Total Energy released in battery fire

[Paddy]

hi all

I’m wondering what the total energy that gets released in a battery fire. Assuming it is a lithium ion battery as used in Tesla EVs. Assuming that the battery is fully charged.

As a non battery expert, and a non chemist, I am making a guess that the lithium will oxidise, releasing the same quantity of energy’s that battery is rated for. After that, I’m assuming that there will be further chemical reactions that take place, but I have no idea on what they would be, or whether they are a first order effect, or a second order effect in terms of magnitude of energy released.

So TER = BR + OCE

Where TER = the total energy released
BR = battery rating
OCE = Other chemical energy

Is OCE significant, or even perhaps larger than BR?

Thanks

Dan

 

[Paddy]

Bump

The reason I am asking this is because, if you have a high performance ICE vehicle, with an 80 litre fuel tank, then that contains 80L * 3.42MJ/L = 2,700MJ of energy.

A high performance 100kWh EV will have 0.100 * 60 * 60 MJ = 360MJ of energy.

So if both explode, unless there is extra chemical energy released that I have not accounted for, then the ICE will explode with 7.5 X the energy of the EV. Hence the ICE vehicle is nearly an order of magnitude more dangerous.

What is wrong with my calculation?

 

[David99]

You are right, there is far less energy in a battery than in a typical petrol tank. There a few things to consider, though. The petrol tank on average is only half full. Same is true for the battery, though.

Battery files are usually slow and gradually build up. The battery pack is designed to slow down the spread of heat and fire if it happens. Gasoline is a liquid and leaks into the open where it can burn much better. A gasoline fire can grow big very quick.

I'm not an expert ether but I was told a burning Lithium cell releases it's own oxygen thus it doesn't need it from the air. This is why it is recommended to use lots of water to cool down the batteries which will stop the chemical reaction and thus the fire. To calculate how much energy is fueling the fire I believe you have to understand and calculate the chemical reactions happening. The electrical energy stored in a battery is not what fuels the fire, it's certain chemicals reactions. I'm not sure how to calculate them as I don't know what's exactly inside and in what quantity. Once the other materials in the car catch on fire, that's what keeps the fire fueling and both ICE and EVs are the same.

Because battery fires in EVs are slowly growing and far less violent I would say it's the safer of the two alternatives. The leaking gasoline also causes more danger to the surrounding areas.