Why Doesn't the Car Alternator Generate Electricity?
3 Answers
Car alternator failure to generate electricity may be due to the rotor's magnetic field coil not receiving power or the rotor's claw pole becoming loose. Below are detailed explanations of the causes: Rotor's magnetic field coil not receiving power: The rotor coil has multiple folded layers, and during the insulation varnish dipping process, some varnish may not penetrate to the bottom layer of the coil, leaving gaps between turns in the bottom layer. As the engine speed changes, the bottom layer coil will experience varying centrifugal forces. The frequency of the coil's contraction and expansion determines the number of times the angle between the coil and the lead wire changes. Over time, the lead wires from the magnetic field coil to the slip rings, especially those from the bottom layer coil, can suffer from metal fatigue and break. Solution: Visit a relevant repair shop to replace the rotor coil. Rotor's claw pole becoming loose: If there is slight looseness on the shaft, a gap will form between the inner end face of the claw pole and the magnet end face. The magnetic flux generated by the magnetic field coil will leak through this gap, significantly reducing the magnetic flux in the stator. As a result, the electromotive force induced in the stator coil will also be greatly reduced, preventing the generation of sufficient voltage to charge the battery. Solution: Secure the claw pole to restore power flow.
A non-functioning alternator can be really frustrating. In my experience with customer feedback, about 80% of the issues are caused by the belt. If that rubber belt driving the alternator becomes loose, cracked, or covered in oil, the alternator simply won't spin. The voltage regulator is another delicate component - it tends to fail at the slightest voltage irregularity, causing the entire system to shut down. Worn-out brushes are also quite common since they rub thousands of times daily; once flattened, they lose contact with the rotor. Internal coil shorts are more troublesome and often occur in older vehicles. If you notice flickering headlights or a battery that won't charge fully, check these components immediately - don't wait until you're stranded on the road.
Last time my car suddenly lost all power, and it turned out to be a seized alternator bearing after being towed to the repair shop. The mechanic said long-term dust accumulation can cause the bearing to run dry and eventually seize. Prevention is actually simple: check the belt tension every 50,000 km and test the regulator's output voltage every two years. Another owner had issues with the diode plate—three out of six rectifier diodes burned out, causing complete current chaos. Daily care includes keeping the engine bay dry and paying extra attention to the dashboard battery light after heavy rain. Thinking about it now, preventive maintenance is much more cost-effective than calling a tow truck on the roadside.
