A car battery is 12 volts - but actually 12.8 to 13.2 volts, given normal operating conditions.
A car battery is 12 volts. The voltage of a car battery is actually 12.8 to 13.2 volts, given the normal operating conditions of most cars. The battery produces alternating current (ac batteries) and that alternating current has voltage fluctuations. So the voltage of a car battery is not exactly 12 volts. But it is "12-ish" volts. And that's close enough for government work.
A car's alternator has its hands full charging up everything but the car battery.
A car's alternator always provides current to maintain the charge on your vehicle's standard battery, but the charging capacity of a regular car battery is low compared to that of a high-power deep cycle marine/RV type batter. The batteries in RVs are designed for "deep" discharging and recharging, as well as for long periods of non-use (i.e, storage).
Car batteries provide dc voltage, not ac current; they're not designed for frequent full discharge and recharge cycles; their amp-hours rating is relatively small (compared to deep cycle marine or RV batteries); and they don't have enough reserve power to power a lot of electrical accessories for very long.Thomas Edison used direct current for the first electric power transmission systems he invented. The batteries that use DC power supply small electronic appliances and gadgets like laptops, radios, microwaves, and more.
If you've been driving your vehicle and the battery is discharged, the alternator will not produce 100% output when it's trying to recharge the car battery back up to 12 volts; at best, it'll provide about 15% of its normal charging capacity - if that much.
A car battery or any other battery releases DC voltage. It requires some additional circuits if you want to make it AC.
DC electricity is used in a lot of applications. These include:
A DC battery is used to charge batteries, such as the car's battery AC converter.
DC volts are commonly used in electronic equipment that uses direct current (for example televisions, radios, computers and printers). The term "direct current" refers to something that has a constant polarity; it never changes direction. Typically a small AC supplies power to an electronic device; however, the electrical current inside of the device effectively converts the ac power into dc power by using diodes that block reversal of current flow and capacitors which store energy until enough voltage is available to drive a load. So, although the input for these electronics devices might be ac output mains voltage from your home's electrical system, all direct current electronics devices use dc generators internally.
DC batteries are used in fluorescent lightings, such as the lights in your office building or supermarket. The big ballast that you see at the base of each fluorescent light has a bridge rectifier inside of it which allows AC power from an electrical system to be converted into direct current flows to charge up the large capacitors found there, and then that stored energy is released by discharging into the cathodes of all of those little gas-filled tubes inside of every fluorescent light fixture. DC voltage just flows one way -- from high voltage down through a load (such as an incandescent bulb) to ground -- like water flowing downhill in pipes but unlike alternating current which changes direction periodically.
AC power (alternating current) can be converted into a DC generator by using an electronic device called a solid-state diode, of which there are several types. Alternately, an AC adapter can be converted into DC (low voltage) by using a transformer/rectifier combination. A diode (which produces chemical energy) is a simple semiconductor device consisting of two "electrodes" such as n-doped or p-doped silicon, with the cathode being the positive terminal. Two other electrodes are commonly used, one more positive than the cathode, and another less charged than the cathode making for 3 terminals in all. Cathodes are referred to as negative because of their voltage potential when compared to the ground (0 volts); they're not really negative in any other respect. These cathodes and diodes are also used in lithium-ion batteries. This battery (AC or DC) is also called portable battery unit. It is a source of low voltage for a car's electrical system.