Generac GP3500iO Portable Generator Review

If you are looking for an inverter generator to suit your need for reliable power, then you need nothing except Generac GP3500iO Generator. Not only are the technological features advanced enough to facilitate their use, but they are also useful. You can now better your experience of generating portable power with this equipment.

Generac GP3500iO Generator weight

The heart of the Generac GP3500iO is the Generac 212cc four-stroke OHV engine that runs on gasoline. With 120V output, it offers 3000W operating power and 3500W peak power. As it is parallel compatible, this power can be doubled when connected to another similar device or is supported.

With a fuel capacity of 2.37 gallons, the GP3500iO can run for up to 11 hours on a full tank.

Comparison Between Generac GP3500iO and Others

Generac 7127

Ultra Quiet
  • Power: 3000 watts / 3500 watts
  • Engine: 212cc
  • Run-time: 12 Hours
  • Noise Level: 60 dBA
  • Outlets: 2 – 120V 20A, 120V 30A RV, 2 USB Port
  • Fuel Tank: 1 Gallon
  • Size: 23.7 x 18 x 21.7 Inches
  • Weight: 109.1 Pounds
  • Parallel Ready: Yes
  • Warranty: 3-Year
  • User Rating: – 4.60 Out of 5 – 3.9K+ Customers
  • Expert Score: – 4.60 Out of 5

Champion 3400

Dual Fuel Generator
  • Power: 3100 Watts / 3400 Watts
  • Engine: 192cc
  • Run-time: 7.5 Hours (Gas), Up to 14.5 Hours (Propane)
  • Noise Level: 59 dBA
  • Outlets: 2 – 120V 20A, 120V 30A RV, 12V DC outlet with dual USB Adapter
  • Fuel Tank: 1.6 Gallons
  • Size: 25.1 x 17.3 x 18.3 Inches
  • Weight: 95.7 Pounds
  • Parallel Ready: Yes
  • Warranty: 3-Year
  • User Rating: – 4.70 Out of 5 – 1.9K Customers
  • Expert Score: – 4.80 Out of 5


  • Power: 2900 watts / 3200 watts
  • Engine: 193cc
  • Run-time: 10 Hours
  • Noise Level: 60 dBA
  • Outlets: 1 – 120V 20A, 120V 30A RV, 1 USB Port
  • Fuel Tank: 1.8 Gallon
  • Size: 26.6×18.9×19.3 In
  • Weight: 90 Pounds
  • Parallel Ready: Yes
  • Warranty: 3-Year
  • User Rating: – 3.50 Out of 5.
  • Expert Score: – 4.30 Out of 5

How does it become a good Portable Inverter Generator?

Provides 2 DC Outputs: There are two 5V USB ports for convenient charging of electronic devices such as cell phones or tablets. While this Generac generator isn’t RV-ready, its L5-30R plug allows for easy RV connection via an L5-30P to TT-30R adapter.

Portability: The Generac GP3500iO has a traditional open-frame design, dimensions: L 19.3 x W 16.9 x H 16.4 inches, which provides support and helps lift it off the ground. The generator is designed for ideal outdoor use and harsh environments. With a dry weight of 74.3 pounds, the GP3500iO lets you put its power where you need it. Additionally, the mobility of the generator is increased by its open-frame design, as it can be easily picked up and moved.

Easy Control Palen: To help you monitor the status and activity of the GP3500iO, your control panel is equipped with a digital data center that gives you insight into lifetime hours of use. In addition to this information, various indicator lights let you know when the generator is ready, the generator is overloaded, and your oil level is low.

Safety: As a safety measure, the device has overload protection (circuit breaker) and automatic shutdown when the oil level is low so that you can use it with peace of mind.

Few More Extra: Besides the classic documentation and a user manual (opens in a new tab) to get you started quickly, the Generac GP3500iO also comes with a few accessories: a tool kit, funnel, and oil included.

Great Price: The Generac GP3500iO is in the middle of the price range compared to other 2500-3500W generators. Therefore, this generator fits very well within the budget provided for this type of product.

Sensitive electronics can be safely connected to AC outlets as the GP3500iO produces a clean sine wave and achieves <3% Total Harmonic Distortion.

Generac GP3500iO Generator Features

Generac GP3500iO Generator Review

Do you travel to places where the electricity supply is a problem? Do you need a generator that you can travel with? A portable and reliable generator is the solution to your problem. We bring you a powerful generator you can carry anywhere because of its compact size and lightweight.

The GP3500iO is ground-breaking because it is portable and has PowerRush Technology. You can take it on a camping trip or to a job site. It is also ready to be plugged into your RV. It has USB outlets, and you can connect two in parallel. Its PowerRush technology delivers 50% more starting capacity, so you can do more with less. It is also 50% quieter, 25% lighter, and supplies clean power. You get many positive attributes, all in one place.

Light and portable

The GP3500iO is light and compact. It weighs around 74.3 pounds and is very portable. You can take it to a cabin in the woods, a camping trip in the mountains, or a remote job site. You can take it anywhere you want. You will not have to worry about both electricity and back problems. It is easy to carry the GP3500iO without fatigue.

You might like this generator even better if you have an RV. You would need extra equipment or a technician to set it up. It connects directly to RV and is easy to set up yourself. It can also power your RV air conditioner up to 15 000 BTU. You won’t have to worry about the summer heat on your road trip. GP3500iO is a traveler’s dream.

Safe and Powerful

The GP3500iO is built with Advanced PowerRush technology. It can deliver over 50% more starting capacity. When the electric motors are started, they can increase electric current on-demand above the rated output. The idea generators can supply the maximum watts in just a few seconds when they are started. The GP3500iO efficiently manages this with 3500 starting watts and 3000 running watts.

Amazing Power Technology

Also, GP3500iO has True Power technology. This technology makes the generator safe to use. You can plug sensitive electronics into this power supply. You will not have to be disappointed about damaging them. The power supplied by this generator is clean. Unlike conventional generators, the power supplied is even. There will not be voltage surges that can use the sensitive circuits in your electronics.

Quiet and Convenient

The GP3500iO is 50% quieter than the average inverter generator. That makes it the right choice for noise-sensitive environments. You can take it out into nature without the guilt of disturbing the peaceful atmosphere. The constant and loud drone of the conventional generator will become a distant memory when you start using this one.

Attractive USB Outlets

The GP3500iO has another useful feature. It has USB outlets so that you can plug your electronics directly into its power supply. You can also easily connect two units of this generator in a parallel arrangement. This will double up the power supply.

Good point about Generac inverter generator 3500

  • High starting capacity
  • Various accessories included
  • Suitable for sensitive electronics
  • Lightweight and Parallel capability
  • Quieter than average inverter generators
  • USB outlets for direct connection of devices

The thing I don’t like about Generac 3500 watt generator

  • No electric start
  • Low fuel consumption
  • A little bigger than I thought
  • Relatively short execution time
  • Adding oil can be complicated
  • It can be connected in parallel but does not come with a parallel kit
Generac GP3500iO Generator weight

It is undoubtedly an excellent feature to maximize the power output through a parallel connection. But it is also an inconvenience to find a compatible parallel kit. You will have to invest in one separately to establish this connection.

Not only that but there are also times when you must change the engine oil. Unlike most inverter generators, this one has separate instructions for an oil change. All of this is done to ensure that the equipment design remains compact.

Generac GP3500iO Generator Review Conclusion

So, if you are looking for an inverter generator to suit your need for reliable power, this is it. Not only are the technological features advanced enough to facilitate their use, but they are also useful. You can now better your experience of generating portable power with this equipment. The power you get is clean and stable. Either way, you can go through the features of this power equipment for yourself before making a final decision.

Generac GP3500iO - 3500 Watt Open Frame Inverter Generator

$839.00  in stock
as of August 27, 2023 6:58 am

Generac GP3500iO Portable Generator Price History

Generac GP3500iO Open Frame RV Ready Inverter Generator, Generac

Price: $839.00
as of August 27, 2023 6:58 am
Wait For A Price Drop

Price History


Current Price $839.00 August 27, 2023
Highest Price $839.00 June 10, 2023
Lowest Price $755.99 April 26, 2023
Since April 26, 2023

Last price changes

$839.00 July 6, 2023
$755.99 June 25, 2023
$839.00 June 10, 2023
$831.96 June 4, 2023
$821.24 May 3, 2023

Generac GP3500iO Portable Generator Review Summary


  1. Generac the best. Just like alot of people said ,put oil and gas in it first pull it starts and unbelievable quit.

  2. krunchnik says:

    Darned Outages. We have been subject to power outages about once a month for hours on end-which pushed me to make power of my own.
    Here in the South in summertime it gets very humid and without air I have a hard time breathing-well no more.
    Fired right up on 2nd pull of the recoil and ran as it should right from the start.
    I installed a wall kit to transfer power indoors without exhaust and rain coming in from an extension cord thru the door.
    This unit will run a 12000BTU air/heat unit and also other electrical items at the same time without barely a complaint.
    If I had to rebuy I definitely would.

  3. SlowBoat2 says:

    The price was good but the shipping is slow, over 2 weeks.

  4. Best overall but still lacks features. After extensive research I chose this for my RV as a dry camp accessory. It is the best value in inverter generators, but lacks one major feature. No wheels or handles, and there are none available as aftermarket add ons. Very cumbersome to manage without them, since it is quite heavy. Otherwise it has everything I wanted, and is reasonable quiet.

  5. Good product. I think its a great generator, however it was damaged upon delivery. The housing cage was bent and the panel also a little bent up. Normally I would have sent it back but needed it ASAP. Overall it runs great but was extremely disappointed with the damage upon delivery.

  6. krunchnik says:

    Primarily Backup. We grew tired of our what seemed like twice monthly power outages-can anyone say aging infrastructure.
    I researched several generators and one constant was a brand name with a good reliability rating and one that was not out of reach of our pocket book.
    I picked a Generac non wheeled generator that is semi portable to me(75 lbs is semi for me).It will sit on a cart in our outdoor shed-where I can run it with the doors open.
    I installed a Reliant Generator through the wall outlet kit that allows running the generator while all our windows and doors can stay shut(hidden Cords).
    3 pulls of the recoil is all it took for initial starting out of the box-and ran very steady.
    Now we can run a portable heat/AC unit if needed along with our other refrigeration and freezer.
    I need something that was large enough to run a couple of appliances at the same time and this generator was of sufficient amperage and voltage.
    We are very happy with our choice and after testing out it kept up quite well.
    Quiet and sufficient power for our needs.
    We’re happy.

  7. Quiet and smooth. Like so many others, we are experiencing fairly frequent outages. Most are quite brief but recently we had one that lasted all day. If it hadn’t been warmer weather we might have had a problem. So.,.. we took the plunge and bought a generator. Since we live on a townhouse and don’t own it, I decided to buy something with enough capacity for the essentials. I also wanted to be able to run as cord to the neighbours to keep them in heat as weIl. It also had to be quiet and reliable. Portability was important.
    I found everything I wanted in this model. I’m presently making a storage box to keep it outside do I don’t have to carry it up from the basement although it’s doable.
    I would recommend this product.
    As a matter of fact, I recommended Generac to my mother and sister in law. They got a larger one since they had the space and wanted something to run more things in the house. Noise level also wasn’t as big a factor for them.

  8. Good generator but.. This is a good little generator, but the only thing I have a problem with is that there is no fuel cut off valve. The off/run/choke switch just turns the generator off and does not run the generator out of fuel. I’m thinking as far as storage. I know the manual talks about fuel stabilizer, but I think a fuel cut off valve would be great. I have owned a few generators in the past and all had a fuel cut off valve to run the generator out of fuel when not in use. I have never had an issue with my other generators, but this is a concern for me.

  9. Louder than expected. Heat shield over the muffler rubs against the muffler and is loud and annoying. I’ll probably take it off and see if I can bend it away so the metals don’t touch each other.
    I bought the generator to camp with so I want to make it a little more quiet. Haven’t gone yet.
    Just filled the oil and put gas in it to test. Ran a heater and skill saw with no issues.

  10. Generac. Extremely fast shipping. I dont have a dB meter, but I personally think its not as quiet as some people stated at less than 50dB. It is a lot quieter than my Coleman 3500. Powers my 5th wheel just fine.

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