Car won't stay charged on 2004 Kia Spectra

My car died on me the other day and I thought it was the battery. I bought a new one and it still doin the same thing. It'll crank when jumped off, but has no power. I push the gas and it won't go anywhere, and shakes until it shuts off. When i turn on the lights the dash lights go dim and the rpm meter drops. Could it be the alternator?

Asked by for the 2004 Kia Spectra
Possibly...check for alternator output at the battery....>13.5V = good alternator...problem is elsewhere...<13.5V = bad alternator...replace alternator, recharge battery, and recheck...
1 more answer
I have a 2003 Kia Spectra with 162,000. It sounds like the regulator that is built into the alternator. Best place is autozone to have those parts checked on the car before replacing. They have remanufactured parts for sale with a lifetime warranty.