Normallly, this problem arises due to any of these four issues: Windows Problem, Power Adapter (Charger) Problem, Battery Problem, Laptop’s Internal Motherboard Problem. Since you have already changed the power adapter, we can rule it out. You can check the battery driver: Microsoft ACPI-Compliant Control Method Battery to ensure whether it is causing the issue or not. I would suggesting calling customer care if the laptop is still in warranty period. Generally the battery issues are not entertained by them, but it could be due to motherboard also, so they might find the real cause of the issue.