battery or electrical

I JUST BOUGHT A 2000 FORD EXPEDITION XLT. WHEN I WAS DRIVING SOMEWHERE ALL OF A SUDDEN MY STEREO WOULD GO ON AND OFF, WHEN IT WOULD GO OFF THE ENTIRE STEREO FACE WOULD SHUT DOWN IT WOULD NO LONGER SHOW THE STATION OR THE TIME. AND THEN IT WOULD GO BACK ON THEN IT COMPLETELY SHUT DOWN. I CONTINUED DRIVING. AND THEN MY (ABS) LIGHT CAME ON AND, MY BATTERY SHOWED AS BEING LOW. I GOT TO WHERE I WAS GOING AND TURNED THE CAR OFF. I TRIED TO RESTART AND IT WOULD NOT START IT JUST MADE A FUNNY CLICKING NOISE. NOTE!!! HEADLIGHT AND INTERIOR LIGHTS STILL WORKED. TOOK BATTERY OUT CHARGED FOR OVER 24 HRS, PUT BACK IN AND THE TRUCK STARTED UP. IT SEEMED FINE FOR THE 20 MIN DRIVE TO MY MOMS HOUSE, BUT ON THE WAY BACK THE RADIO WENT OFF, LIGHTS STARTED DIMMING THROUGH OUT THE TRUCK THE BATTERY GAGE SHOWED LOW AGAIN, THE ABS, THEFT AND AIRBAG LIGHTS CAME ON, WHEN I WOULD STEP ON THE BRAKE THE LIGHTS IN THE TRUCK WOULD GO OUT, AND THEN BACK ON WHEN I WOULD RELEASE THE BRAKE. THE ODOMETER WHICH IS DIGITAL WOULD GO ON AND OFF. THE TRUCK MADE IT HOME WITH ALL OF THAT HAPPENING, BUT WOULD NOT START BACK UP WHEN TURNED OFF. WHEN WE BOUGHT IT THE DEALER SAID THAT SOMEONE LEFT THE LIGHTS ON IN THE VEHICLE OVERNIGHT AND DRAINED THE BATTERY. THEY CHARGED IT FOR A FEW HOURS. WHEN THE CAR FIRST DIED WE TOOK THE BATTERY TO KRAGENS AND THEY SAID THE BATTERY WAS GOOD BECAUSE IT WAS ONLY A YEAR OLD BUT THAT IT WAS DEAD THAT IS WHEN WE TOOK IT AND CHARGED IT OVERNIGHT, BUT THE CAR STILL DID THE SAME THING WHEN WE DROVE IT TO MY MOMS
CAN YOU HELP WE HAVE TO COME UP WITH ALOT OF MONEY DOWN, AND CANT AFFORD TO HAVE ALL THESE THINGS CHECKED OUT, AND THE BATTERY IS NOT COVERED UNDER OUR WARRENTY THAT WE HAVE TO COME UP WITH A 200.00 DED. CAN SOME ONE TELL ME WHAT THEY THINK THE PROBLEM IS. REMEMBER ALL THE LIGHTS AND THE HEADLIGHTS STILL WORK THE TRUCK WILL NOT START THOUGH.
pleeeeeeeeeeeSE HELP

from your description, I would venture a guess as the alternator is going out. And if the battery has been discharged a few times, a new battery will be on the list to replace also. The age of the batteery is not an indication as to the ability of the battery to perform properly. Also the lights will continue to work simply because they do not use as many amperes as the starter and other items. Lights may use 20 amps total, starter uses 150 amps +. Good luck

Replace the battery, sounds like it's the problem, and way cheaper then an alternator, but! run it down and have an electrical charging system check done just to be certain.
but my 1st inclination is a bad battery
good luck
Rick, Ore