Aside from a dead battery or faulty charging system, the most common electrical issues owners are likely to experience are burned-out light bulbs. After bulbs, though, it's likely potluck: Electrical problems could crop up in many places, from the stereo to an electric motor for a power window or sunroof to an electric fuel pump packing it in. In addition, the cause might be bad wiring, a short, there may be a faulty switch or some other gremlin that's hard to pinpoint.
All batteries, even those using gel instead of electrolyte lose charging capacity as the time passes. The reason for this is that the chemical breakdown of the connections inevitably takes place leading to the deterioration of the plates and loss of the electrolyte. When your vehicle has start up or charging problems, the vehicle troubleshooting procedure should start with a test of the battery. You do that with a visual check followed by a voltage test. If the battery is ok, other components of the electrical system is probably the reason, but battery problems are by far the most likely reason.
Your Cars Alternator. The cars alternator generates electricity which is employed to preserve battery storage charge and to lend a hand in operating the entire the electrical accessories, which includes the ignition and the engine control systems. The cars alternator is belt-driven by the engine and creates an alternating current which is transformed to twelve volts direct current by means of the rectifiers or diode bridge. In contradiction to popular idea, an alternator does not continuously generate electricity. It sequences on and off at the same time as demand goes up and down.
The charging system will normally consist of two major components: An Alternator which actually supplies the necessary electrical current in order to charge the battery, and a Voltage Regulator. The latter insures that the system does not overcharge the battery, and that the correct system voltage is maintained. Most vehicles produced within the last 20-30 years use a voltage regulator which is an integral part of the alternator itself. This article assumes that your vehicle uses this type of alternator.