What Size Generator Do You Need to Run an RV Air Conditioner?

Running an RV air conditioner is the most common reason campers buy a generator, and it is also where many buyers undersize. The AC’s running watts may fit easily within a small inverter’s rating, but the compressor’s starting surge can trip it instantly. This guide explains what size generator you need for one or two RV air conditioners, how soft starters change the equation, and how to plan fuel for boondocking in the heat.

Generator size for RV air conditioners

Soft starters: the small-generator enabler

A soft start module installed on the AC compressor reduces starting inrush by about 50–70%. With one installed, many 13,500 BTU units start reliably on a 2,200–2,500W inverter, and even some 15,000 BTU units run on a 3,000W-class unit. Installation typically takes under an hour. Check your AC’s warranty terms before modifying it.

Choosing the right generator type

Inverter generators are the standard for RV use because they are quieter — often 52–60 dBA at 23 feet at typical loads — and comply with campground noise rules. They also deliver clean power for RV electronics, converters and control boards. For 50A RVs running two ACs, look for a 7,000–9,000W inverter with a 14-50R outlet, or two parallel-capable units.

Fuel and runtime planning

RV AC use is often sustained for many hours in hot weather, so fuel planning matters.

Dual fuel generators running on propane use roughly 1.5–2 lb of propane per hour at moderate loads, so many RVers carry extra cylinders or tap the RV’s onboard propane tank with an appropriate connection.

Altitude and heat derating

Generators lose roughly 3–4% of output per 1,000 feet of elevation. At 5,000 feet, a 3,000W generator may deliver closer to 2,500W, which can make the difference between an AC starting or not. High ambient temperatures also reduce output. If you camp in mountains or deserts, add a size or rely on a soft starter.

Connection tips

• 30A RVs connect to a TT-30R outlet; use a quality adapter if the generator only has an L5-30 or L14-30.
• 50A RVs need a 14-50R outlet or a parallel kit with a 50A connection.
• Use a surge protector or EMS between the generator and RV to guard against voltage issues.
• Turn off the RV’s electric water heater and battery charging while starting the AC if capacity is tight.

Campground rules and generator etiquette

Many public campgrounds limit generator use to specific hours, often 8 a.m. to 8 p.m. with a midday quiet period, and some cap noise at around 60 dBA at 50 feet. A quiet inverter meets these limits comfortably; open-frame conventional generators often do not. Point the exhaust away from neighboring sites, keep the generator on level ground, and use a chain lock to prevent theft. If you need AC during quiet hours, a lithium battery bank of 5 kWh or more, charged by the generator during allowed hours, can run a soft-started rooftop unit for a few hours in the evening.

FAQ

Can a 2,000W generator run an RV air conditioner?

Often yes for 11,000–13,500 BTU units with a soft starter installed. Without a soft starter, most RV ACs need 3,000W or more.

What size generator do I need for a 50A RV with two ACs?

Plan on 7,000–9,000W, or two parallel inverters totaling at least 6,000W with soft starters on both ACs.

Bottom line

For one 13,500 BTU RV AC, a 3,000–3,500W inverter is the reliable choice, or 2,200–2,500W with a soft starter. Two ACs on a 50A RV need roughly 7,000–9,000W. Choose an inverter for quiet, clean power, and add margin for altitude and heat.