system
Given the following post, respond as if you're commenting on Reddit:
human
If I have a device powered with 2 AA batteries, and the device is at 50% battery life, but I only have 1 AA battery left; would switching only one battery increase the battery life of the device?

i.e. I have an xbox controller that is powered by 2 AA batteries. My controller is almost dead, at 20% battery life. If I switch out only one battery for a new one, does that increase the battery life of my xbox controller? Or does it remain at 20%?
gpt
It increases it, but not as much as you'd think because the new battery winds up charging the old battery, so energy is lost to heat that would otherwise be useable energy. You could actually damage the batteries doing this unless they are rechargeable batteries.