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    Battery fires

    Anyone know what conditions a battery is likely to catch fire?

    My Guesses:

    Overcharging with a dumb charger
    Charging a an overly fast rate >4ah
    Penetrating a battery with a knife (see U-tube)
    Extremely fast discharge (dead short)

    Can battery's catch fire just sitting there


    #2
    Batteries just sitting are significantly less likely to fault to flame. When it does happen it is likely due to internal shorts or other physical defects combined with temperature cycling and / or effects from vibration or changes in atmospheric pressure. Something triggers it. A pinhole might set up a slow reaction with moisture from the air, also.
    Alan B

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      #3
      You left out running it down past its minimum voltage. Creates metallic deposits in the electrolyte, I believe, as does overcharging, These are what can cause shorts circuits, self heat heating, and fires while just sitting there.

      The BMS and the bike controller both have circuits that prevent running down too low. The charger and the BMS also have safe guards against over charge. Still, it's probably safer to run chargers on a timer in case we forget and leave it run two days or more.

      What caused all those hover board fires? Probably cheap cells that just shorted out chemically.





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        #4
        Basically, shorts are the common cause of fires. As mentioned, above, there are many potential causes of shorts.

        BMS should protect the pack against external shorts. Power wires rubbing together, stuff like that.

        Internal shorts within cells are beyond control of BMS, so can drain the energy too fast, once initiated. That makes the heat. Potentially fire. Then the heat can spread to adjacent cells and cause a cascade effect. Some of the scenarios can take a while to play out, thus appear to 'just happen while the pack is sitting there', but if that does occur, it's likely there was a prior cause of some sort. Improper voltage, current, physical damage, manufacturing defect, etc...

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