Generator for RV Air Conditioner: What Size Actually Starts It (2026)
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How we evaluated: WildJoule has not bench-tested any generator or air conditioner here. Wattage figures come from Honda’s published generator wattage estimation guide; generator specs come from Honda, Yamaha and Champion product pages; soft-starter figures are Micro-Air’s own claims as reported by RV PRO and retailer listings. Checked October 11, 2026.
Sizing a generator for RV air conditioner use comes down to one number most spec sheets bury: starting watts. Honda’s own wattage guide puts a 13,500 BTU rooftop unit at about 1,800 running watts and 2,800 starting watts. A Honda EU2200i is rated 1,800 W running and 2,200 W maximum. On paper, Honda’s own benchmark camping generator can’t reliably start a 13,500 BTU air conditioner by itself, and that one gap explains most of the forum threads about tripped generators at the campsite.
Short answer
For one 13,500 BTU roof unit plus a few small loads, plan on 3,000–4,000 W of generator: a 3,500 W-rated inverter like the Champion 4500, or two 2,200 W inverters run in parallel. A single 2,200 W inverter can work only with a soft starter fitted to the AC and almost nothing else running. Two air conditioners means a 50A rig and a much bigger generator.
Upfront: I don’t own an RV, and I’ve never stood next to a rooftop AC waiting to see if a generator would bog down. I worked this out from Honda’s wattage tables and the makers’ spec sheets. Where I lean on what owners report, I’ll say so. Living where the power drops without warning made me careful about one thing in particular: undersized backup is the kind that fails exactly when you need it.
Generator for RV air conditioner: the wattage table
Honda publishes approximate figures for the three common rooftop sizes. Running watts are what the unit draws once the compressor is turning. Starting watts are the short spike when the compressor kicks on.
| RV air conditioner | Running watts | Starting watts | Realistic generator class |
|---|---|---|---|
| 11,000 BTU | 1,010 W | 1,600 W | 2,200 W inverter, with little else running |
| 13,500 BTU | 1,800 W | 2,800 W | 3,500 W+ rated, or 2 × 2,200 W in parallel |
| 15,000 BTU | 2,000 W | 3,300 W | 3,500–4,000 W+ rated |
Watt figures are Honda’s; the right-hand column is our reading of them. Treat the table as a floor. Your AC is never the only thing running. The converter charging the house batteries, the fridge on electric, a water heater element or a microwave all stack on top. A 30A RV pedestal supplies 3,600 W in total, which is a handy ceiling: a generator in the 3,500–4,000 W range can carry roughly what a 30A campsite would.
Why a 2,200 W inverter struggles with a 13,500 BTU unit
Run the numbers from Honda’s table against Honda’s own generator. The EU2200i makes 1,800 W continuous and 2,200 W maximum. A 13,500 BTU AC wants 1,800 W just to keep running and about 2,800 W for the start. The generator is at 100% of its rating before the fridge or converter draws a single watt, and the starting spike is 600 W past its maximum.
Plenty of owners do report running a 13,500 BTU unit on one 2,200 W inverter. In nearly every case they’ve added a soft starter, turned off the converter and fridge, and kept the generator out of eco mode. Hot weather and altitude make it worse, because a hotter compressor draws more and an engine at elevation makes less power. If you camp in the desert or the mountains, size up.
The Yamaha EF2200iS sits in the same 1,800 W / 2,200 W class, so the same limits apply. Its advantage is the 30A RV outlet on the panel, which saves an adapter. Our Honda EU2200i vs Yamaha EF2200iS comparison covers that trade in detail.
Soft starters: what they change and what they don’t
A soft starter replaces the compressor’s brutal on-switch with a controlled ramp. Micro-Air, which makes the EasyStart most RV owners fit, says its unit produces “consistent reductions of 60 to 75 percent” of locked-rotor amps on most rooftop units, according to RV PRO’s coverage. Micro-Air also says that lets a rooftop AC start on a 2,000 W generator. Those are the maker’s numbers, not ours, and they describe the start only.
That last point matters. A soft starter shrinks the 2,800 W spike, but the 1,800 W running draw of a 13,500 BTU unit stays exactly where it was. On a 1,800 W generator you’ve solved the start and left yourself zero headroom for everything else. It’s a good add-on for a 3,500 W generator, where it lets the fridge and converter keep running while the AC cycles, and a near-requirement if you insist on a single 2,200 W unit.
Three setups that actually work
1. One 3,500 W-rated inverter. The Champion 4,500 W inverter is rated 3,500 W running on gasoline with a TT-30R outlet, so a 13,500 BTU unit plus the fridge and converter fit with room left. The price is weight: Champion lists it at 99.2 lb, which is a two-person lift into a truck bed. Read the Champion 4500W inverter generator review for the model-number confusion between the current 201278 and the older 200988.
2. Two 2,200 W inverters in parallel. Two EU2200i units linked with a parallel kit give up to 4,400 W maximum, and each half weighs under 50 lb. You carry two light boxes instead of one heavy one, and on cool evenings you can run just one. You do need two of the same model, the right kit, and two tanks to fill. Our best generator parallel kits guide covers the compatibility rules.
3. One 2,200 W inverter plus a soft starter. The lightest option and the least forgiving. It works for an 11,000 BTU unit with margin, and for a 13,500 BTU unit only if you’re disciplined about switching everything else off. Fine for a weekend; frustrating for a week in July.
Sizing a generator for RV air conditioner plus everything else
Here’s the method, using a 13,500 BTU roof unit as the example:
- Add up the running watts of everything that can be on at once: AC 1,800 W, plus the converter, the fridge on electric and any small loads. Check each label rather than guessing.
- Find the single biggest starting spike. That’s almost always the AC compressor at about 2,800 W (less with a soft starter).
- Your generator’s running rating must cover the first total. Its starting rating must cover everything else running plus that one spike.
- Leave 10–20% headroom for heat, altitude and the fact that generators sag near their limit.
If the total lands above about 3,600 W, you’re past what a 30A rig can use anyway, and you’re probably looking at a 50A coach with two air conditioners. That’s a different class of generator; the best inverter generator for RV guide sorts the options by plug type.
Could a power station run the AC instead?
For a few hours, a large one can. At 1,800 running watts, a 13,500 BTU unit would empty a 4 kWh power station in a little over two hours of continuous compressor time, before inverter losses. The compressor cycles, so real runtime is longer, but it’s still an evening, not a night. That’s why generators still own this job. Our generator vs power station comparison lays out where each one wins.
Campground and safety basics
National Park Service rules (36 CFR 2.12) bar running a generator in a way that exceeds 60 dB(A) measured at 50 feet, and individual campgrounds add their own quiet hours. Inverter generators are usually the only kind that stay comfortably inside that. Run the generator outside the rig, exhaust pointed away from your door, windows and your neighbours’ awning. Our portable generator carbon monoxide safety guide covers placement and CO alarms; RVs have plenty of gaps for exhaust to get in.
Prefer one generator to a parallel pair? The Honda EU3000iS review looks at the single-unit route: 3,000 W maximum against the 2,800 W Honda lists for a 13,500 BTU start, with the trade-off being 130.7 lb.
Frequently asked questions
What size generator do I need for a 13,500 BTU RV air conditioner?
Honda puts a 13,500 BTU unit at about 1,800 running and 2,800 starting watts. With other loads on, a 3,500 W-rated generator or two 2,200 W inverters in parallel is the comfortable choice.
Will a 2,000 or 2,200 W generator run an RV AC?
An 11,000 BTU unit, usually yes. A 13,500 BTU unit only with a soft starter and almost nothing else running, and even then hot days and altitude can tip it over.
Does a soft starter let me use a smaller generator?
It shrinks the starting spike (Micro-Air claims 60–75% less locked-rotor current) but not the running draw. You still need a generator whose running rating covers the AC plus your other loads.
Can I run two RV air conditioners on one generator?
Two units means 3,600 W or more of running load before anything else, which is beyond a 30A rig. That’s 50A territory and usually a 7,000 W+ generator.
Further reading: Honda’s generator wattage estimation guide, and our RV power guide for the rest of the rig.
Last updated: October 11, 2026. This generator for RV air conditioner guide uses Honda’s published wattage estimates; your unit’s nameplate is the final word. We do not display live prices.