1984 Nissan 200SX Car trouble

1984 Nissan 200SX 4 cyl Two Wheel Drive Manual

I was driving a friend home, and when i was on my way home back, a 20 mile trip, it felt as if the car was missing, and at first it was just doing it here and there, ive had a different car miss and it was kinda minor problem, so i didnt think to much of it. But then it felt like it was missing harder and alot more and more, as if it was jolting/jumping. I had managed to make it in my housing edition and then it was still missing and then the lights started to flicker and then the car just died. I can start the car back up, but if i put it into gear the car shakes and lights flash and then die again withing 2 feet of travel distance or so.
I think this might be an alternator problem but yet when i start the car it charges the battery. how ever it doesnt charge past 12 volts, but never have i actually scene the battery past 12 volts in the time ive owned this car, i'm borrowing the car from a friend until i repair my old car. Luckily he has another car as well as mine is almost fixed.