Why won't a car start that has a new charged battery without being jump started?

Answer 1

From your question, I assume the car will not start on the new battery alone, but will start if you add a "jump" to it. The bushings inside the starter may be worn and the starter is dragging and not spinning fast enough to start the engine unless it has that extra "jump". Remove the starter and inspect it - sometimes grime and grit will get inside and prevent enough power to get to the armature to make it spin fast enough, Also test the starter by clamping the positive jumper cable on the post where the battery cable attaches and the negative on the "ear" of the starter where the bolts go through that attach it to the engine. Before you attach the negative cable, make sure the starter is secure because it will "recoil". If the starter spins easily, the problem lies elsewhere. If it is hard to spin, the bushings are worn or it may have a lot of dirt and grime inside. If you hear a definite metal-on-metal grinding noise, the bushings are badly worn.