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Firman W03661OF - 3650/4500W Open Frame Inverter Generator

The Firman W03661OF is a portable open frame inverter generator with a rated wattage of 3,650 W and a starting wattage of 4,500 W. (Read full specs)

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Description

Zoom on the Firman W03661OF

In summary, the Firman W03661OF is a portable inverter generator especially useful for:

  • RV travellers looking for even more independence
  • People occasionally participating in sporting competitions, open-air performances and outdoor festivals
  • Homeowners who want to be sure of their ability to power their fridges, cooking tools, heating and lighting equipment during power failures
  • Tailgating and campground aficionados with the desire of enjoying power anywhere they go

In the following paragraphs, we shall explore the power characteristics, available outlets, portability, and any additional features of the device.

Power & Run Time

The Firman W03661OF in use

The Firman W03661OF

Running on gasoline, the Firman W03661OF operates with a 208 cc OHV 4-stroke engine, delivering 120V, with a running wattage of 3,650W and a peak wattage of 4,500W. Additionally, as the generator is parallel capable (parallel kit not included), it can be linked to a second unit for more power.

At a noise rating of 69 dBA (less noisy than background music), the inverter generator is started via a classic hand-operated recoil starting mechanism.

With its 6 gallons fuel tank, the W03661OF can operate for up to 25 hours when fully fueled (with fuel usage averaging around 0.24 GPH).

With a <3% Total Harmonic Distortion (THD), the W03661OF delivers a clean sine wave—essential for safeguarding your delicate electronics when plugged into its AC outlets.

Outlets

The control panel features 4 AC outlets as follows:

Duplex 120V 20A (5-20R)
120V 30A (L5-30R) receptacle
120V 50A (14-50R) receptacle

Additionally, it offers 3 DC outlets: there's two 5V USB ports (USB-A) designed for hassle-free charging of various electronic devices such as smartphones and tablets, ensuring uninterrupted usage and a 12V 8A (cigarette lighter style) receptacle providing easy battery charging capabilities.

For RV owners with a 50-amp service, this Firman unit is RV-ready, boasting a 14-50R outlet.

Important note: The 14-50R outlet is normally 120/240V. However, this unit does not produce 240V. This outlet is here for your convenience, but should only be used to power 120V appliances. In addition, since the generator provides a maximum of 3650 running watts, it will not be possible to draw the full 50 amps from the outlet.

Portability

Measuring L24.5 x W24.1 x H23 in, the classic open frame build of the Firman W03661OF delivers stability and easy maintenance access to components, facilitating air circulation. The design is ideal for rough environments and demanding outdoor use.

Despite its weight of 106 lbs, the generator is considered 'portable,' signifying its capability to be moved, albeit its heaviness may hinder easy transport. Nevertheless, it can still be moved quite conveniently with the help of its set of wheels (⌀9") and its folding handle, once it is placed on the ground.

Features

Panel of the Firman W03661OF

The W03661OF's control panel

The control panel of the W03661OF includes a convenient meter, showing voltage, frequency, and lifetime hours metrics, helpful for the monitoring of its status and activity.

In addition to this info, the device’s light indicators will display if the generator is ready, the generator is on overload and the oil level is too low.

The inverter generator allows for a quick, easy and convenient assessment of its gas level, as it is equipped with a built-in fuel gauge.

As for its security measures, the device features an automatic low oil shut-off and an overload protection (circuit breaker), letting you use it with a peace of mind.

The W03661OF also benefits from Firman’s CO Alert carbon monoxide shutdown, which automatically shuts down the engine when harmful levels of carbon monoxide accumulate around the generator or a CO Alert fault occurs.

Apart from the typical documentation and an owner's manual (opens in a new tab), which lets you start it right away, the Firman W03661OF also is packed along with the following accessories: tool kit, battery charging cables, oil, RV adapter and funnel.

The Firman W03661OF versus other generators

The following charts are provided to give you an idea of how some of the key specs of the Firman W03661OF compare to inverter generators of similar power (between 3500 and 4500 W).

  • Having a dry weight of 106 lbs, the Firman W03661OF belongs in the expected weight range for inverter generators which produce 3500 to 4500 rated watts. If weight matters to you, one of the champions in this power range is the Genmax GM4600iAEFIC with only 58.4 pounds.
  • When compared to devices able to produce a similar running wattage, this inverter generator and its lowest emitted noise of 69 dBA is on the noisier side. If you wish to prioritize minimal noise, the Westinghouse iGen4500DF stands out as one of the quietest options among generators of similar power, with a rating of 52 dBA.
  • With up to 25 hours of runtime at 25% load, the W03661OF provides a one of the highest run times when compared to similarly powerful inverters.
  • Even though run times are undoubtedly important, they are dependent on the fuel capacity to a large extent. For a more wholesome picture, we must take into consideration the fuel consumption of the generator. This inverter generator is rather wasteful, compared to other devices within the aforementioned output range, when it comes to gasoline consumption, as it reaches roughly 0.24 GPH at a 25% load. If minimizing fuel usage is one of your key priorities, the Champion 200988 is one of the most efficient devices with similar power output, with a gasoline consumption of only 0.16 gallons per hour.

Price comparison

As you can see from these interactive charts, when compared to other 3500-4500W inverter generators, the Firman W03661OF is on the average side of the price range.

Therefore, this generator nicely fits in the expected budget for this kind of product.

The bottom line

STRENGTHS:
  • In the expected price range
  • CO Alert technology
  • Several accessories included
  • RV adapter included
  • Parallel capable
  • Inverter
  • High run time
AVERAGE SPECS:
  • Decent weight (106 lbs)
WEAKNESSES:
  • No 240V output
  • No electric start
  • On the noisy side (69 dBA)
  • Low fuel efficiency

Do you own the Firman W03661OF and agree (or disagree) with these strengths and weaknesses?

Let us know and write your own review.

Features and Specifications

General
InverterYes
Parallel capableYes, cable not included
RV readyNo
FuelGasoline
Engine208 cc OHV 4-stroke
Starting systemRecoil
Warranty3 years
Power
VoltageAC: 120V 60 Hz, DC: 12V
Running watts3,650 W
Starting watts4,500 W
Running amps30.4 amps
Peak amps37.5 amps
Run time @50% loadUnknown
Run time @25% load25 h
Features
GFCI outletsNo
Covered outletsYes
Automatic Voltage RegulationInverter
AC outlets
  • 1x Duplex 120V 20A (5-20R)
  • 1x 120V 30A (L5-30R)
  • 1x 120V 50A (14-50R)
DC outlets2x 5V USB port (USB-A)
1x 12V 8A (cigarette lighter style)
Data centerVFT
IndicatorsLow oil, overload and output ready
Fuel tankSteel, 6 gal
Fuel gaugeYes
Misc
Weight106 lbs
Approx. dimensions (L x W x H)24.5 x 24.1 x 23 in
Noise (lower limit)69 dBA
THD< 3%
ComplianceCARB, EPA
SecurityLow oil and overload protection, CO monitoring
Spark arrestorYes
NeutralFloating
Accessories includedOil, funnel, tool kit, RV adapter, battery charging cables, and wheel kit
Country of originChina
SeriesWhisper
UPC840876136614

Unlike many websites, we did our best to research each of the specs above. That being said, we are not immune to making the occasional mistake or omission. Should you notice any missing or incorrect values, don't hesitate to suggest improvements so we can address the issue.

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About FIRMAN Power Equipment

Founded in 1999, Firman Power Equipment is a company with a short, but established history in the power equipment industry. Based in Arizona, the company offers an immense range of products, including power tools, automotive equipment, storage utilities, work wear, but most importantly, a wide selection of generators of all sizes, designs and outputs. Interestingly, Firman is a wholly owned subsidiary of the China National Machinery Industry Corporation - a somewhat well renowned company in China and acts as a de facto distributor of their products in the US.

Warranty Information

The Firman W03661OF is covered under a warranty for up to 3 years. This warranty may be limited and may not cover all parts of the generator.
For more information about the warranty of Firman generators, please consult Firman's warranty policies (opens in a new tab). Alternatively, you can also contact their Customer Support: 1-844-FIRMAN1 (844-347-6261).

Questions & Answers

What can it power?
Examples of items that can be simultaneously powered.
The examples below are based on a maximum load of 80% and estimated wattages. For a more accurate estimation, use our wattage calculator.
ItemRunning WattsStarting Watts
At homeAC (10,000 BTU)15002200
Refrigerator (energy star)1921192
Vacuum cleaner10751175
Laptop150150
Total2917 W3917 W
For campingRV AC (11,000 BTU)10101600
RV refrigerator180600
Electric grill16501650
Set of 5 LED light bulbs5555
Cell phone charger2020
Total2915 W3505 W
For workGrinder14002500
Demolition hammer12601260
Drain cleaner250250
Total2910 W4010 W

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