What's the reason when the battery has power but the starter motor doesn't respond?
2 Answers
The reasons why the starter motor doesn't respond when the battery has power include CPU and control circuit failure, battery depletion, and damage to the igniter or pulse generator. Below is an extended introduction: 1. Car starting requirements: It must generate enough voltage to break down the spark plug gap. The voltage required to break down the spark plug electrodes and produce a spark is called the breakdown voltage. The secondary voltage generated by the ignition system must be higher than the breakdown voltage for the spark plug to fire. 2. Factors affecting the breakdown voltage: 1) Spark plug electrode gap and shape: The larger the spark plug electrode gap, the higher the breakdown voltage; sharp edges on the electrodes require lower breakdown voltage. 2) Pressure and temperature of the gas mixture in the cylinder: Higher pressure and lower temperature of the mixture result in higher breakdown voltage. 3) Electrode temperature: Higher spark plug electrode temperature reduces the gas density around the electrodes, leading to lower breakdown voltage.
I sometimes encounter this issue too, where the battery appears to have power but the motor doesn't make a sound at all. It could be due to faults in several key components: the starter motor itself, such as worn-out carbon brushes getting stuck or a seized bearing; connection circuit problems, especially a faulty relay preventing high current from passing through; interference from the ignition switch or steering wheel lock, blocking the signal from reaching the motor; corroded or loose battery terminals, which may show voltage but can't deliver high current; or a poor ground connection disrupting the entire circuit. I recommend starting with simple checks—clean the battery terminals and tighten them, try replacing a fuse, and if that doesn't work, use a multimeter to test if the relay is functioning. Avoid repeatedly turning the key to prevent damaging more components. If necessary, have a professional mechanic use specialized equipment for diagnosis.
