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Generac GP3500iO Spec Review

The Generac GP3500iO (7128) is a compact and lightweight open frame inverter generator with a rated wattage of 3000 W and a starting wattage of 3500 W.

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Description

Portable generators are a welcome addition to many activities at home, at work, and away. In an emergency, portable generators can provide critical backup power. They make camping and tailgating more comfortable. And contractors appreciate the flexibility portable power brings to the jobsite. (source: Generac (opens in a new tab))

Zoom on the Generac GP3500iO

In a nutshell, the Generac GP3500iO is a compact and lightweight portable inverter generator mostly geared towards:

  • RV travellers who wish to upgrade their experience to another level
  • People occasionally participating in sporting competitions, open-air performances and outdoor festivals
  • Amateur DIY lovers
  • Homeowners in need of an emergency backup power for their essentials
  • Camping and tailgating hobbyists looking for a portable power source

In the sections ahead, the power characteristics, availability of various outlets, the portability, and any additional features of the device shall be discussed, including its emission compliance information.

Power & Run Time

The Generac GP3500iO in use

The Generac GP3500iO

The Generac GP3500iO's engine, 212 cc Generac OHV 4-stroke, fueled by gasoline, can deliver 120V. It provides a running wattage of 3000W and reaches a peak wattage of 3500W. Moreover, since it is parallel capable (GP3500iO Parallel Kit not included), its power may be doubled if linked to a second compatible unit.

The inverter generator features a conventional pull-start mechanism. It features Generac's PowerDial™, an easy-to-use dial with three operation settings.

With a full tank, the GP3500iO can operate for up to 11 hours (fuel consumption around 0.22 GPH), thanks to its fuel capacity of 2.37 gallons.

Delicate electronics can be plugged in an AC outlets safely, as the GP3500iO generates a clean sine wave, reaching a <3% Total Harmonic Disruption (THD).

Outlets

The control panel provides the upcoming 3 AC outlets:

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

It also sports 2 DC outlets: there's two 5V USB ports allowing you to conveniently charge electronics such as mobile phones and tablets.

Even though this Generac generator isn't quite RV Ready, its L5-30R receptacle allows an easy RV connection via an L5-30P to TT-30R adaptor.

Portability

The dimensions of the Generac GP3500iO, which are L19.3 x W16.9 x H16.4 in, and its typical, open frame design provides stability and enables the generator to be raised above ground level. The generator is designed for ideal use outdoors and in rough environments.

With a dry weight of 74.3 lbs, the GP3500iO can easily follow you wherever your power needs are. Furthermore, the open frame of the generator further helps when holding and moving it to a different place.

Features

Panel of the Generac GP3500iO

The GP3500iO's control panel

A digital data center, one of the features of the GP3500iO's control panel, gives you information on the lifetime run hours, and thus, is helpful for the monitoring of its activity and status.

In addition to this info, some light indicators allow you to instantly see if the generator is ready, the generator is overloaded and its oil levels are insufficient.

From a security point of view, the generator is equipped with an automatic low oil shut-off and an overload protection (circuit breaker), giving you a peace of mind during use.

While the standard documentation and an owner's manual (opens in a new tab), helpful for starting the device promptly, come with the Generac GP3500iO, the following accessories are also included: oil, tool kit and funnel.

Emissions

The Generac GP3500iO is CARB-compliant. Therefore, its sale and purchase are permitted in all of the 50 states, including California.

Moreover, it features a spark arrestor, which makes it suitable for use in forested areas.

Product Videos

The Generac GP3500iO versus other generators

The following charts are provided to give you an idea of how some of the key specs of the Generac GP3500iO compare to generators of similar power (between 2500 and 3500 W).

  • Regarding its weight, the Generac GP3500iO only weighs in at 74.3 pounds, which means it's one of the lighter generators in the 2500-3500 rated wattage range. If weight matters to you, one of the champions in this power range is the Generac GP3300i with only 59.5 pounds.
  • Autonomy-wise, with up to 11 hours on a full tank at a 25% load, the GP3500iO is on the low end when compared to other generators of a similar power output. If autonomy is your priority, one of the devices of a similar power output with the highest run time is the Champion 200954, reaching up to 22 hours.
  • 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 0.22 GPH at a 25% load. If you wish to further improve in the area of fuel efficiency, the Energizer eZV3500P, which boasts with a gas consumption of only 0.13 GPH, may be the right generator for you.

Price comparison

As you can see from this interactive chart, when compared to other 2500-3500W generators, the Generac GP3500iO 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
  • Several accessories included
  • Parallel capable
  • Inverter
  • Lightweight (74.3 lbs)
WEAKNESSES:
  • No electric start
  • Relatively low run time
  • Low fuel efficiency

Do you own the Generac GP3500iO and agree (or disagree) with these strengths and weaknesses?

Let us know and write your own review.

Features and Specifications

General
InverterYes
PortableYes
Parallel capableYes, cable not included
RV readyNo
FuelGasoline
Engine212 cc Generac OHV 4-stroke
Starting systemRecoil
Power
VoltageAC: 120V 60 Hz, DC: 5V
Running watts3000 W
Starting watts3500 W
Running amps25 amps
Peak amps29.2 amps
Run time @50% load8 h
Run time @25% load11 h
Features
GFCI outletsNo
Covered outletsNo
Automatic Voltage RegulationInverter
AC outlets
  • 1x Duplex 120V 20A (5-20R)
  • 1x 120V 30A (L5-30R)
DC outlets2x 5V USB port
Data centerLifetime run hours
IndicatorsLow oil, overload and output ready
Fuel tank2.37 gal
Fuel gaugeNo
Misc
Weight74.3 lbs
Approx. dimensions (L x W x H)19.3 x 16.9 x 16.4 in
Noise (lower limit)Unknown
THD< 3%
EmissionsCARB
SecurityLow oil and overload protection
Spark arrestorYes
NeutralFloating
Accessories includedOil, funnel, and tool kit
Warranty3 years
Other model numbers7128

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 Generac

Generac Power Systems is an American based generator and power equipment manufacturer, founded in 1959. As its name suggests, the main focus of Generac are power generators, and other related electric equipment, such as switches, paralleling systems and small engines. The company has several manufacturing facilities based in the US, thus, their products are made in the USA. However, the company provides no information about the origin of their components.

Warranty Information

The Generac GP3500iO 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 Generac generators, please consult Generac's warranty policies (opens in a new tab). Alternatively, you can also contact their Customer Support: 1-888-GENERAC (888-436-3722).

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 generator sizer.
ItemRunning WattsStarting Watts
At homeDish washer15003000
Refrigerator (energy star)1921192
Slow cooker270270
Cell phone charger2020
Total1982 W3482 W
For campingRV AC (11,000 BTU)10101600
RV refrigerator180600
Toaster oven800800
Blender400850
Total2390 W2980 W
For workGrinder14002500
Reciprocating saw730960
Electric fence (25 miles)250250
Total2380 W3480 W
What is the noise rating of the GP3500iO?

Due to the lack of standardization in noise emission measurement, Generac does not provide their units' noise levels.

Does it have an eco mode? (Asked March 19th, 2020)

There is an economy switch that can be put to "ON" when running appliances or equipment that are resistive loads (non-motor starting), such as TVs, lights, laptops, etc.

I want a fuel shut off valve where do I find it (Asked September 24, 2020)

The "OFF" position of the PowerDial Switch stops the engine and shuts off fuel flow.

This unit is a inverter generator ,why do you say it isn't for RV . Is it good for Small 24 ft. Travel trailer? 1 small roof air conditioner? And tv outlets few other things ? (Asked March 20, 2021)

We did not say it's not for RV. We said it's not RV-Ready, since it does not have a TT-30R outlet. This does not mean that the unit is not suitable for an RV. You may read our definition of RV-Ready and use our wattage calculator to estimate your appliances power needs.

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