AmazonBasics, Amazon’s store brand, launched over 10 years ago, and we know as little about it now as we do about Amazon as a whole. Like most details about Amazon, the origins of AmazonBasics products are a mystery.

In an article for OneZero, Sarah Emerson uncovered the origins of one of Amazon’s best-selling products: the AmazonBasics AA battery. She traces the battery straight to the source and works her way to the end of the product’s life cycle, pointing out where the trail gets murky. She does a great job of explaining the environmental impact and ethical concerns involved in alkaline battery production along the way. While Amazon won’t reveal details about its suppliers on its own, it did confirm Emerson’s reporting.

Here are a few surprising things I learned reading this article:

One out of every $10 of AmazonBasics sales goes to batteries, and the AA battery makes up about 4 percent of AmazonBasics’ sales, which is apparently enough for AmazonBasics to overtake established battery brands like Energizer and Panasonic.

Batteries are produced largely and ironically using fossil fuels, and they are only able to supply less than 1 percent of the amount of energy used to produce them. When you add up all of the emissions, a battery-powered device actually has a larger carbon footprint than an appliance that’s plugged into a wall.

There’s still a lack of consensus when it comes to what you should do with your battery at the end of its life cycle. There’s no policy that says whether batteries are toxic or if it’s okay to throw them in the trash. Collecting and recycling batteries requires so much energy that in the end, it wouldn’t actually save any energy.

For the full story of the AmazonBasics battery, read the whole piece on OneZero.