|Probably most of the laptop batteries are made in China but there are different manufacturing standards and the real cheap ones on ebay can fail pretty quickly. It sounds like you got one of the better ones.|
Dell will have different amperage chargers that will work with your laptop. You might check to see what you have now and get a more powerful one. (The voltage will be the same.) If so, and if you look on ebay as I usually do, I think you're better off with a used Dell OEM than one of the new replacement chargers from China.
As Fingers mentioned, it's usually the battery or charger. I guess another possibility is the charging circuitry inside the laptop but let's not go there for now.
Oh, also check that the battery is fitting tightly and the contacts are clean.