When your old RV Onan quits—maybe right in the middle of your trip—this direct replacement brings back quiet, reliable power for your RV AC, fridge, and more, so you can keep exploring with all the comforts of home, no hookups required.
If your old generator finally gave out, this Onan QG 2500i fits in the same spot as your original. You'll still need to hook up the fuel line, electrical, and exhaust, but the major work is already done for you. Enjoy the comforts you count on—morning coffee, fully charged devices, and lights on at any hour. Plus, it has enough power to run one 13,500 BTU high efficiency air conditioner, so you can beat the summer heat and stay comfortable wherever you park.
After a long drive or when the weather turns wet and rainy, nobody wants to wrestle with a bulky generator. With one-touch start and remote switching capability, powering up is always simple, rain or shine. All you have to do is press the power button and relax. And the built-in shutoffs handle low oil, overloads, and engine quirks automatically, so you can settle in for the night with your fridge cold, your CPAP on, and no worries about unexpected shutdowns.
The built-in inverter delivers clean, stable electricity—perfect for laptops, tablets, and other sensitive electronics. No more worries about power surges or fried circuits. Your devices stay safe, your lights don't flicker, and you get reliable AC power for today's gear.
This generator uses sound-dampening technology and a special muffler to help keep things peaceful. You won't have to raise your voice for campfire stories, cut conversations short, or lose sleep to engine noise. It also meets National Park Service noise guidelines, so you can experience brilliant fall foliage in the Great Smoky Mountains or visit the steaming geysers at Yellowstone without worry.
From routine oil changes to swapping out the air filter, service is straightforward. No need to be a mechanic—just basic tools and a few minutes are all it takes to keep things running strong for years to come. And with built-in self-diagnostic capability, troubleshooting issues is faster and easier so you can spend less time on maintenance.
California residents: click here
Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.
Hi everyone. Steve here with etrailer.com. Today we're looking at our Cummins Onan QG 2,500i Onboard RV Generator with inverter. 2,500 watts of power running on propane and it's carb compliant. Folks, if you've had yours for years and years and it finally either stopped working or you just wanna upgrade to something newer, this can be an option for you. You wanna match up the dimensions on this guy and you wanna make sure that it's something that fits the wattage output that you require in your RV or camper.
Now, if this is not your cup of tea, you don't want to do the install, you can reach out to etrailer.com on our homepage and on our Dealer Locator tool, we can help assist you with finding someone in your area that can help get this installed for you. I do wanna zoom in here so we can take a look at everything. So to get this front access panel off, it's really simple. It says open and close on here. You just simply turn the direction for open, pull it down and out.
You got some soundproofing in here, and now you can access your oil, air filter, your on/off switch, the breaker, and pretty much everything in here that you need for maintenance. Now there was four bolts that held this on top. I went ahead and removed them before our time together here. That way I can take this off and give you a better look at the inside. So starting from the front here, you can see again all that general maintenance stuff, oil fill, all those kind of good things.
Let's go ahead and take a look from the top down real quick. And again, just to give you a different view of everything. You have your muffler right here. Now this is an extra quiet muffler. It is also a enclosed muffler as far as when you have everything installed.
So it's gonna be quieter. It does meet all National Park service requirements of that max 60 decibels at 50 feet. And it's a USDA Spark Arrester Muffler Certified. So that means it's safe for national forest and campgrounds. So no mods needed whenever you're ready to go. Coming back from the front here, I'm gonna go ahead and do a little spin here. So right here is gonna be your main propane hookup and they just got that cap on there for protection for shipping. Your main power wires are coming out of here. You do have two harnesses. These should match up exactly the same with the harness that's already in your RV, camper, trailer, whatnot. Come back here to the back, you got your main battery hookup, you have your ground and positive. And then again, there's that quiet muffler and they do give you an exhaust tube extension here and gasket and bracket. And all of that is gonna go behind this little gray piece here, silver, that pops out. And this will go through there and connect in there with all those pieces to then connect to your tailpipe or your exhaust for this generator. Now you can be rest assured that this is gonna be great and safe for you. It does have built-in shutoffs for low oil, overloads and engine issues so you can relax whenever you park and not have to worry about it getting overloaded. And also from routine oil changes to swapping out that air filter, it is really simple. So the air filter itself is just a couple tabs here that you would pop out. And then you can access the main air filter in there for maintenance. The oil drain is gonna be underneath the bottom. And then of course you have your main oil fill down here. And then of course your on/off switch that we mentioned already. So not a lot of stuff to do as far as maintenance. You don't have to be a mechanic. Just have some basic tools, a couple minutes and you should be able to service it yourself. Now, we talked about this having an inverter. Basically the built-in inverter is gonna deliver you clean, stable electricity. So it's gonna be safe and great for laptops, tablets, and other sensitive electronics that you might be running. You don't have to worry about power surges and fried circuits. Your devices are gonna stay safe and your lights aren't going to flicker and those kind of things either. So it really is a great upgrade if you don't have that inverter on your current one. Well folks, that's gonna wrap it for our quick look together. I'm Steven, thanks for watching.
This item is sold as a direct replacement for an old Onan of the same output, but it was far from that for4 me. The product description says that it is a direct drop in with no adapters needed. One is supposed to only hook up the fuel line and the electrics. My experience was that I had to completely rework the mounting surface of the generator compartment of my Bigfoot truck camper. I replaced a 20 year old Onan KVD model. The engine and the generator of the old model are opposite of the new unit which meant cutting out new air exhaust openings and patching in the old cutouts. New holes for mounting the generator were needed to be drilled. The cover for the generator enclosure had to be removed and replaced with one that had the opening directly opposite the air intake of the generator per Cummings instructions. All in all, I’m pleased with the new unit. However, it was a much bigger challenge than I was expecting
Sam C- Product Expert (Solar & Electrical Systems)
If you're running lithium batteries in your RV, whether you're full-time, off-grid, or just solar-prepped—an Onan inverter generator like the CM25ZR, CM42ZR, or CM52ZR is an excellent choice for reliable backup power.
These models produce pure sine wave AC output, which is essential for charging lithium batteries safely, especially if you’re using a smart battery management system (BMS). Unlike traditional generators that can deliver "rough" or fluctuating power, inverter generators deliver the clean, stable voltage that lithium chargers and inverters require. This reduces the risk of fault codes, overheating, or improper charging.
Another benefit is how well these generators integrate with modern inverter/charger systems. A lot of lithium setups use gear that expects high-quality power—if you feed it unstable current, the system might reject it or shut down charging altogether. The CM25ZR and other inverter models solve that problem by producing grid-like power that your system can accept with no issue.
The engine speed ramps up or down based on demand, which is perfect when you’re just topping off your batteries after a few cloudy days or running overnight loads like a fridge and CPAP. Many lithium users also install auto-generator start (AGS), and these models pair well with that kind of automation.
If your rig is lithium-equipped and you want a generator that won’t fight your charging setup or worse, damage it—these Onan inverter models are designed with that compatibility in mind.
Kate F- Product Enthusiast at etrailer.com
I’ve helped quite a few customers lately who work remotely and need to charge laptops, monitors, and camera gear while they’re traveling. Whether they’re full-timing or just working from the road, one thing they all have in common is needing clean, stable power and that’s where an inverter generator makes all the difference.
The Onan inverter models, like the ones under part numbers CM25ZR, CM42ZR, or CM52ZR, are built to produce pure sine wave power, which is just a fancy way of saying they give you the same safe, consistent electricity you’d get at home. That means your laptop charger isn’t going to buzz or overheat, and you’re not putting wear and tear on your devices every time you plug in.
I always tell people, if you’re relying on your tech for work, Zoom calls, editing, charging your batteries, this is one area where you don’t want to compromise. Plus, inverter generators are quieter and more fuel-efficient, so you’re not stuck listening to a loud rumble all day while you’re trying to focus or take a call.
If your RV is your mobile office (even part-time), having an inverter generator isn’t just a luxury, it’s a smart move that protects your gear and makes work on the road way less stressful.
Chris R- Product Enthusiast at etrailer.com
Here’s the deal: if you’ve got a small trailer or camper with a generator bay that’s been sitting empty, the Onan CM25ZR is a clean, easy solution—especially if you're running LP (propane) already. No gas cans. No fumes. No “I forgot to fill it” regret at 9 p.m.
This generator puts out pure sine wave power, which means your electronics won’t hate you for plugging in your laptop, router, or Starlink while off-grid. The inverter setup keeps things quiet and efficient, so you're not waking up your neighbors or yourself when it kicks on.
At 2,500 watts, it’s not trying to power a rock concert. But it will handle your fridge, lights, and your coffee setup because we all have priorities. Great for R-Pods, Micro Minnies, and other rigs in the sub-25’ range.
Jesse M- Product Enthusiast at etrailer.com (install and training team)
Install-wise, this unit is way lighter than a lot of the bigger onboard generators. If your trailer is generator prepped, it should drop right into the factory bay with minimal fuss. As long as you're comfortable working with propane and basic electrical, it's a doable DIY project.
For weekend campers, solo travelers, or couples off-grid camping with lighter trailers, this unit is a smart, efficient choice. It’s quiet, dependable, and sized just right for trailers that can’t accommodate bulkier units.
Heather A- Product Enthusiast at etrailer.com
One of the big advantages of the Onan CM25ZR is how compact and lightweight it is compared to traditional onboard generators. If you’ve got a smaller travel trailer like the Winnebago Micro Minnie FLX, this is a big deal.
This generator is much easier to install in tight generator bays, and it won’t weigh your trailer down, huge if you're already close to your cargo limit or towing with a mid-size SUV or half-ton truck. It’s propane-powered, so it taps into the LP you already carry, and there’s no need to lug around separate gas cans.
Info for this part was:
At etrailer.com we provide the best information available about the products we sell. We take the quality of our information seriously so that you can get the right part the first time. Let us know if anything is missing or if you have any questions.
Thank you! Your comment has been submitted successfully. You should be able to view your question/comment here within a few days.
Error submitting comment. Please try again momentarily.