Cars generally make clicking noises without starting when their batteries die. Sometimes lights and other accessories turn on in cars with ailing batteries, but the batteries do not provide sufficient power to enable vehicles to turn on. Engines crank slowly but do not turn on in cars with low-powered batteries.
To start, car engines must turn over quickly, which triggers the ignition system. Upon turning the key, the battery supplies power to various components of the car, including the starter. The starter connects to the electrical system and ultimately helps the car run. Engines that crank slowly upon turning the key indicate the battery lacks the power for starting the car. Engines might crank for some time but never fully turn over.
Sometimes cars with dead batteries start briefly with a jump start, using the help of connecting cables and a healthy helping vehicle. However, batteries must be replaced soon after the jump start as those starts only provide a temporary fix. While aging batteries often cause clicking and cranking, other less-common electrical problems produce similar symptoms too.
Bad ignition switches or failing starter sensors prevent cars from turning on. Bad wiring and improper electrical connections in the car might cause clicking and cranking engines too. After replacing a battery, provided that is the problem, cars ideally receive electrical system checks from mechanics.