LiPo battery explosion.

Discussion in 'General Electronics Chat' started by droggie, Jan 5, 2013.

  1. droggie

    Thread Starter Member

    Oct 21, 2012
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    A couple of days ago I took a spare RC helicopter apart and took its four motors and 3.7v rechargeable LiPo battery connected to a pcb. I had been using it to power some LEDs on my bread board and it worked fine. Today I added a toggle switch within the same power buses on my bread board because I wanted to see if I could power the motors on and off. the motors would not work and the battery suddenly combusted. What could have happened? I'm guessing when I soldered wires to the same solder points as the battery something went wrong...
     
  2. tubeguy

    Well-Known Member

    Nov 3, 2012
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    Just guessing.. probably accidentally wired in the switch as a dead short...:(
    Post pictures for a definite answer.
     
  3. droggie

    Thread Starter Member

    Oct 21, 2012
    137
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    I threw the battery almost immediately..
     
  4. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    I agree with tubeguy. You probably wired it in so that it shorts the battery. LiPos are really sensitive to back EMF and shorts. I had one explode in my hands once. Smelled like candy, but I chucked it out the window right away :D
     
  5. droggie

    Thread Starter Member

    Oct 21, 2012
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    What do you mean by short in this context. I could I have wired it alternatively?
     
  6. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    The word "short" means a direct connection between a terminal with a relative high potential and one with a relative low potential. In this case, I'm guessing you connected the switch directly between positive and negative. It should be connected in series with the positive line (connecting + of the battery to the + bus).

    A photo of your setup would be most helpful.
     
  7. droggie

    Thread Starter Member

    Oct 21, 2012
    137
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    Here is a diagram I tried to draw...
     
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  8. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    That diagram is very difficult to follow, because you have a lot of wires crossing over, and lines that aren't wires, etc. Could you please try to draw it a little neater, with as few overlapping or crossing lines as possible?

    If I'm seeing it right, it looks like you connected the switch directly across the battery, which will SHORT it.
     
  9. droggie

    Thread Starter Member

    Oct 21, 2012
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    I connected the battery and switch within the same bus. Then from that bus I attached two wires to a motor, then it exploded.
     
  10. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    That doesn't make any sense, what you're telling me. Saying you "connected the battery and switch within the same bus" doesn't make it any easier to understand. What do you mean you connected them "within the same bus"?

    Like I said, a neater, clearer diagram would be much more helpful than trying to describe what you did.
     
  11. droggie

    Thread Starter Member

    Oct 21, 2012
    137
    1
    Here is another attempt at a diagram.
     
  12. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    Yup, you're shorting the battery with the switch. NEVER connect a switch directly between buses or between the terminals of a battery. EVER! The way you have it now, when the switch is closed you're directly connecting the + bus to the - bus. This is a SHORT. That is why nothing worked and your battery exploded.

    Instead, you need to connect one pin of your switch to the + terminal of the battery, and the other pin of the switch to the + bus. Don't connect the + terminal of the battery directly to the bus.

    Here's a quick MSPaint rendering:
    [​IMG]

    That is just of the connection for the battery, switch, and LED. I'm ignoring the other PCB for now.

    By the way, do you know how to draw schematic diagrams? If you don't, I highly recommend you learn immediately. Otherwise you won't get very far.

    Regards,
    Matt
     
  13. droggie

    Thread Starter Member

    Oct 21, 2012
    137
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    What about the ground connections? I do know how to draw schematics, just not very well with paint.
     
  14. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    What ABOUT ground connections? The negative side of your battery is the ground. It's all there.
     
  15. droggie

    Thread Starter Member

    Oct 21, 2012
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    My mistake, gotcha! So don't connect the switch directly with the battery?
     
  16. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    Don't connect the switch ACROSS the battery. Meaning, do not connect one pin of the switch to + and the other pin to -. This will connect the two together, which is a short. Connect it the way you see it in my diagram and you should be fine :)

    Good luck!
     
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