I have a phone that has no sim card and I only use it for podcasts (using wifi). I found it strange that different places I took it changed how long the battery lasted. I was going on the idea that it was about the wifi. But as I traveled to different places, and different countries, I saw a radical change in the battery life. I could go over a week in small country and then in the US it would drain in two days.

I finally turned the airplane mode on and it returned to the level of outside US small country in terms of battery life.

What the hell is that device doing when in the US? Its terrifying actually.