Plugged In Not Charging

Recently the battery on my XPS M1530 (6 months old) stopped charging when plugged in. Message on the bottom right of the desktop (battery indicator) said "plugged in not charging". Battery was not getting charged. Laptop would run fine when plugged in but would not run at all when on battery power (cos battery had zero charge).

Anyway called Dell Tech.  After running various tests the tech could not find any thing wrong so he said "most probably the charger" and sent one out. Received it... still same problem.... called again.. Same tests and as I already had a new charger.. he now said "most probably the battery" and sent out one. Received it.. same problem still..   By the way both those calls were answered by a tech in North America.

So.. Called again..this time connected to India...same tests again.. but this time the tech said update BIOS. So I did that... and what do you know.. problem solved..  !! :)

When tests were done on first two calls, the BIOS showed the battery and indicated zero charge but operating normally and the charger was not showing. Said something like unknown device attached.

Now even though the battery is charging and everything works fine, the BIOS now shows as No battery connected and charger still shows as unknown device attached.

Is this normal or should I be calling tech support again ?

My only worry is that the system is still under warranty and I do not want to find out this is not normal and I have some problems connected to this issue after my warranty has expired !

Also seeing that I have a new battery and charger I think I will keep original ones as they are fine and just pay for them ($80). From previous laptops I know teh charger cord can be finnicky when rolled up to carry in laptop bag. All the rolling up and unrolling of the cord tends to make it stop working.  

Thanks