Weird scratchy noise while charging

I went to charge my MacBook Air today and I noticed a weird sound coming from the computer when I plugged it in. It sounded just like the noise a hard drive makes (obviously the MBA has flash storage, not a HD). I don't know if maybe there's something wrong with the fan, or if it has something to do with the charging port, or even worse, the battery. I'll just copy/paste my battery info here:

Model Information:

Serial Number: D8**********JAR

Manufacturer: SMP

Device Name: bq20z451

Pack Lot Code: 0

PCB Lot Code: 0

Firmware Version: 511

Hardware Revision: 000a

Cell Revision: 1210

Charge Information:

Charge Remaining (mAh): 7191

Fully Charged: No

Charging: Yes

Full Charge Capacity (mAh): 7264

Health Information:

Cycle Count: 146

Condition: Normal

Battery Installed: Yes

Amperage (mA): 695

Voltage (mV): 8563

System Power Settings:

AC Power:

System Sleep Timer (Minutes): 1

Disk Sleep Timer (Minutes): 10

Display Sleep Timer (Minutes): 10

Wake on AC Change: No

Wake on Clamshell Open: Yes

Wake on LAN: Yes

AutoPowerOff Delay: 14400

AutoPowerOff Enabled: 1

Current Power Source: Yes

DarkWakeBackgroundTasks: 1

Display Sleep Uses Dim: Yes

PrioritizeNetworkReachabilityOverSleep: 0

Standby Delay: 10800

Standby Enabled: 1

Battery Power:

System Sleep Timer (Minutes): 1

Disk Sleep Timer (Minutes): 10

Display Sleep Timer (Minutes): 2

Wake on AC Change: No

Wake on Clamshell Open: Yes

AutoPowerOff Delay: 14400

AutoPowerOff Enabled: 1

DarkWakeBackgroundTasks: 0

Display Sleep Uses Dim: Yes

Reduce Brightness: Yes

Standby Delay: 10800

Standby Enabled: 1

Hardware Configuration:

UPS Installed: No

AC Charger Information:

Connected: Yes

ID: 0x07a1

Wattage (W): 45

Family: 0x0085

Serial Number: 0x*****20f

Charging: Yes

It seems like the noise is occuring whenever I click the trackpad or while I'm scrolling (and it sounds exactly like a hard drive for some weird reason) and it only seems to happen when the adapter is plugged in. I'm guessing it has to do with either the charging port or the battery because when I remove the charger my laptop goes silent like it normally should. Any ideas on what might be going wrong??

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