Two commonly held untruths about laptop batteries:
1) They last forever.
No! With care, the original batteries can last from 3-5 years. Replacements rarely hold up longer than two years.
2) You should always leave them plugged in.
No! This habit is a battery killer. A battery needs to discharge and charge up. Leaving it plugged in could lead to overheating. Lithium batteries can also become bloated and in the worst case, explode and start a fire. That’s why they are not allowed in airplane cargo.
Dok recommends: charge your device overnight, and unplug it in the morning. Most computers will tell you when the battery is low. For a PC, it’s on the bottom right. Wait for the signal to show that it’s low, before plugging it in again.