Solved! Laptop constantly switches from AC to Battery

[gabrieltaets]

I own an Asus X550LNV for 2 and a half years now. A couple of months ago I formatted it and did a clean install of Windows 10. Since then, it randomly starts to switch from AC to Battery, even though it is always connected. After a couple minutes it stops, only to return the odd behaviour again some time later. I have noticed that the issue is more frequent when the computer is under intense use/heat (when the nvidia gpu is on, for instance), although not limited to these circumstances.
I have also noticed that when the laptop is shut down, if I leave it connected to the power outlet, it makes a very high frequency noise with a low volume. If I unplug it however, the noise stops.

The weird thing is that before I formatted it, the issue didn't exist.
Could faulty drivers cause this behaviour? Or am I looking to a defective motherboard?

Here is a video showing the odd behaviour:
[video="https/www.youtube.com/watch?v=Df0upjeiey0"][/video]

 

[dudeman509]

Looks like the charger's going bad - or the charging circuitry on the board.

I had an Acer do this when I had a lower-wattage charger connected to it than it needed.

 

[gabrieltaets]

Looks like the charger's going bad - or the charging circuitry on the board.

I had an Acer do this when I had a lower-wattage charger connected to it than it needed.

The charging circuitry on the board is a possible candidate -- the high pitched noise I hear when the laptop is shut down and plugged in comes from the board (although I have not disassembled the laptop yet in order to precisely locate where it comes from).
I don't think the charger's at fault here, because it worked just fine before formatting, but I can be mistaken.
I have now just removed the battery to see what happens. So far, the laptop is working fine and the issue has not appeared yet. I will put it under some stress to see if the issues comes back or if it will shut down completely. But so far it seems to me like a battery problem (as weird as it sounds).

-- EDIT --
Okay, so after putting the laptop under some stress, it shut down. So, not the battery's fault. Maybe the charger is unable to provide the needed wattage?

 

[dudeman509]

-- EDIT --
Okay, so after putting the laptop under some stress, it shut down. So, not the battery's fault. Maybe the charger is unable to provide the needed wattage?

That would be my guess. Most of them are pretty cheap circuitry. I've had multiple Dell chargers flake out over the years.