You got a replacement battery? I called DELL about the battery which lasted just over a year and they wouldnt replace it. I got the extended warranty. If you read the fine line on warranty it does not cover battery. I think Dell knows this and specifically excluded battery on the extended warranty.
My other DELL only lasted about a year on the battery.
I think mine was actually just under the year mark, come to think of it. Yes, they did replace the battery. Very nice of them. But not nice enough to keep me as a permanent customer. I go where the good stuff is. Typing this reply on an iMac, have a Macbook Air, now using a Lenovo IdeaPad U330 as my main notebook.