battery-notification
Every other low battery icon, notification, etc. in the world doesn't work for my brain. This one gives a small out of the way notification once a minute so I can't just say "oh one more minute", immediately forget and then let my battery drain until I'm greeted with a black screen. So if you need a battery notification that will annoy you less than the windows in-your-face popup while still actually getting the job done, this might work for you, no clue.
Install
cargo install --git https://github.com/jam1garner/battery-notification
Then setup, in your platform specific way, a means of having this launch in the background on boot.