Lithium ion battery inflation

Discussion in 'The Projects Forum' started by nakulnasa, Nov 10, 2010.

  1. nakulnasa

    Thread Starter New Member

    Oct 15, 2010
    8
    1
    Hi

    I have two Lithium Ion Batteries of 12v and capability of providing 6500 ampere for 1 hour. I connected these two batteries in series to add up the voltage to 24 volts, The circuit was kept open for more than three days. Then i noted that the batteries are inflated in their sizes. And their voltage level also was reduced to 5 volts individually. I can't sort out the reason for this inflation.

    Can any body help me giving the reason for the inflation.
     
  2. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,699
    905
    Are you certain they are lithium ion batteries and not lithium polymer (LiPo)?

    What shape are they?

    What were they doing for the three days? Was there any source of discharge?

    How did you connect them in series? That is, was it a mechanical connection or did you solder them? Do you have a picture?

    Finally, they are most likely 6.5 AH, not 6500 AH batteries.

    Over discharged lithium batteries, as these are, may be a fire hazard. Be sure they are stored where they will not damage other property if they catch fire.

    John
     
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  3. Artikbot

    Member

    Nov 7, 2010
    45
    1
    Both LiIon and LiPo inflate and eventually explode.

    If the batteries hare each 5V, then you have why did they inflate. Excessive discharges over lithium chemistry (apart from LiFe, those seem to be indestructible) cause the cells to inflate, and if the discharge is done fast enough, they tend to leak chemicals all over the place.

    An inflated cell is totally unrecovable.

    Don't you have a protection circuit on the battery?
     
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  4. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    The warning labels on my Lithium batteries say to move them away from everything if they swell. Because then they might blow up or catch on fire!
     
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  5. nakulnasa

    Thread Starter New Member

    Oct 15, 2010
    8
    1
    Thank You
    Yes it was connected to a H-Bridge relay circuit. The relay coil rating is 5v controlled by controller using the Uln2003 to drive the relay. I checked mechanically there was no shot in the circuit. But only when the Uln2003 is connected to the circuit the difference between the vcc and the ground shows 600 ohms. Will this be the cause.


    And yes it is 6500 milliampere hour
     
    Mad Mike likes this.
  6. Artikbot

    Member

    Nov 7, 2010
    45
    1
    That resistance can be the bleeder resistor of the circuitry to make your cells discharge until they achieve the same charge levels...
     
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