AirPods are a really convenient way to listen to music, podcasts, talk on the phone hands-free, and ignore people you don't feel like interacting with—you can't hear them, so it's not your fault.
The battery on AirPods should last up to five hours if you're playing music or around two hours if you're talking on the phone. The charging case should be good for around 24 hours or 11 hours of talk time.
But sometimes life gets in the way of keeping them charged. There's a way around it—at least for a short period of time. What's the trick, you must be dying to know? Use only one AirPod at a time to extend the battery life.
While using one of the AirPods, leave the other in the charging case. Once it has enough battery, swap them. Using one AirPod is obviously not as glorious as using both, but you're the one who didn't keep them charged, so this inconvenience is on you.