12-volt (AC) appliances are designed to make life on the road easier. 12-volt appliances are designed for Trucker's and Travelers alike. All 12-Volt Appliances will plug into a standard 12-volt AC cigarette lighter receptacle.
While most 12-volt appliances will work in a car, 12-Volt appliances were designed for Trucks and RVs which have special 12-Volt receptacles designed to work from dedicated batteries and for higher amperage needs. Be sure to verify your power requirements and availability with your vehicle manufacturer and appliance/device manufacturer when using a 12-volt appliance.
The 120 volt outlet in your home can put out as much as 15 amps. 120 volts x 15 amps = 1800 watts. Now, the 12 volt outlet in your vehicle can also put out 15 amps of power. However, 12 volts x 15 amps = 180, now we only have 180 watts of power; this why your 12-volt appliances take longer to produce the same results as your home appliances.
For electrical devices that utilize alternating current (AC) to run or to be charged; such as MP3 players, laptops, household appliances, TV sets, video games and mobile phone chargers, a power inverter can operate them or supply a charging outlet. Power inverters convert direct current (DC), the power that comes from a car battery, into alternating current (AC), the kind of power supplied to your home.
Simple conversion formulas:
Amps x Volts = Watts
Watts ÷ Volts = Amps
AC = DC ÷ 0.636
AC - Alternating Current
DC - Direct Current
0.636 – Constant