around here. I’ll check them out if I have time. ---
**Author:** ![LivingInThePast](https://avatars.discourse-cdn.com/v4/letter/l/e19b73/32.png) [@LivingInThePast](https://boards.straightdope.com/u/LivingInThePast)\ **Post date:** [May 6, 2004, 2:30am UTC](https://boards.straightdope.com/t/suicide-by-9-volt-battery/243473/27 "2004-05-06T02:30:08Z")
> [@FilmGeek](#): > > Any battery will get hot. > > And begin to smoke. > > And hurt. > > I heard. 😉 Yeah, if you manage to short the terminals. Which is very hard to do with a standard (say, AA) battery. But which is _very easy_ to do with a 9-V battery (speaking from experience here). :eek: ---
**Author:** ![LivingInThePast](https://avatars.discourse-cdn.com/v4/letter/l/e19b73/32.png) [@LivingInThePast](https://boards.straightdope.com/u/LivingInThePast)\ **Post date:** [May 6, 2004, 3:04am UTC](https://boards.straightdope.com/t/suicide-by-9-volt-battery/243473/28 "2004-05-06T03:04:24Z")
> [@Crafter\_Man](#): > > I am not convinced an old Simpson VOM is incapable of killing someone if the conditions are “right.” Well, a while spent searching the web found nothing on the topic, which is surprising. If it were an urban legend, you’d think it would be all over the place. Similarly, if it were true, you’d think it would be spread far and wide. The [Simpson Electric](http://www.simpsonelectric.com/) website does not mention this, either, and you can draw your own conclusions about that. Or you can email them from the link on their page and ask (but would they admit it if it were possible?) For those interested in weird electricity, I did find [this link](http://www.broadcast.net/pipermail/radio-tech/2001-April/003041.html). It and its following pages tell tales of woe caused by external high voltages, but it does involve a Simpson VOM. :dubious: ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [May 6, 2004, 3:13am UTC](https://boards.straightdope.com/t/suicide-by-9-volt-battery/243473/29 "2004-05-06T03:13:23Z")
You didn’t look very hard. The [Darwin Awards](http://darwinawards.com/darwin/darwin1999-50.html) has this very story, which is very similar to the one related by **Crafter\_Man** , though some details differ. ---
**Author:** ![LivingInThePast](https://avatars.discourse-cdn.com/v4/letter/l/e19b73/32.png) [@LivingInThePast](https://boards.straightdope.com/u/LivingInThePast)\ **Post date:** [May 6, 2004, 3:31am UTC](https://boards.straightdope.com/t/suicide-by-9-volt-battery/243473/30 "2004-05-06T03:31:31Z")
> [@Q.E.D.](#): > > You didn’t look very hard. The [Darwin Awards](http://darwinawards.com/darwin/darwin1999-50.html) has this very story, which is very similar to the one related by **Crafter\_Man** , though some details differ. Oh. :smack: Well, I wonder how someone safely measured the internal resistance of the human body as being 100 ohms? I don’t have time right now to search for that bit of info, but maybe later… :o \<- that’s a yawn, IMHO. ---
**Author:** ![AHunter3](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ahunter3/32/368_2.png) [@AHunter3](https://boards.straightdope.com/u/AHunter3)\ **Post date:** [May 6, 2004, 6:27pm UTC](https://boards.straightdope.com/t/suicide-by-9-volt-battery/243473/31 "2004-05-06T18:27:05Z")
As a 12 year old, I once went to tighten up the loose coverplate on a 110 v 3-prong grounded outlet that our washing machine was normally plugged into, which was so loose it was rotated 90° . Thought I’d turned off the circuit at the circuit breaker but of course misread the label and pulled the wrong breaker. Hopped up on the washing machine for better angle, squatting, took screwdriver in hand to tighten the screw, and missed and got the blade right into the hot slot. Turned around mad as hell at whoever had just kicked me really really hard in the tailbone, I mean I’m not a violent person but I was truly furious, that _hurt_! I’ve zapped myself with household 110 on several other occasions, too, and have (obviously) survived to tell the tale. I’ve got my doubts about 9 volts being lethal except perhaps under extraordinary circumstances. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [May 6, 2004, 7:34pm UTC](https://boards.straightdope.com/t/suicide-by-9-volt-battery/243473/32 "2004-05-06T19:34:21Z")
> [@](#): > > Sure you can. Saying “nine volts is enough, if the current is high enough” is exactly equivalent to saying “nine volts if enough, if the resistance is low enough”. Given any two terms of the Ohm’s Law equation, and any 7th grader can calculate the third. Right, but we’ve got a specified resistor here, namely, the human body (or whichever portion of the human body we’re interested in, here). If, for instance, you’re trying to frizzle the heart, then you can look at current through the heart, or since all hearts have about the same resistance, you can equivalently look at voltage across the heart. And if we’re comparing electrodes on the surface of the skin to electrodes in open wounds, then you can say that the latter is more dangerous because the former because the current is higher, or you can say it’s more dangerous because less of the voltage is dropped across the skin, and more through the innards. Either description is exactly as correct as the other. ---
**Author:** ![Cartooniverse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cartooniverse/32/3084_2.png) [@Cartooniverse](https://boards.straightdope.com/u/Cartooniverse)\ **Post date:** [May 6, 2004, 9:05pm UTC](https://boards.straightdope.com/t/suicide-by-9-volt-battery/243473/33 "2004-05-06T21:05:57Z")
> [@Q.E.D.](#): > > Disclaimer: Please don’t eat 9 V batteries, or insert them into any body orifice. Heh. **Q.E.D.** said “orifice”. Heh. He meant it, too. 😃 As for the O.P., yeah NiCad’s get fiery-hot when shorting out. I have had the severe displeasure of having this happen more than once. 14.4 volts, 5 aH packs. Good thing my gear was protected by a breaker. Cartooniverse ---
**Author:** ![aerodave](https://avatars.discourse-cdn.com/v4/letter/a/f08c70/32.png) [@aerodave](https://boards.straightdope.com/u/aerodave)\ **Post date:** [May 7, 2004, 12:14am UTC](https://boards.straightdope.com/t/suicide-by-9-volt-battery/243473/34 "2004-05-07T00:14:18Z")
**Chronos** , don’t forget the internal resistance of the battery, which is not a given. 12V from a car battery (think one jumper cable in the mouth, the other “you know where”) is going to be different from two lantern batteries in series. The particular internal resistance determines how much amperage the battery is capable of putting out. Regular dry cells can only push so much current, and I think you’ll agree that they won’t be able to match the 500+ amps of a car battery. So there is somehting to be said for the whole “It’s not the volts, it’s the amps” adage. You can have different effects depending on the nature of the voltage source. ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [May 7, 2004, 2:23am UTC](https://boards.straightdope.com/t/suicide-by-9-volt-battery/243473/35 "2004-05-07T02:23:41Z")
> [@audilover](#): > > **Chronos** , don’t forget the internal resistance of the battery, which is not a given. > > 12V from a car battery (think one jumper cable in the mouth, the other “you know where”) is going to be different from two lantern batteries in series. The particular internal resistance determines how much amperage the battery is capable of putting out. Regular dry cells can only push so much current, and I think you’ll agree that they won’t be able to match the 500+ amps of a car battery. > > So there is somehting to be said for the whole “It’s not the volts, it’s the amps” adage. You can have different effects depending on the nature of the voltage source. Sorry **audilover** , but this is wrong. When it comes to electrocution, current capability (a.k.a. compliance current) doesn’t matter a whole lot. This is because the current is determined by the voltage and body resistance. As long as the battery is able to source over 20 mA into your body while (more-or-less) maintaining its voltage, then the maximum current capability of the battery doesn’t matter. In this respect, a 12 V battery with 2 ohms of source resistance is just as lethal as a 12 V battery with 0.01 ohms of source resistance. As long as the battery’s internal resistance is much smaller than the body resistance, you can safely neglect it from the equations. Here’s an example. Let’s say a car battery is modeled as 12 V in series with 0.01 ohms. Let’s also say two 6 V lantern batteries (in series) is modeled as 12 V in series with 2 ohms. (These are typical values, BTW.) Note that the latter has 200X as much source resistance as the former. Let’s say your body resistance (assuming the skin is broken) is 500 ohms. If you get zapped with the car battery, you will receive 24.00 mA at 11.9998 V. If you get zapped with the lantern batteries, you will receive 23.9 mA at 11.9522 V. Not much difference, really. Heck, let’s take a 9V alkaline battery. Let’s assume it has a source resistance of about 10 ohms. If you get zapped with the 9V battery, you will receive 17.65 mA at 8.824 V. Hell, that’s almost as much current as what you’d receive from the car battery… [Previous page](https://boards.straightdope.com/t/suicide-by-9-volt-battery/243473.md?page=1)