What is a Power Inverter

Power Inverters convert DC current from the 12 volt battery in your car, truck, or RV into 115/120 volt AC current. Power inverters are becoming more and more popular every day. With today's world of mobile electronic devices for both work and leisure, the need to have an AC outlet in our vehicles is vital. This is where power inverters come in. Power Inverters convert the voltage from your vehicle's battery into common "household" power so that you can operate your AC powered devices on-the-go.

Inverters convert your vehicle's battery power "DC" (Direct Current) to "AC" (Alternating Current). They also change the operating voltage from 12-Volts (DC) to 110-Volts (AC) giving you the same power for most appliances, chargers and tools that you would get from plugging them in at home, at the office or on the job site.

Choosing The Right Inverter

Power Inverters are available in two main types: hard-wired "permanent" install and portable cigarette lighter plug styles providing wattages ranging from 100 to 2000 watts. Choosing the right inverter for your needs is not complicated. Just answer a few questions about how you will use the inverter, what devices you will use the inverter for and how much power the devices you will use require. Remember to consider future uses, including additional devices you may wish to add later.

To choose the correct inverter start with how you will use your inverter:
  • How will you use the inverter?
  • Will it be used daily or only occasionally?
  • Can the inverter be hard-wired into your vehicle?
If you are going to occasionally use your inverter, and the devices you wish to power do not exceed 150 watts, consider a "portable" version. This will allow you to quickly plug the inverter in and remove it when not in use. This style also makes it easy to use the inverter in different vehicles. A general rule to follow is any inverter running from your 12-volt power port or cigarette lighter socket cannot power devices requiring over 150 watts.

If you plan to use your inverter daily, or the devices you wish to power require over 150 watts, choose a semi-permanent or hard-wired style inverter. These designs give you more flexibility for higher power output and number of devices you can use at the same time.
  • How many devices will you be using?
  • How many outlets do you need?
  • What is the total wattage of all the devices you will be using?
Different Power Inverters models have 1, 2 or 3 AC outlets. Consider how many devices you will be using at one time and how many outlets will you need at any one time. Then, add the total wattages of ALL the devices you will be using together. This will give you the continuous wattage requirements.

Read your device's owners guide or look on the device itself to determine the operating wattage of the device. Some appliances and tools give you the operating Amperage (Amps) instead of wattage. Use the formulas below to convert Amperage to Wattage (or Wattage to Amperage):

Convert Amps to Watts:

AMPS x VOLTS = WATTS Example: 8.5 Amps x 110 Volts = 935 Watts

Convert Watts to Amps:

WATTS ÷ VOLTS = AMPS Example: 1320 Watts ÷ 110 Volts = 12 Amps

To determine the size vehicle alternator needed to keep up with a specific inverter, you need to convert AC wattage to DC amperage (the value vehicle alternators are measured in) In the example below, you would need a 91 amp alternator to provide a continuous draw of a 1000 watt inverter:

Convert AC Watts to DC Amps:

AC WATTS ÷ 12 x 1.1 = DC AMPS Example: 1000 Watts ÷ 12 = 83.33 x 1.1 = 91.66

Important Information About Waveform Output:

The output waveform of Inverters is referred to as "square wave" or "modified sine wave." Some very sensitive electronic equipment and some medical equipment (listed below) may not operate satisfactorily on "square wave" or "modified sine wave." It is a stepped waveform designed to have characteristics similar to the pure sine wave shape of utility power. A waveform of this nature is suitable for most AC loads (including linear and switching power suppliers used in electronic equipment, transformers and motors).

The problems described above, do not occur with most battery-operated equipment. The vast majority of these items use a separate charger or transformer that plugs into the AC outlet and produces a low voltage output. If the label on your adapter states that it produces a low voltage (AC or DC) output (30 volts or less) Power Inverters will operate the item safely. Some of the following items may not operate properly on a "square wave" inverter. If you have any questions, contact the device's manufacturer.
  • Laser printers, photocopiers, magneto-optical hard drives.
  • Certain laptop computers.
  • Some fluorescent lights with electronic ballasts.
  • Power tools employing "solid state" power or variable speed control.
  • Some battery chargers for cordless tools.
  • Digital clocks with radios.
  • Medical equipment such as oxygen concentrators, nebulizers, and CPAP machines.

Power Inverter Cable size recommendations:

Power Inverter cable gauge based on power inverter size.
Inverter Size Cable Gauge
1000 Watts

#4

1500 Watts

#2

2000 Watts

#1/0

2500 Watts

#1/0

3000 Watts

#3/0

NOTE: These are general minimum size recommendations for inverters that utilize one positive and one negative cable (single cable set) only, and may not be correct for all inverters or applications. Cable size recommendations may vary among inverter brands and models, so check the Owner's Manual for the model you purchase before buying the wire for it.