Understanding Inverters and How-to Select one that is right for you

Understanding Inverters and How-to Select one that is right for you

Justin G1/ 7/21

by Justin Gray

We often find people are overwhelmed when it comes to learning about and selecting the right power for their needs. This blog will break it down in small, easily digestible pieces to help you find what is right for you.

Answer These 5 Q's:


1- What appliance(s) do you need to power? What is the Wattage of each appliance?

2- Do the appliances need to run at the same time? If so, add the wattages together (wattage is usually printed on the device). If you are only running one appliance at a time, which appliance uses the most wattage? (Some motorized tools and appliances are rated in Amps at a rated Voltage. To calculate Watt from Amps, Multiply Amps by Voltage. For example, a refrigerator operates at 6.0 Amps at 115 Volts. So 6.0 X 115 = 690 Watts)

3- What is the Peak Surge of the appliance (if there is one, it is usually expressed in Amps(A) )?

4- Do you need a Pure Sine Wave or Modified Sine Wave? If unsure, see the definition in the glossary below.

5- Add 20% to the total wattage you need. (if you calculate 100 watts required, select a 120 watt inverter (100x0.20=20 so, 100w+20w=120w))

6- Select an Inverter here that fits your needs! (Yes, it really is that easy!)
All Wagan Tech Inverters



Glossary of Common Terms:

ac outlet

AC (Alternating Current)
AC is an electric current in which the flow of electric charge periodically reverses direction. This is the current type commonly found in buildings and residential homes (the wall outlet) - In the US, it is commonly found between 110-120V AC. 

Amperage (Amperes), A. (Current)
Amperage is the volume of electricity that flows in one second. Amps are the units that describe current flow. Batteries are rated in Amp Hours. Circuit Breakers and fuses are rated for the maximum amount of Amps they can handle before they open to protect the circuit.

wagan tech battery

Batteries store energy. Primary batteries are discarded after they are depleted of energy (flashlight batteries, or cells). Secondary Batteries are rechargeable and are used until they no longer store enough energy to be useful.

Batteries are made of identical Cells. The greater number of cells in series, the higher the voltage (electric pressure) of the battery. Vehicle batteries that are rated at 12 volts (technically up to 13.2 Volts) have six 2.2 Volt cells in series (6 x 2.2V = 13.2V).

Battery capacity is expressed as Amp Hours (Ah), most commonly at the 20 hour rate. A typical 12V automobile battery has 50-80 Amp Hours (Ah) capacity.

For a 12 volt battery, 10.0 volts is considered a depleted battery and should be fully charged as soon as possible.

Battery Size
For smaller inverters less than 200 watts, a normal automobile size battery is sufficient to power the inverter for short durations with the vehicle off. However, you should run the vehicle for 10 minutes for every 30 minutes of use (depending on your battery/inverter size and the load) to ensure that you do not discharge the battery too much.
If using repeatedly or deeply discharging the battery, it is recommended that you select a marine type deep cycle battery because they can handle the constant cycling and charge/discharge rates without shortening the battery’s lifespan.

cable gauge awg

Cable Size (Gauge)
For wiring directly to the battery, you must use the appropriate size cables to avoid a hazardous condition. Inverter to Battery cable determination depends on two factors: overall length and the maximum sustained current (Amps) the cable has to carry. Cable Gauge is the diameter of the copper conductor. We have an outstanding blog on cables here.

DC current flow

DC (Direct Current)
DC is an electric current in which the flow of electricity flow is always in the same direction. This is the current type found in batteries, power supplies (PPS), car alternators (Cigarette Lighter Socket), and solar cells.


DC Socket Limitations

In relation to the use of inverters in vehicles, the DC socket (aka: Cigarette Lighter Plug, Cigarette Lighter Receptacle, DC outlet) is generally limited to 15A; this equates to a maximum available wattage of 180 watts (15A x 12V= 180W). There are other considerations to be made in the equation, but as a general rule you will not get more than 180 watts from a DC Socket.

12V DC
If the device you intend to power is at or above 180 watts, you will need to have a capable inverter wired directly to the battery. (See Current and Voltage)
Another good reason to wire the inverter to the battery is so you do not have the ignition on to operate the DC accessory socket.


Efficiency measures output energy compared to input energy as a percentage. All Wagan power inverters have efficiencies that are approximately 90 percent. Inverters are most efficient when they operate closer to its maximum output. Most of the energy lost during power conversion from DC to AC becomes heat that the inverter’s fan dissipates.

wagan tech fuse

All power sources are required to be protected from over-current damage. All vehicular or stationary battery installations require fuse(s) or airtight circuit breaker to keep batteries from exploding should there be a battery cable short circuit. Battery Protection fuses must not make a spark if they blow. The Amps or Current Rating of the fuse or breaker should be at least 20 percent greater than required during regular operation. All battery Protection Fuses must be located within one foot of the Positive Battery Terminal. Marine (vessel) battery Protection Fuses are located within eight inches of the Positive battery Terminal.

high output terminals

High Output Terminals
Provide the Neutral to Ground Bond (connection) and provide a connection to higher power appliances that require greater than 15 Amps. High Output Terminals (if present) are located on inverter front panels.

Modified Sine Waves
(MSW) Inverters are less expensive to produce compared to comparable wattage PSW Inverters.

The benefits of the MSW are: it will operate most electronics without problems, they are cheaper, and efficient for most needs. However, some electronics and appliances simply will not operate on a Modified Sine Wave. Sample items that may not operate on an MSW inverter are: some laptops, printers, some coffee makers, dimmers, digital clocks, fluorescent lights, fans, and some microwaves. MSWs can also over-heat some devices and potentially lead to the device’s shortened lifespan.



Neutral to Ground Bond
Wiring to US standard AC outlets have three conductors: Hot (black), Neutral (white) and Ground (green or bare copper). Hot and Neutral deliver power to the connected appliance. The Ground (round pin) is for personnel safety and to insure fuses blow if there is a short circuit. All AC sources such as portable generators, commercial power, and Wagan larger inverters provide a connection from Neutral to Ground, to be compliant with US electric standards. All Wagan 120 Volt Inverters that have High Output Terminals provide the Neutral to Ground bond. High output Terminals allow Wagan Inverters to power standard electric panels during commercial power outages. Check with Wagan Customer Support for details.

No Load Current Draw
No Load Current Draw (aka: No Load Current, No Load Power, Idle Draw, Etc.) is how much electricity that the Inverter “consumes” while connected to a power source (such as a battery), but without anything being plugged into the Inverter itself. This is generally a very low Amperage number between 0.1A-2.5A.

Operating Environments
The ideal operating environment for Inverters is one that is protected yet is free of dust, flammables, and moisture, but still provides airflow with ample air space for the inverter. Inverters need an environment that is uncluttered and can provide enough air to keep it running cool and efficiently. In a drawer, near a gas can, or piled under gear IS NOT a safe operating environment for an inverter. 
Inverters also need to be secured. Large Inverters should not be left unsecured in a vehicle due to the likelihood of them becoming a projectile in the event of a crash. Household Inverters should be mounted to avoid tripping hazards, bug intrusion, and moisture collection.

Peak Surge
Peak surge is usually found in devices with electric motors and is the amount of watts it takes for the device to cycle during operation and/or at start-up. After the start-up surge, the current drops and levels out. Microwaves tend to cycle peak surges during operation, while devices such as air compressors and water pumps reach a peak surge only at start-up. Start-up Peak Surges can be up to 5x the normal operating wattage. Most Start-up peak surges are less than one-second. Also see, Soft-Start.


Pure Sine Waves
(PSW) Inverters allow electronics to run cooler (less cycling), cleaner, and with less noise. PSW is the output form that comes from the AC wall outlet in your house and is the most stable. The benefits are numerous: Clean, efficient, can operate all electronic devices, and is a true Sine waveform. The downside to PSWs is that they are more expensive to produce than a comparable wattage MSW Inverter.

Most Wagan Pure Sine Wave inverters have a feature called Soft-Start. During no-load conditions, the inverter output voltage is reduced. As soon as an appliance is turned on, the voltage quickly ramps up to full voltage. Soft-Start avoids large peak wattage surges as motors and incandescent lamps start-up. Soft-Start can also extend the life of incandescent lamps by reducing failure from thermal shock (bulbs usually fail when they are turned on).

truerated power

TrueRated Power
TrueRated Power is Wagan Tech’s coined term for truth in advertising and performance. While actual output wattage of competitor’s inverters varies greatly, Wagan Tech inverters help consumers to understand and trust that the number printed on the inverter is the actual continuous output of the device. Nearly all of Wagan Tech’s Inverters feature TrueRated Power. Simply put, our inverters are tested at full load and will sustain that load continuously for 24 hours at the wattage printed on the inverter. For example, our Elite 400 Watt Pro Inverter will run for 24 hours straight with a 400 Watt load.

Watts, Wattage, W (Power)
A Watt is a derived unit of power that is expressed as the rate of energy conversion/transfer with respect to time. A watt is not a unit of time, but a unit of Power. To calculate wattage, multiply amperages by voltage: (Amps x Volts = Watts)


Wattage, Amperage, and Voltage Simplified
As an example, let’s look at Wattage, Amperage, and Voltage as if they were water in a common residential home. Electricity is the "water" in your home plumbing. Voltage would be the water pressure and amperage is the quantity of water flowing past a given point measured in seconds. A small pipe would restrict the water flow at a given pressure, while a large pipe would flow more freely at the same given pressure; the pipes would be considered to be the amount of electrical resistance in the system. The higher the electrical resistance of a device, the lower its current will be with resistance being dependent on the diameter of the wires.

Voltage is a unit of electric “pressure”. Voltage is essentially the difference in electrical charge between two points. The greater the voltage difference, the greater the flow of electrical current if all other factors remain the same in a closed circuit. Batteries are described in terms of voltage. Batteries that have more cells than others have higher voltage. (see Batteries). Another term for voltage is EMF (Electro-Motive Force).


Built-in Safety Protections

> Low Battery:
Low-Battery protections are in place to prevent your power supply (usually batteries) from discharging too deeply thus irreparably damaging them. Usually an audible alarm will sound and the inverter will shut down when the battery voltage drops past 10.0V (generally within ±0.5V depending on the inverter model). This is important because most 12V vehicles can start on 7.5 Volts. Discharged batteries should be charged as soon as possible.

> Over-Heating:
All Wagan Tech inverters have a temperature sensor built-in to them that will shut the inverter down if the internal temperature of the device exceeds a pre-set threshold. This is to ensure the safety of the user and to stop the inverter from over-heating and damaging itself. This is why most inverters come pre-installed with a thermal cooling fan.

> Over-Load:
Inverter over-loading occurs when a device or a set of devices surpasses the available wattage from the inverter.
Example: If your inverter is rated at 1,000 continuous watts and you plug in a 500 watt appliance, the inverter will run just fine with 500 watts to spare. Let’s say you then plug in a 400 watt device; now the 1,000 watt inverter is operating at a load of 900 watts. If you then attempt to plug in another device that requires 300 watts, the inverter will show an over-load condition and shut down (since the total load is now at 1,200 watts).

> Reverse Polarity:
A reverse polarity condition occurs when the power supply (usually a battery or bank of batteries) polarities are reversed with the inverter. Example: The Positive terminal of the battery is connected to the Negative terminal on the inverter and the Negative terminal of the battery is connected to the Positive terminal on the inverter.
Reverse Polarity often damages equipment; always ensure connections and polarities are correct before powering a DC appliance

> Short-Circuit:
A short circuit is an electrical circuit (usually unintended) that allows excessive current to flow. Fuses and Circuit breakers are used to protect against these flows.



Certification logo

CE marking is a mandatory conformity marking for certain products sold within the European Economic Area (EEA) since 1985. The CE marking is also found on products sold outside the EEA that are manufactured in, or designed to be sold in, the EEA.


Certification logo

CSA International (Canadian Standards Association), a member of the CSA Group, is a provider of product testing and certification services for electrical, mechanical, plumbing, gas and a variety of other products. Recognized in the U.S., Canada and around the world, CSA's marks appear on billions of products worldwide.



Certification logo

The ETL Mark is proof of product compliance to North American safety standards. Authorities Having Jurisdiction (AHJs) and code officials across the US and Canada accept the ETL Listed Mark as proof of product compliance to published industry standards.



Certification logo

The FCC Declaration of Conformity or the FCC label or the FCC mark is a certification mark employed on electronic products manufactured or sold in the United States which certifies that the electromagnetic interference from the device is under limits approved by the Federal Communications Commission.


Certification logo

RoHS is the acronym for Restriction of Hazardous Substances. RoHS, also known as Directive 2002/95/EC, originated in the European Union and restricts the use of specific hazardous materials found in electrical and electronic products.




Certification logo

UL & UL (c):
Safety certification is the process of assessing the compliance of products to recognized safety requirements. This certification most frequently addresses electrical safety, fire risks and other product hazards and can include other attributes, all focused on making products safer to use. Underwriters Laboratories of Canada is an independent product safety testing, certification and inspection organization.



Need more help?
If you are still unsure which model is right for you, feel free to call our Customer Service Department and one of our team members will gladly find the Inverter that fits your needs! Wagan Tech Customer Service 1.800.231.5806

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