Same problem here, so I've made some searches.
The answers given here are totally correct, but not complete.
The consequences of this problem:
The system is dramatically slowed down, (of course, even if you remove the warning message in the BIOS settings).
If the problem comes from your charger, the risk is that you will be unable to power on your computer sooner or later.
The reason why the system is slowed down is given in their error message:
The performance will adapt to your system...
meaning: As they don't know which kind of charger you use, to be safe, they will downngrade the processor speed (underclocked), to prevent things maybe like fire, exploding battery, apocalypse, I don't know.
First, a common misconception:
- It had no link with the battery itself. If a battery is not "recognized", it shows another kind of message saying something like "no battery", or in the same style.
So, replacing the battery do nothing, it's a different problem.
And it can have at least 4 or 5 totally different causes:
- The central pin of the plug (S.M.A.R.T system), not aligned with the hole on the laptop socket. As mentioned in the answers here, this central pin is here to make the charger "recognized" by the BIOS. It's to prevent power supply that is not adapted, too weak or too strong, and can cause damages to the battery (or worse).
And if it's not aligned, it can be because it twisted, so to solve it, some people had good results with a tweezer. Some by twisting the wire. Or buying a new (genuine) charger.
Be warned that sometimes it solve the problem for a limited time, and after a while, the message and the system slow down come back.
It can also be a dirt in this place, try to clean or to blow on it.
https://www.dell.com/community/XPS/XPS-13-9360-Plugged-in-not-charging-Adapter-not-recognized/td-p/6244459
The charger is not genuine. As with S.M.A.R.T technology, the charger (and probably battery) have to be genuine (OEM). If the charger is not genuine, the pin is not made with the same technology than the genuine one. It's automatically detected.
It can also be on the computer side, the socket connector of the computer being damaged, in such a way that buying a new charger doesn't solve the problem.
You can test wether it's on the computer side or on the charger side by using another (genuine) charger with the computer, to see if it solves the problem (some electronics & computing shops can let you try their for free probably), or try your charger on a different (DELL) computer.
In this case, you have to buy a new (genuine) power socket remplacement for your computer (source)
It can also be an electronic component of the motherboard that is burnt. In this case, replacing the socket or the charger won't do anything, of course.
It can be an error of communication between the motherboard and the charger, some people managed to fix this error by resetting the battery (sensor)
Steps here: https://www.ncconsumer.org/news-articles-eg/resetting-a-dell-laptop-battery-in-five-quick-steps.html
1. Completely power down the laptop and remove the cord from the
computer.
2. Flip the laptop over.
3. Push on the battery release button or buttons to release the battery
form the computer and remove the battery.
4. Power on the computer without the battery, allowing it to boot
completely.
5. Completely power the computer down and remove the cord once again.
6. Reinstall the battery, plug in the power adapter and re-boot the
computer.
This solve the communication between the charger and the BIOS.
- Some people reported this problem after a BIOS update. If it's true, it goes in the category "bad communication between charger and BIOS/motherboard". It doesn't seem the most common, the plug problems seem really more common, but you can always try to downgrade or upgrade the BIOS (wisely, without bricking your system).