1998 Hyundai Accent battery drain problem

I have a Hyundia accent 1998 ,manual car and recently it has been playing up.Basically it would`nt start one day so i pushed the car to get it started ,which it did ,but after driving it for a distance the electricals began to fail.At first I noticed the clock dimming out and then the car stopped.I got the roadside service to check it out and he stated it needed a new alternator.So got new alternator put it on .All seemed fine with fully charged battery and reconditioned alternator until I drove it at night for a distance of 8miles.The same condition occured complete battery drain,any Ideas ?