Should I be worried about Lumia 830 battery drain?

[ArunabhD]

Hi Everyone,

I needed some expert help on my 830 that I bought couple of months back. I love everything about it except the battery. With low to medium usage it barely lasts a day while during heavy usage it discharges at close to 12%-15% per hour.
Tonight It dropped by a whopping 38% in two hours and I came searching online.I was using Whatsapp heavily and 10 minutes of FB/browsing. Phone was on 3g mode with data off. Pls see attached





I am on win 8.1 and most background tasks except Whatsapp are turned off. One of my friend gets excellent battery backup on his 830 so we exchanged batteries for a couple of days but it did not help. Changing panels too did not have any perceptible difference. One thing to note is I bought a white 830 and currently using with an Orange panel.

Could someone please help me:
1) Identify potential issues with the battery back up;

2) Suggest if a hard reset would be the solution. I did it last weekend but with a restore of an old back up. If restore is not advisable will I get my contacts list after I login with my outlook.com account because that is what I pretty much care.

Thanks in advance.