Earlier in the week, I was running a errand and was away from my car for maybe 15-20 mins. When I tried to start my car, it wouldn't start. The key was able to turn, buyt the engine wouldn't turn over. After a few minutes of waiting, it worked. Just yesterday, I tried to start it, but no luck. The past few days my car was able to start up, but not as fast as the previous times. Would the problem be my battery? Please help me out here, as I barely have any money right now and need this situation fixed.