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What is the worst case scenario if thermal runaway occurs?

  • A
    Fire.
  • B
    Engine failure.
  • C
    Total loss of electrical power.
  • D
    Overcurrent in the electrical system.
Learning Objective 021.09.02.01.10: Describe how to contain a battery thermal runaway highlighting the following: how one cell can affect the neighbouring cells; challenges if it happens in an aircraft during flight.

One of the biggest threats to Ni-Cd (Nickel Cadmium) and Lithium Ion Batteries is the risk of thermal runaway. The basic idea of thermal runaway is that if the battery becomes too hot (usually during charging), its internal resistance will change, causing it to produce more heat, hence heating it up further, causing a positive feedback loop that ends in extreme overheating. Lithium Ion batteries are more prone to it than the old Ni-Cd batteries, and it can happen much more quickly. It often happens due to overcharging/overheating and a combination of the two.

The worst case scenario is that a fire begins. Fire is pretty much the worst case scenario onboard any aircraft, other than complete structural failure perhaps, and lithium ion battery fires burn extremely hot. Ni-Cd fires are not as hot, but any fire is extremely bad, and these batteries are usually stored away from where people can contain the fires.

Electrical failure could happen also, as the battery will become unusable as part of this process, and it could do significant damage to the electrical system eventually, but that is still not nearly as bad as any sort of fire.

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