2003 Ford Expedition shuts off

Last night we were driving the car and my battery light came on so I freaked and before I could pull over my car started shutting down. The lights went out I could roll the window up or down then it just died. So we used jumper cables for about ten minutes and it started right up then I left and the same thing happend so we did this till we made it home and my husband used on of his tools to check the battery voltage and its saying 12 volts, So what do you think the problem is? With it being sunday I didn't think I could take it anywhere.