I have a Vostro 1000 laptop and the battery seems to die if I have it unplugged for about 30 minutes or so. Is this normal? Are batteries separate from the "normal" warranties?
Need to be certain I read correct, you say when you unplug can I take it to say when you remove the battery or did you mean when you remove the power adapter.
In either cases I doubt that it shouldn't unless you are using it off course which throws in another equation.
You asked is the battery separate from the warranty this seems to indicate that the machine is under warranty, if so why not have a word with them. Batteries can have manufacturing defects as well as any other part of the machine.
How long the battery lasts on a recharge depends on the capacity of the battery, this may be got from the manufacturers specifications, don't forget the more you use the CD, DVD drives or the more you use the hard drive.... it isn't going to last as long as one thats used just for surfing the Internet say, in other words the battery life depends on the type of workload as well.