Button cell

So this patient was four.

She was a four-year-old little girl, and she had swallowed a button battery, one of those very small, flat silver batteries that you get in toys and remote controls and car keys as well.

They are a really dangerous thing, and sometimes birthday cards as well, the ones that make sound.

And here's the thing that so many people don't realize about these button batteries.

A digital LCD also consumes very little power to maintain its display.

Casio designs certain models around long-life batteries, such as the CR2025 lithium cell.

Watches like the AE1200 and W800H are officially specified for approximately 10 years of battery life under the company's standard assumptions.

That last phrase matters.