I bought an Amstron replacement battery for my DELL XPS L321X and it takes three days to charge. Is this typical of new? Do off-brand batteries not work well with Dells? What should I do?

 

Are you using the charger that you got with the computer? What is the mAH value of the battery?

And no, three days to charge a battery is not normal.

 

Correct. 3 days is not normal.

Something is either wrong with the battery (generics are usually not good), or the charger is not rated for your laptop/battery. If all was good before the old battery died completely, my first vote would be for the battery being poor quality/bad.