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Generac GP3500iO - 3000/3500W Open Frame Inverter Generator

The Generac GP3500iO (7128) is a compact and lightweight open frame inverter generator with a rated wattage of 3,000 W and a starting wattage of 3,500 W.

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Generac GP3500iOGenerac GP3500iOGenerac GP3500iO

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 looking for even more independence
  • People occasionally participating in outdoor fairs, festivals or events
  • DIYers who wish to improve their efficiency with tools
  • 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 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 design includes a gasoline-fueled 212 cc Generac OHV 4-stroke engine. With a 120V output, it gives a running wattage of 3,000W and also a peak wattage of 3,500W. In addition, the device is parallel capable (GP3500iO Parallel Kit not included) and thus, can be linked to a similar or compatible unit for added power.

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

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

The GP3500iO produces a clean sine wave: thanks to a <3% Total Harmonic Distortion (THD), your sensitive electronics can be safely plugged in the AC outlets.

Outlets

The control panel provides the upcoming 3 AC outlets:

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

Additionally, it features 2 DC outlets: there's two 5V USB ports with which you may charge electronics, for example mobile phones or tablets, conveniently.

This Generac generator features an L5-30R receptacle, enabling an easy RV connection via an L5-30P to TT-30R adaptor. However, it is still not quite RV ready.

Portability

With its dimensions of L19.3 x W16.9 x H16.4 in, the conventional, open frame design of the Generac GP3500iO offers stability and allows the generator to be raised above ground level. The design is ideal for rough environments and demanding outdoor use.

As the GP3500iO's weight is only 74.3 lbs, it can follow you and your power needs anywhere. Additionally, the generator’s mobility is also improved by its open frame design, as it can be easily grabbed and shifted.

Features

Panel of the Generac GP3500iO

The GP3500iO's control panel

One of the many GP3500iO's features is the data center, included in its control panel, which conveniently provides information on the lifetime run hours and thus, helps you monitor its activity and status.

In addition to this info, several light indicators serve to show you when the generator is on overload, the oil level is too low and the generator is ready.

As far as security is concerned, the generator can be used with a peace of mind, as it features an overload protection (circuit breaker) and an automatic low oil shut-off.

Besides the classic documentation and an owner's manual (opens in a new tab) to get you promptly started, the Generac GP3500iO also comes with some accessories: oil, funnel and tool kit are included.

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 and therefore, can be used 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 inverter generators of similar power (between 2500 and 3500 W).

  • As for its weight, the Generac GP3500iO weighs only 74.3 pounds, making it one of the lighter inverter generators in the 2500-3500 rated wattage category. If weight is your top priority, one of the champions in this power category is the Pulsar PGD40iSCO, weighing just 46 pounds.
  • As far as autonomy is concerned, providing up to 11 hours of runtime with a full tank at a 25% load, the GP3500iO falls into the low end in comparison with other inverters of a comparable power output. If autonomy is your priority, one of the devices of a similar power output with the highest run time is the Champion 200914, 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 not fuel efficient compared to devices of similar output: its estimated fuel consumption stands at 0.22 GPH at a 25% load. If you wish to acquire one of the most gasoline efficient products of this power range, the Energizer eZV3500P, with a fuel consumption of 0.13 GPH could be in your good books.

Price comparison

As you can see from this interactive chart, when compared to other 2500-3500W inverter generators, the Generac GP3500iO is on the cheap side of the price range.

It can therefore be a really good buy if you're looking to acquire a budget generator.

The bottom line

STRENGTHS:
  • Inexpensive
  • 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
Parallel capableYes, cable not included
RV readyNo
FuelGasoline
Engine212 cc Generac OHV 4-stroke
Starting systemRecoil
Warranty3 years
Power
VoltageAC: 120V 60 Hz, DC: 5V
Running watts3,000 W
Starting watts3,500 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%
ComplianceCARB
SecurityLow oil and overload protection
Spark arrestorYes
NeutralFloating
Accessories includedOil, funnel, and tool kit
Other model numbers7128
UPC696471072020

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.

Spec Improvement×

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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 size calculator.
ItemRunning WattsStarting Watts
At homeRefrigerator (energy star)1921192
Hair dryer18001900
Blender400850
Total2392 W3392 W
For campingRadiant heater13001300
RV refrigerator180600
Toaster oven800800
Radio100100
Total2380 W2800 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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Generac GP3500iO
9 Total Score
2 reviews
Add your review
Price
9.5
Value
9.5
Quality
8.5
Performance
8.5

User Reviews

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  1. 4.15
    Price
    90
    Value
    100
    Quality
    70
    Performance
    70

    For the price. Runs close to a honda. Quality is good not perfect.

    + PROS:
    • Large watt inverter for great price. Hour meter is convenient. Fuel gauge on top is useful.
    - CONS:
    • Some parts rattle at certain rpms.
    Helpful(0) Unhelpful(0)You have already voted this
  2. 4.9
    Price
    100
    Value
    90
    Quality
    100
    Performance
    100

    Great generator

    + PROS:
    • Had this generator for over a year. Here hurricanes hits yearly and electricity is out from 1 to 7 days...so far It starts up with ease all the time for me. Easy to maintain. I have a large fridge and 3 other items connected. Runs smoth and no issues. Happy with my generac.
    - CONS:
    • So far no cons that i can see or gone through.
    Helpful(0) Unhelpful(0)You have already voted this

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