Latitude 7480 battery

Hello !

I have been facing a weird issue with my Dell Latitude 7480. I bought it recently and upgraded it to 16gb ram and 512gb ssd and put in a new battery. The issue is that the battery duration is okay, fine, like laptop runs for good 3-3.5 hours under load on full battery but the problem is that battery instantly drains to 6% when the battery reaches 30%. I have seen many several posts about this issue, most suggest to change the battery to fix it which i did change to new one and most said that to do some software tweak like changing power options etc. I did that as well, bios shows that battery is in excellent condition, dell power manager app shows the battery is in excellent health. I dont understand then why it's acting like that. I would be thankful if anyone could solve my issue.