RV Generator Guide: Choosing, Sizing and Running One Safely

Generator size is decided by the single largest startup surge in the load, not by adding up running watts. A generator that comfortably covers the running wattage of every appliance running at once can still fail to start a compressor if its surge capacity falls short for even a fraction of a second, because a compressor that cannot reach running speed will trip the generator's overload protection or stall outright rather than draw its way through the surge. Work out the actual surge for your rig's air conditioner and any other motor-driven load with the generator size calculator, then buy to that number rather than the running total.

These are typical published draw ranges for common RV loads. Individual models vary, so confirm against the nameplate on your own unit before buying.

These figures come from adding the running and startup watts above, assuming the second appliance is already running when the air conditioner's compressor kicks on, which is the realistic worst case a generator has to survive.

A conventional generator spins its engine at a fixed speed regardless of load, which is loud at idle and produces raw AC output with more voltage fluctuation than sensitive electronics prefer. An inverter generator produces DC power first and converts it back to clean, stable AC, which is safer for laptops, phone chargers and the circuit boards inside a modern RV converter or inverter. It also throttles the engine speed down under light load instead of running flat out constantly, which is why inverter generators run noticeably quieter and burn less fuel overnight when the only load is a refrigerator and a few lights. The extra cost over a conventional generator of similar wattage is the main trade, and for RV use it is usually worth paying.

NEMA device ratings are published standards, not marketing claims, and they decide whether a generator plugs into your rig directly or needs an adapter.

A soft starter installs at the air conditioner and reduces the compressor's inrush current by ramping it up over a longer window instead of demanding the full surge instantly. That is a real, published reduction in the peak current a generator has to supply for a moment, and it is the reason a 13,500 BTU unit that needs roughly 3,000 startup watts unmodified can start on a generator in the 2,000 watt class once a soft starter is installed. It does not change the compressor's running watts once the unit is up to speed, only the size of the initial spike, so pick the generator's running wattage class against the full appliance list, and rely on the soft starter only for the surge.

Dual fuel models run on gasoline or propane, which matters if your rig already carries propane for the furnace and water heater and you would rather not carry a second fuel. Propane burns cleaner and stores indefinitely compared to gasoline, though a generator typically produces somewhat less output on propane than on gasoline at the same throttle setting, so check the manufacturer's rated output on each fuel before assuming they are identical. Parallel-capable generators can be wired together with a parallel kit to combine two smaller units into one larger effective source, which is a way to grow capacity later without replacing a generator you already own, though the kit and the extra unit both add cost and weight to carry and store.

Most campgrounds post their own generator policy rather than following one nationwide standard, and many restrict or fully prohibit generator use during set overnight hours, so check the specific park's rules before arrival rather than assuming your generator's decibel rating alone makes it acceptable. Point the exhaust away from neighboring sites rather than toward a shared common area or an adjacent rig's windows, since exhaust direction matters as much as raw sound level to the people camping nearby. Store spare fuel in an approved container, away from the generator while it runs and away from any open flame or the rig's own propane appliances, and let a hot generator cool before refueling it.

Fuel consumption depends on load, not just tank size, and it is not a figure this guide can give a single number for, because it varies by generator model and by how heavily it is loaded at any given moment. Manufacturers publish a runtime chart at a stated partial load, commonly a quarter and a half load, on the generator's own spec sheet, and that published figure, checked against your actual expected load, is the honest way to estimate an overnight fuel budget rather than a rule of thumb copied from a different model or size class.

Exhaust needs a clear path away from the RV, from neighboring rigs, and from any door or window that might be opened during operation, since exhaust that pools near an entry point defeats the purpose of running the generator outside at all. Keep the generator off wet grass or standing water, level, and far enough from the rig's own windows and vents that exhaust cannot drift back in through them as wind shifts direction over the course of a run. A canopy or exhaust extension made for the specific generator model helps in rain, but never as a substitute for placing the unit somewhere the exhaust genuinely has room to disperse.

Work out the largest single startup surge in your load first, usually the rooftop air conditioner, using the generator size calculator. Pick a generator wattage class that covers that surge, or plan on a soft starter if you are buying a smaller unit deliberately. Confirm the outlet: a TT-30R for a 30A rig with no adapter, or a 14-50 outlet or a dogbone adapter arrangement for a 50A rig. Decide on fuel type based on what you already carry. Add a soft starter if the surge and generator size do not otherwise match. Install a working CO alarm inside the rig and set placement and fuel storage rules for the campsite before the first time the generator actually runs.

Buy the wattage class that covers your startup surge, not your running watts, and add a soft starter only if a smaller generator is the actual goal. A CO sensor and shutoff is worth paying for regardless of generator size.