Dell D520 beeping

Hi everyone, 

I own an old dell D520 that now runs Cloudready, but it produces a very annoying beeping sound when connected to the charger(not coming from the speakers, but from the laptop itself)? When it's unplugged it's fine. I tried looking in the BIOS itself but can't find anything to disable it... I read on an old article involving Bluetooth and disabling a setting but since it doesn't"t run Windows anymore i can't use that. 

Any help would be appreciated!

Thank you