Problem with battery or motherboard?

Last few days my Dell Vostro 1200 has a problem. When I run it on just the mains with the battery disconnected, it runs fine, but when I plug in the battery the light on the power adapter goes off and the battery does not charge.

It runs then on the battery till the battery runs out I guess. Have not let the bettery run out yet.

One guy at Dell said its only a battery problem but another said that its a MB issue and that he would sell me an extended warranty for the MB. The extended warranty is 250 USD and I do NOT want to pay that if its only a battery issue.

Any suggestions? I'm in a bit of a hurry as Dell wants a reply to the warranty soon. He said that if I dont take the warranty, and its the MB then the MB itself will be 350 dollars.

 

I'd say this is almost certainly an issue with the motherboard. When the light on the power brick goes out like that, it means there's a sort somewhere, usually in the power circuitry. In this case, it seems like something in your charging mechanism is shot. A lot of more recent Dells seem to be having problems with shorts on the motherboard, so I wouldn't be surprised if your machine was one of these...