sut had an engine conversion done, ike yesterday, 2.0 zetec

been out in it all day did about 80 miles and was fine, until tonight while i was driving and the battery died, the car was jumpstarted first but lost power again shortly after. it also was bumpstarted several times during the night, but lost power again within a few minutes. does anyone know what could cause this, and what coule be the resolution? im hoping that it gets to work tomorrow morning so i can fix this