Q: MacBook Air (Mid-2012) Battery Not Charging/Charging Very Slowly

Hey guys, so this has been happening for a while and I feel like I can no longer utilize my MacBook for my school work, therefore I'm posting here to possibly get some help. I have a MacBook Air (Mid-2012), the model number is A1466. The battery would charge normally if I left it plugged in and I didn't use the MacBook overnight, then it would be charged to 100% in the morning. But when I am using the MacBook with my charger plugged in, even for simple tasks such as opening my email, the battery would still slowly decrease its way to 0%. When I plug the charger in, the battery status shows "Battery Not Charging" and the percentage decreases slowly until like 5% or so, then the system would automatically limit the performance and cause lag, which is really irritating as I have to use it for school work. It's almost as if the charger wasn't there at all unless I charged it overnight with the MacBook asleep. Any ideas whats wrong with my MacBook or how I can fix this problem? I have also tried resetting the SMC several times but that didn't help. Here's my Battery Information.

  Model Information:

  Serial Number: D8************NA9

  Manufacturer: SMP

  Device Name: bq20z451

  Pack Lot Code: 0

  PCB Lot Code: 0

  Firmware Version: 406

  Hardware Revision: 000a

  Cell Revision: 162

  Charge Information:

  Charge Remaining (mAh): 878

  Fully Charged: No

  Charging: No

  Full Charge Capacity (mAh): 5531

  Health Information:

  Cycle Count: 589

  Condition: Normal

  Battery Installed: Yes

  Amperage (mA): -55

  Voltage (mV): 7495

System Power Settings:

  AC Power:

  System Sleep Timer (Minutes): 10

  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

  Hibernate Mode: 3

  PrioritizeNetworkReachabilityOverSleep: 0

  Standby Delay: 4200

  Standby Enabled: 1

  Battery Power:

  System Sleep Timer (Minutes): 10

  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

  Hibernate Mode: 3

  Reduce Brightness: Yes

  Standby Delay: 4200

  Standby Enabled: 1

Hardware Configuration:

  UPS Installed: No

AC Charger Information:

  Connected: Yes

  ID: 0x07a1

  Wattage (W): 45

  Family: 0x0085

  Serial Number: 0x004288dd

  Charging: No

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