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If your old generator's stopped working or you want cleaner, quieter power, the QG 2500i is a dependable upgrade. It runs a high efficiency 13,500 BTU A/C plus your essentials, so you can stay cool wherever you camp.
If your old generator has worn out or you're stepping up to cleaner, more efficient power, this QG 2500i propane onboard generator delivers dependable performance for the essentials that make RV or van life more comfortable. It provides enough output to run a 13,500 BTU high-efficiency air conditioner along with your fridge, outlets, and small appliances, so you can enjoy morning coffee, charged devices, and cool air wherever you park.
If you're replacing a previous Onan QG 2500i, the overall layout is designed to be very similar. Intake, exhaust, and drain locations generally align with earlier models, so major bay modifications usually aren't required. You'll still need to reconnect the propane line, electrical wiring, and exhaust components, and minor adjustments may be necessary depending on your RV's setup. As with most onboard generators, working with an experienced installer can help ensure everything is set up correctly the first time. You can use etrailer's installer locator to find a qualified shop near you and get help with install.
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. The consistent voltage helps protect sensitive electronics from surges and fluctuations so there are no flickering lights or unexpected voltage dips. If your rig runs an inverter/charger and lithium battery bank, this stable AC output also supports charging without nuisance faults or power rejection. 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 replacing the air filter, regular service is straightforward. You don't need to be a mechanic - basic tools and standard maintenance intervals are usually all it takes to keep things running reliably for years to come. And with built-in self-diagnostic capability, troubleshooting issues is quicker and easier so you can spend less time tracking down problems and more time enjoying your RV.
For many RV owners, an onboard generator quickly becomes something they rely on every trip. It allows you to manage heat, power appliances, and stay comfortable without planning around hookups. That kind of reliability matters more the longer you own your RV. If you're replacing an older unit, upgrading to more power, or adding an onboard generator for the first time, the QG 2500i supports travel that's less restricted by weather, location, or campground availability. It's an upgrade that continues to pay off over years of use.
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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.
Haven’t installed yet, heard nothing but good news
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.
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.
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.
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Condition: Surface Scratches
Notes: The cover has paint chips. Otherwise new and unused.
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Kate F.
2/25/2026
What kind of camper will you be installing it in Timothy?