Q: I got a brand new battery and my car won't start but will when jumped. What could the problem be?

Hello. If the vehicle has a new battery and if it starts with a jump, then you either have a bad battery terminal connection or the positive battery cable is failing. Most of the time, this will occur if the battery cable has a lot of internal corrosion. This creates high resistance and keeps the power from flowing properly.

If the battery cable end is bad or corroded, this will also occur. I usually do a voltage drop test on both of these to identify the issue. If you are wanting to have this starting problem checked out, consider having a certified mechanic, such as one from YourMechanic, come to your location to determine why the car is not starting correctly.