How To Calculate Internal Heat Generation In Batteries


 
Internal heat generation during the operation of a cell or battery is a critical concern for the battery engineer.

If cells or batteries get too hot, they can rupture or explode.  And Lithium and Lithium-ion cells/batteries can catch on fire when they rupture, creating even more of a safety hazard.

To ensure safe operation over the entire intended operating range of a cell or battery, it is crucial that the battery engineer understands the fundamentals of internal heat generation and be able to calculate the expected adiabatic temperature rise of a cell or battery under any operating condition.  The objective of this article is to provide that fundamental understanding and the methodology for making those calculations.

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The Arrhenius Theory of Accelerated Testing

Microprocessor-1

 

Accelerated testing is crucial in the development and quality control of many devices including batteries, integrated circuits, microprocessors, etc.  Anything that has a multi-year shelf-life or life cycle.

Alkaline batteries, for example, are often advertized to have a 10-year shelf-life.  The only way to test such an extreme shelf-life and to verify this claim is through accelerated test methods.  To be sure, real time testing is also done as a final verification, but by the time those results are in, the batteries have long since left the manufacturing plant and are in the hands of customers.  The last thing any manufacturer wants is for customers to find the flaws in their products.  Thus, manufacturers must have test methods that root out flaws and defects long before customers ever see them.

The most often used accelerator in accelerated testing methods is temperature.  By increasing the temperature, degradation reactions are sped up and failure is accelerated.  By testing to failure at multiple temperatures, the time-to-failure can be extrapolated back to room temperature where real-time testing is impractical for quality control or product development activities.

Here is the scientific foundation for elevated temperature accelerated testing.

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Finally Revealed: The Secret Agent for Seasoning Cast Iron BBQ Grates So They Don’t Rust

Ribs C3

 

Science has a lot of neat applications around the house and in our everyday lives.

Here’s one of them.

I have a BBQ with cast iron grates and I have a love-hate relationship with the thing.

I love how the cast iron grates cook my food.  Their high thermal mass provides uniform heating and helps get my steaks done just right every time.  They just seem to cook food much better than stainless steel or other materials.

But I hate the cast iron grates because they rust.  No matter how careful you are with them, even if they are porcelain coated, which mine are, they will eventually rust.  And once they start, they can really, really rust.

Definitely not a good situation.

So, what is the solution?

Let’s take a look at what works and what doesn’t.

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