RV Generators: Portable vs Built-In, and When You Need One

Emily and I resisted buying a generator for two full years of RV life. We had solar panels, we had lithium batteries, and we had a deep-seated belief that generators were loud, smelly, and unnecessary for enlightened RVers who had embraced renewable energy. Then we spent a week in the Pacific Northwest in October. Four straight days of rain and thick cloud cover. Our solar panels produced approximately nothing. Our batteries drained to 20 percent by day two. We could not run the heater, the coffee maker, or charge our laptops. We sat in a cold, dark RV and reconsidered our life choices.

The next week we bought a portable generator, and it has been one of our most-used pieces of equipment ever since. Not because we run it every day, we still rely primarily on our solar panel setup, but because when you need a generator, nothing else will do. Here is everything we have learned about choosing, using, and maintaining an RV generator.

Do You Actually Need a Generator?

Before we get into types and models, let us honestly assess whether you need one at all. Many RVers do not. If you primarily stay at campgrounds with electrical hookups, a generator sits in your storage bay collecting dust. If you have a solid solar and battery setup and camp in sunny climates, you may never need supplemental power.

You probably need a generator if you regularly boondock in cloudy or shaded locations, if you need to run air conditioning off-grid (solar alone cannot handle most rooftop AC units), if you work remotely and cannot afford power gaps, or if you travel in winter when solar production drops significantly. Our boondocking beginners guide covers how to evaluate your off-grid power needs in detail.

Generator vs. Larger Battery Bank

Some RVers skip the generator entirely and invest in a massive lithium battery bank instead. A 400-amp-hour lithium setup (about $3,000 to $4,000 for the batteries alone) stores enough energy for two to three days of moderate use without any charging source. Pair that with 600 to 800 watts of solar and you have a system that handles most situations.

The math favors batteries plus solar for fair-weather campers. But a generator costs $500 to $2,000 and provides virtually unlimited power as long as you have fuel. For the price of upgrading from 200ah to 400ah of lithium, you can buy a excellent portable generator that handles every edge case. We chose to keep a moderate battery bank plus a generator as backup, and it has been the right decision for us. For more on the battery side, our lithium vs lead-acid battery guide breaks down the tradeoffs.

Portable Generators vs. Built-In (Onboard) Generators

Portable Generators

Portable generators are standalone units that sit outside your RV. You connect them to your RV with an extension cord or a dedicated shore power inlet cable. Modern inverter generators are remarkably quiet, fuel-efficient, and produce clean power that is safe for sensitive electronics.

Advantages of portable generators: lower cost ($500 to $2,000 for quality inverter models), can be used for other purposes (powering tools, home backup), easy to maintain and repair, can be stored separately from the RV, and replaceable without any RV modifications. You also have the option of carrying it into the bed of your truck while driving and setting it up only when needed.

Disadvantages: requires manual setup and fueling, takes up storage space, must be monitored during operation, and you need to manage the extension cord. There is also a theft risk since portable generators sitting outside an RV are unfortunately attractive targets at campgrounds.

Built-In (Onboard) Generators

Built-in generators mount permanently to the RV frame, usually in a dedicated compartment. They connect directly to the RV electrical system and can be started from a switch inside the RV. Many Class A motorhomes and larger fifth wheels come with built-in Onan or Cummins generators from the factory.

Advantages of built-in generators: convenience of push-button start from inside, no setup or cords required, draws fuel directly from the RV fuel tank (on motorhomes) or a dedicated propane or diesel tank, and they are secured against theft. For motorhome owners, a built-in generator is part of the integrated system, similar to how the propane system ties into multiple appliances.

Disadvantages: significantly higher cost ($3,000 to $8,000 installed), more complex maintenance, cannot be used separately from the RV, and repairs often require a specialist. If a built-in generator fails, you are stuck until it is fixed, you cannot just swap it for a new one at a hardware store.

Sizing Your Generator: How Many Watts Do You Need?

Generator size is measured in watts. You need enough wattage to run everything you want to power simultaneously, plus a margin for startup surges. Electric motors (like your AC compressor) draw 2 to 3 times their running wattage when they first start. This startup surge lasts only a second or two, but your generator must handle it.

Calculating Your Needs

List everything you want to run at the same time and add up the wattage:

RV air conditioner (13,500 BTU): 1,300 to 1,800 running watts, 2,800 to 3,500 startup watts. This is the biggest single load for most RVers and the main reason you need a generator larger than 2,000 watts.

Microwave: 800 to 1,200 watts running. No significant startup surge.

Coffee maker: 600 to 900 watts running. High-draw for something so small.

Residential refrigerator: 100 to 200 watts running, 400 to 600 watts startup.

Laptop charger: 45 to 90 watts each. Negligible.

Phone charger: 5 to 20 watts. Negligible.

LED lights: 10 to 50 watts total. Negligible.

Battery charger/converter: 200 to 600 watts depending on charge rate.

Recommended Generator Sizes

2,000 to 2,200 watts: Handles everything except AC. Good for charging batteries, running a microwave, making coffee, and powering electronics. This is the sweet spot for camper vans and small trailers that do not need generator-powered AC. Models like the Honda EU2200i and Yamaha EF2200iS are the gold standard in this class.

3,000 to 3,500 watts: Handles one rooftop AC unit plus basic loads. This is the most popular size for travel trailer owners. You can run AC and a few other things, but not AC plus a microwave plus a coffee maker simultaneously. You need to manage loads by turning off the coffee maker before starting the microwave.

4,000+ watts: Handles one AC unit plus all other loads comfortably, or two AC units with load management. Necessary for large rigs with high power demands. These generators are heavier (80 to 120 pounds) and louder, so the tradeoff is less portability.

Fuel Types: Gas, Propane, or Dual-Fuel

Gasoline: Most portable generators run on regular gasoline. Gas is available everywhere, generators are most efficient on gas, and the technology is mature. The downside is that gasoline goes stale in 30 to 60 days without a fuel stabilizer, it is messy and smelly to store, and you need to carry extra fuel safely (which means approved gas cans strapped down in a ventilated location, never inside the RV).

Propane: Some generators run on propane, and many RVers already carry propane for cooking and heating. Propane does not go stale, burns cleaner than gasoline, and is easy to store in standard tanks. The downside is slightly lower power output (about 10 percent less than gas) and less availability for portable generator models.

Dual-fuel: Dual-fuel generators run on either gasoline or propane, giving you maximum flexibility. We run a dual-fuel model and primarily use propane because we always have it on hand. When propane runs low, we switch to gas. Dual-fuel models cost $50 to $100 more than gas-only equivalents, and the flexibility is worth every penny.

Generator Etiquette and Campground Rules

Generators are controversial at campgrounds because noise affects everyone nearby. Following generator etiquette is not optional, it is what keeps everyone civil and prevents campground bans on generators entirely.

Respect quiet hours. Most campgrounds enforce quiet hours from 10 PM to 7 or 8 AM. Running a generator during quiet hours is the fastest way to make enemies and get yourself asked to leave. Some campgrounds prohibit generators entirely, and more are heading that direction. Check the rules before you assume you can run yours.

Keep it as far from neighbors as possible. Set your portable generator on the side of your RV farthest from adjacent campsites. Even a quiet inverter generator produces 50 to 60 decibels at 25 feet, which is the level of a normal conversation, noticeable and potentially annoying to someone relaxing at their campsite.

Limit runtime. Run your generator for specific tasks (charge batteries, run AC during the hottest part of the day) rather than running it all day. Two hours of targeted generator use is enough to charge a battery bank that carries you through the rest of the day, which is how we integrate our generator with our overall mobile power and connectivity setup.

When boondocking, be aware of sound carry. In the desert or mountains, sound travels much farther than you expect. Even at a dispersed campsite with no official rules, a generator running all afternoon will be audible to campers a quarter mile away.

Generator Maintenance

A generator that starts reliably when you need it requires basic maintenance that most people neglect. We have helped fellow campers troubleshoot dead generators dozens of times, and the cause is almost always the same: stale fuel and a carburetor gummed up from sitting unused.

Monthly (During Use)

Check oil level before every use. Change oil every 50 to 100 hours of operation or at least once per season. Clean or replace the air filter every 50 hours. Inspect the spark plug every 100 hours and replace annually. Check all fuel connections for leaks.

Seasonal Storage

This is where most generator problems originate. If you are storing your generator for more than 30 days, either run the fuel tank and carburetor completely dry, or add fuel stabilizer to a full tank and run the generator for 10 minutes to circulate the stabilizer through the system. Stale gasoline creates varnish that clogs the tiny jets in the carburetor. A $15 bottle of fuel stabilizer prevents a $150 carburetor cleaning. The same kind of seasonal preparation mindset applies to all your RV systems, as we cover in our winterization guide.

Annual

Replace the spark plug. Change the oil (even if hours are low). Replace the air filter. Inspect the fuel lines and connections. Test the output with a multimeter to verify clean power. Load test by running the generator at full rated capacity for 30 minutes and checking for overheating, unusual noise, or voltage fluctuations.

Safety: Carbon Monoxide Is Not Negotiable

Every year, campers die from carbon monoxide poisoning caused by generators running too close to their RV. Carbon monoxide is odorless and colorless. You will not know you are being poisoned until you lose consciousness, and by then it may be too late.

Never run a generator inside any enclosed space. This includes inside your RV, in a closed garage, under an awning with restricted airflow, or anywhere the exhaust can accumulate.

Position the exhaust facing away from your RV and all nearby RVs and tents. Wind can push exhaust back toward your rig, so check wind direction before starting the generator.

Install carbon monoxide detectors inside your RV. Battery-operated detectors cost $20 to $30 and save lives. We have two: one near the bedroom and one in the main living area. Test them monthly and replace batteries annually. This is safety equipment in the same category as the smoke and propane detectors we discuss in our propane safety guide.

Maintain at least 20 feet of distance between the generator exhaust and any opening on your RV, windows, doors, roof vents, AC intake.

Our Generator Setup

For reference, here is what Emily and I use and how it fits into our overall power system. We carry a dual-fuel 3,000-watt inverter generator as our primary backup power source. On sunny days, our 600-watt solar array and 300ah lithium battery bank handle everything. On cloudy days or when we need AC, we run the generator for two to three hours to charge the batteries and cool down the RV, then shut it down and coast on battery power.

Total fuel consumption averages about 2 gallons of propane per generator day, which comes out to less than $8 per day in propane. Compared to the $40 to $60 per night we used to spend on campground hookups, the economics are obvious. The generator paid for itself within three months of boondocking.

If you are thinking about your overall off-grid power strategy, the generator is just one piece. Combine it with solar, a good battery bank, and smart power management habits and you have a system that handles anything the road throws at you. Check our essential RV apps guide for tools that help you find free camping spots where your generator and solar setup let you stay as long as you want.

Stay powered up, Mike & Emily