The car's alternator does the job of keeping your battery charged and producing the energy to run the electrical accessories in your car. Signs of trouble with your alternator could be a whining noise from the engine as you speed up, or your car's battery light staying on. You may want to check the tension on the alternator belt periodically to make sure it's tight enough. You may also want to regularly check the electrical connections leading to the alternator. If you suspect alternator problems, you may want to take you car to a mechanic as soon as possible to have it tested. A maximum output test as well as a check of charging circuit resistance can often diagnose alternator problems. Contact an auto mechanic or auto parts store in your area for more information on alternators.