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Topic: Battery Blew Up! (Read 3505 times) previous topic - next topic

adele

Hi,

I was working with my breadboard and I started to smell something bad, which I thought was the heater coming on in the house. It does that some times.

Then 9V blew up on my circuit.

I was trying to run power to each of my breadboards, and I added a switch to turn the circuit on and off so that I wouldn't have to keep disconnecting the battery.

The switch was off, and the LED was off, so there shouldn't have been any power running through the circuit but the battery still blew up. It took 30 mins for the battery to cool down enough so I could dispose of it.

I am going to start over with some beginning books to get more knowledge before I play with any more circuits because it freaked me out.

I uploaded a few pictures of my circuit, which I still have. Can someone tell me what I did wrong? I would like to know so I don't make the mistake again. I would like to know how I screwed up.

MAS3

#1
Dec 09, 2014, 11:06 pm Last Edit: Dec 09, 2014, 11:17 pm by MAS3
Hi adele.

Your 2nd. picture shows the switch.
Switches like that often have 4 pins (for some structural strength), which are connected 2 x 2.
There might also be 3 actual connections and 4 pins where the 2 common pins are conneted, and the switch connects either A or B to that.
The picture shows you have all wires to the switch in one row of the breadboard (which would be your 2nd mistake here), so they are always connected.
That means the switch doesn't even do anything.

Far worse (the 1st. mistake) is that you have connected the red and the black line coming from the battery to the switch.
That will blow up a battery allright.

Switches like these are only to connected to one wire from a battery, and the red (for positive) one is preferred.

Solution:
Remove all black wires to the switch.
Move the switch 4 positions to the left, bridging the gap in that breadboard.
Use another color wire (orange ?) between the other side of the switch to the 2nd red power rail on top.
Move all other red wires that you want to switch to the 2nd. red power rail (else the switch doesn't do any switching).

Have a look at "blink without delay".
Did you connect the grounds ?
Je kunt hier ook in het Nederlands terecht: http://arduino.cc/forum/index.php/board,77.0.html

adele

Hi,

This switch has 6 pins. It did work when I pressed the button, the light came on. I will look at the data sheet again for the switch to make sure I know how to hook it up correctly. The "in" always went to the same pin, but depending on which pin I used for the "out" it would set the position of the switch. One way, the switch would be on when it was up, and the other it would be on when it was down (it is a latching switch). There was also another pin that would make the switch on regardless of the position (up or down).

So you think the switch is what made the battery short out?

Grumpy_Mike

If you wire a switch across a battery you will cause it to supply all the current it can. If that is a lot then yes it will blow up every time. I have difficulty believing that you do not know this. You need to do a lot more reading about circuits before doing any more practical work.

adele

#4
Dec 10, 2014, 01:09 am Last Edit: Dec 10, 2014, 01:14 am by adele
If you wire a switch across a battery you will cause it to supply all the current it can. If that is a lot then yes it will blow up every time. I have difficulty believing that you do not know this. You need to do a lot more reading about circuits before doing any more practical work.
I only know what the Arduino book has showed me so far. The Arduino Projects Book that came with the starter kit shows on page 26 a switch where one end is connected to power and the other end is connected to an LED and ground.

So I don't understand what the difference is between the book's example and what I did.

The book doesn't show that both ends of the switch are connected to power. It shows power going into one side of the switch and ground on the other. So I was just copying that.

I am going to start back over with the book from the beginning and work through all of the projects again. I also have another projects book that I bought so I can start to understand it better.

MAS3

I just saw such a switch a few moments ago, during my daily visit in an online shop.
Having another peek at the 2nd. picture, you seem to have the red wire to a top pin, and the black wires to a center pin, the lower pin is then left unconnected.

The problem stays that you connected the black and the red wire, i do not know if that was while the switch was pressed or released.
The LED would have been on while the switch was open, and went off when you closed (shorted) it.

Let's assume you have learned today  :smiley-roll-sweat:

I see you have just replied.
The book shows a switch with one end to the battery and the other to the LED, which then is connected to the battery's black wire (i hope there is a resistor somewhere in there too).
That is not what you did.
You connected both wires from the battery to the switch.
Have a look at "blink without delay".
Did you connect the grounds ?
Je kunt hier ook in het Nederlands terecht: http://arduino.cc/forum/index.php/board,77.0.html

adele

#6
Dec 10, 2014, 01:29 am Last Edit: Dec 10, 2014, 01:31 am by adele
So I think I understand what I did wrong. By connecting the "in" on the switch to red and "out" to black, I basically shorted the battery in the same way that I would have if I connected a wire directly between the + and - of the battery.

So my problem is that I didn't have any components between the + and - of the battery. The switch basically acts like a jumper wire, not really a component.

So I could have connected one end of the switch to the + of the battery and the other to the - but I needed to have some components like resistors, LEDs, etc... in the circuit, so something was using the energy.

If I'm understanding correctly.

Edit: I understand that I can't short the + and - of a battery together, but I didn't realize that's what I was doing with this circuit. Which is why I asked here for help.

Grumpy_Mike

#7
Dec 10, 2014, 04:31 am Last Edit: Dec 10, 2014, 03:22 pm by Grumpy_Mike
Yes that is correct.
The clue is in the name 'circuit' it is a path that the current follows from the + to the -, unless there is something to limit the current then you end up making a heater out of the battery.
The relationship between the voltage and the current is given by ohms law, it is voltage divided by resistance equals current. All components have resistance. Your switch, which is a component, has a very small resistance, almost zero. That allows a very large current to flow.

adele

I knew that you couldn't short a battery out, but sometimes when I start hooking up the wires, I lose track of what is going on. It's still hard for me to understand how everything works when it's connected, since I can't actually see the electricity moving.

This is still a good lesson learned that will help me understand how to (not) do things in the future. When I look at the mess of wires and components, I can forget that there is a specific path that the circuit is following.

I want to think of a circuit as a point-to-point connection, always between the positive and negative. Then I see circuits with several components connecting to ground and several connections to positive, and I can't understand how it's working. It seems like it's no longer a circuit.

In my head, I think that only one component should ever be connected to positive, and one to ground, so it forms an actual "circuit", but the schematics don't look like that.

Hopefully, when I go back through the books, it will start to make sense.

Thanks

Grumpy_Mike

Quote
Then I see circuits with several components connecting to ground and several connections to positive, and I can't understand how it's working. It seems like it's no longer a circuit.
It is in fact several circuits all connected at the same time. This is known as connections in parallel. When the components are all in a single line from + to - this is known as "in series". Any none trivial circuit will have many current paths in series and in parallel.

Learn to think "schematic" and then translate that schematic into the "mess of wires" while you make it. Do not be tempted to do this the other way round because that eventually will get you nowhere.

Here are some links to help you start to think schematic:-
Reading a schematic
http://blog.makezine.com/archive/2011/01/reading-circuit-diagrams.html
Colin's Lab video on reading a schematic
https://www.youtube.com/watch?v=9cps7Q_IrX0

ghlawrence2000

#10
Dec 10, 2014, 12:35 pm Last Edit: Dec 10, 2014, 12:50 pm by ghlawrence2000
The relationship between the voltage and the current is given by ohms law, it is voltage divided by resistance equals resistance.
Sorry Mike, 2 out of 3 aint bad as they say....  ;)

He meant voltage divided by resistance equals current.

Graham

Here is a little something that is easy to remember to help with Ohms law, the triangle, if you cover V, you are are left with IR, V=IR. If you cover I you are left with V/R  I=V/R. If you cover R, you are left with V/I  R=V/I. Where V=Volts, I= Amps, R= Ohms.
UTFT_SdRaw now included in library manager!! ;) High speed image drawing from SD card to UTFT displays for Mega & DUE.
UTFT_GHL - a VASTLY upgraded version of UTFT_CTE. Coming soon to a TFT near you! 8) Shipping April 1 2016!

TomGeorge

Hi, what sort of battery was it?
Tom.... :)
Everything runs on smoke, let the smoke out, it stops running....

Grumpy_Mike

Hi, what sort of battery was it?
Well we know for sure it wasn't one of these:-

adele

Sorry Mike, 2 out of 3 aint bad as they say....  ;)

He meant voltage divided by resistance equals current.
Yeah, I figured that was a typing mistake. I knew what he meant. The book explained that on the first few pages.

It is in fact several circuits all connected at the same time. This is known as connections in parallel. When the components are all in a single line from + to - this is known as "in series". Any none trivial circuit will have many current paths in series and in parallel.
Thanks!

That helps a lot. The book explains series and parallel, but they use a very basic example. There are so many connections going on in larger circuits that I had no idea this is what was happening. It was hard for me to pick out that they were running in parallel. It just looks like a huge mess to me.

These little details help a lot. It's kind of like when I first started learning to program. I understood some of the concepts, but when I saw a huge "mess of code" I couldn't make heads or tails of it. Now I can look at it and tell that they are classes, with functions, etc...

Hi, what sort of battery was it?
Tom.... :)
I attached an image of the battery I was using, both before, and after the explosion. Let's just say, it was a lesson learned.

TomGeorge

HI, waaa????
Sorry, but I hope you mean a duracell, 9V with stud terminals like the picture posted like Grumpy_Mike posted.
Was it rechargeable.

Or was it a group of cells in series or parallel.
You see the problem I have is that you should have at least some damage to the protoboard, the leads and the switch if you cooked a battery, that is a lot of energy.

Did you make up a pack of cells, if so can you post a picture of a circuit diagram, hand drawn will do.
Sorry for the questions, but I fix electronic stuff, you see "its my job".

Tom....... :)
Everything runs on smoke, let the smoke out, it stops running....

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