I recently did a World Peace run. Despite my joycons being fully charged, they only lasted about 40 minutes before the left one ran out of battery. Four more times across the run it ran out of battery, and I had to essentially play in short bursts before putting it on for a minute. I ended up PBing by exactly one second, and this run is now one of my favorite ones ever.

It's specifically the left Joycon, the right is all right and lasted me the whole run. But is there any way to ensure this doesn't happen? My left Joycon has nearly no battery life.

Is it quite an old pair? Batteries degrade over time, especially quickly if they're often kept fully charged like joycons. Not sure why the right one wouldn't have the same issue though, especially since it likely consumes more power

I've had the same Joycons since I got my Switch. I'll try another run today to see if the issue persists.

Weird. Maybe they're faulty. Although there's not much you can do if they're out of warranty. I guess maybe you could wait for them to drift and then hope that the repair replaces them?