### Author:  [@Irishman](https://boards.straightdope.com/u/Irishman)
#### Post date: [April 2, 2014, 9:29am UTC](https://boards.straightdope.com/t/what-happens-if-you-hook-2-9-volt-batteries-together/292321/41 "2014-04-02T09:29:38Z")
> [@tempaccountforasinglepost](#):
>
> Hi im a college student and we just did this as an experiment. After several minutes there was a pop and a puff of smoke as one side blew out. A few minutes after (long enough to find this thread on google and start reading people saying an explosion would not happen) the other side popped with smoke as well.
Thanks for the update. It’s good to know we guessed right. 😉
> [@njaohnt](#):
>
> Thanks, putting a strip of paper is a good idea.
> Why wouldn’t it create a current? What is the difference if a the current flows to a negative terminal on the same, or a different battery?
You seem to have a poor understanding of how a battery works, and electrical circuits in general. That’s okay, we all have to learn.
The key word you are not catching is the word _circuit_ - i.e. a circle. You have to close the loop. We label terminals positive and negative, but there’s no magic that makes all negatives the _same_ negative. All those labels mean is that there is a voltage, and there is a high side and a low side to the voltage.
When you connect the high side of one battery to the low side of another battery, you have not closed the loop, i.e. completed the circuit. You have stacked one battery on top of another battery.
Two batteries side by side. Terminals not connected.
```auto
(+) (+)
9V 9V
(-) (-)
```
You see, no lines between means no connections, so no circuit, no current flow.
Two batteries connected in a circuit
```auto
(+) _____ (-)
9V 9V
(-) _____ (+)
```
See the lines between terminals? See how it makes the batteries into a loop? A big O or box?
Two batteries connected as you suggest, one positive to the other negative only
```auto
(+)
9V
(-) _____ (+)
9V
(-)
```
See how there is nothing closing the loop?
---
### Author:  [@Mangetout](https://boards.straightdope.com/u/Mangetout)
#### Post date: [April 2, 2014, 11:24am UTC](https://boards.straightdope.com/t/what-happens-if-you-hook-2-9-volt-batteries-together/292321/42 "2014-04-02T11:24:34Z")
\
---
### Author:  [@AaronX](https://boards.straightdope.com/u/AaronX)
#### Post date: [April 2, 2014, 11:35am UTC](https://boards.straightdope.com/t/what-happens-if-you-hook-2-9-volt-batteries-together/292321/43 "2014-04-02T11:35:11Z")
> [@tempaccountforasinglepost](#):
>
> Hi im a college student and we just did this as an experiment. After several minutes there was a pop and a puff of smoke as one side blew out. A few minutes after (long enough to find this thread on google and start reading people saying an explosion would not happen) the other side popped with smoke as well.
Doing experiments to test things out, an honest username, we need more posters like you.
---
### Author:  [@Mangetout](https://boards.straightdope.com/u/Mangetout)
#### Post date: [April 2, 2014, 12:21pm UTC](https://boards.straightdope.com/t/what-happens-if-you-hook-2-9-volt-batteries-together/292321/44 "2014-04-02T12:21:48Z")
> [@AaronX](#):
>
> Doing experiments to test things out, an honest username, we need more posters like you.
Agreed. I’ll start sharpening the guillotine…
---
### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [April 2, 2014, 3:12pm UTC](https://boards.straightdope.com/t/what-happens-if-you-hook-2-9-volt-batteries-together/292321/45 "2014-04-02T15:12:38Z")
I’m surprised that both batteries popped open. I would have thought that the first one popping would break the circuit.
---
### Author:  [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)
#### Post date: [April 2, 2014, 3:25pm UTC](https://boards.straightdope.com/t/what-happens-if-you-hook-2-9-volt-batteries-together/292321/46 "2014-04-02T15:25:53Z")
[Video.](https://www.youtube.com/watch?v=iZ12XGAwoc8) Either watch the whole thing, or skip to about the 8-minute mark,
---
### Author:  [@BubbaDog](https://boards.straightdope.com/u/BubbaDog)
#### Post date: [April 2, 2014, 3:41pm UTC](https://boards.straightdope.com/t/what-happens-if-you-hook-2-9-volt-batteries-together/292321/47 "2014-04-02T15:41:00Z")
**Irishman** ,
While your post was informative I think that **njaohnt** may not read it. He joined in April 2012, made 3 posts, and has not posted since.
This goes beyond a zombie thread as its reanimation includes batteries and electricity. I’d say its a Frankenstein thread.
---
### Author:  [@gnoitall](https://boards.straightdope.com/u/gnoitall)
#### Post date: [April 2, 2014, 3:42pm UTC](https://boards.straightdope.com/t/what-happens-if-you-hook-2-9-volt-batteries-together/292321/48 "2014-04-02T15:42:13Z")
> [@Chronos](#):
>
> I’m surprised that both batteries popped open. I would have thought that the first one popping would break the circuit.
I could imagine the first battery failing in a fashion that shorted the cell elements together, continuing the circuit even after case rupture. And as long as there’s some electrolyte, there’d still be some continuity through it.
The other battery was probably also close to rupture at that point, and wouldn’t have needed much more to finish.
---
### Author:  [@Skammer](https://boards.straightdope.com/u/Skammer)
#### Post date: [April 2, 2014, 4:35pm UTC](https://boards.straightdope.com/t/what-happens-if-you-hook-2-9-volt-batteries-together/292321/49 "2014-04-02T16:35:20Z")
Someone pointed me to a video a few months ago (probably on YouTube) where someone was describing how their house burned down because of a 9v battery tossed into a drawer with a piece of metal that caused a short circuit. I can’t access YT right now to get the link. Since seeing that I do not store loose 9v batteries with the terminals exposed.
---
### Author:  [@FoieGrasIsEvil](https://boards.straightdope.com/u/FoieGrasIsEvil)
#### Post date: [April 2, 2014, 7:07pm UTC](https://boards.straightdope.com/t/what-happens-if-you-hook-2-9-volt-batteries-together/292321/50 "2014-04-02T19:07:57Z")
What’s the record for how many times a zombie thread has been resurrected without being closed? Here we’ve got 2005-2011-2012-2014. Not too shabby!
---
### Author:  [@TriPolar](https://boards.straightdope.com/u/TriPolar)
#### Post date: [April 2, 2014, 7:12pm UTC](https://boards.straightdope.com/t/what-happens-if-you-hook-2-9-volt-batteries-together/292321/51 "2014-04-02T19:12:49Z")
My friends and I experimented with this as children. I can tell you that connecting two carbon 9V batteries together will result in a lot of heat, but not enough to set off a single cap-gun cap in the whole roll we wrapped around them. No exploding battery either. They were useless afterwards.
---
### Author:  [@MindsEye\_Watering](https://boards.straightdope.com/u/MindsEye_Watering)
#### Post date: [April 2, 2014, 7:23pm UTC](https://boards.straightdope.com/t/what-happens-if-you-hook-2-9-volt-batteries-together/292321/52 "2014-04-02T19:23:18Z")
> [@Skammer](#):
>
> Someone pointed me to a video a few months ago (probably on YouTube) where someone was describing how their house burned down because of a 9v battery tossed into a drawer with a piece of metal that caused a short circuit. I can’t access YT right now to get the link. Since seeing that I do not store loose 9v batteries with the terminals exposed.
> **[Something We All Have In Our Homes Started This House Fire](https://themotherlist.com/something-homes-started-house-fire/)**
>
> You won’t believe what caused the fire in this man’s home. His one lesson about the cause of the fire is so incredibly important. Pass it on!
---
### Author:  [@Mangetout](https://boards.straightdope.com/u/Mangetout)
#### Post date: [April 2, 2014, 8:19pm UTC](https://boards.straightdope.com/t/what-happens-if-you-hook-2-9-volt-batteries-together/292321/53 "2014-04-02T20:19:47Z")
> [@Chronos](#):
>
> I’m surprised that both batteries popped open. I would have thought that the first one popping would break the circuit.
I imagine it was just gases venting from one of the cells inside - quite catastrophic bursting would be necessary to break the circuit - it would have to tear apart the anode and cathode so as to separate them from one another completely.
(The inside of a PP3 9v battery comprises six cylindrical cells in series - which have the same internal [structure](http://en.wikipedia.org/wiki/File:Alkaline-battery-english.svg)as ordinary AA cells etc - just smaller)
---
### Author:  [@Kelevra](https://boards.straightdope.com/u/Kelevra)
#### Post date: [April 4, 2014, 6:56pm UTC](https://boards.straightdope.com/t/what-happens-if-you-hook-2-9-volt-batteries-together/292321/54 "2014-04-04T18:56:34Z")
Here’s a youtube clip of welding using 85 9V batteries.
I’m curious how hot they would get and how long the current would last. Not curious enough to buy 85 batteries though!
---
### Author:  [@Irishman](https://boards.straightdope.com/u/Irishman)
#### Post date: [April 6, 2014, 1:58am UTC](https://boards.straightdope.com/t/what-happens-if-you-hook-2-9-volt-batteries-together/292321/55 "2014-04-06T01:58:45Z")
> [@BubbaDog](#):
>
> **Irishman** ,
> While your post was informative I think that **njaohnt** may not read it. He joined in April 2012, made 3 posts, and has not posted since.
I spotted that, but it was too good a point not to make.
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