Will a 2,000 watt generator run a 13,500 BTU RV air conditioner?

It's the question every RV owner with a small generator asks on the first hot day. The honest answer is "not on its own, but often yes with one upgrade."

The numbers

	Running watts	Starting watts
13,500 BTU RV AC (Champion chart)	1,500–2,000	2,800–3,500
13,500 BTU RV AC (Honda chart)	1,800	2,800
Our calculator	1,500	3,000
Typical "2,000 W" inverter generator	about 1,600 (varies)	2,000

The problem is the start. For a second or two, the AC's compressor asks for about 3,000 watts. A 2,000 W generator can't give that. Its overload protection trips, and the AC never gets going.

Even once running, the AC uses 1,500–2,000 W. That's close to what a small generator can give all day. On a hot afternoon, the AC works harder and draws more.

So the answer is:

• Stock AC, no soft start: no. It won't reliably start.
• With a soft start kit: often yes, with little else running.
• Two 2,000 W generators linked with a parallel kit: yes. If each is rated 1,600 running and 2,000 starting, together they give about 3,200 running and 4,000 starting watts.
• One 3,000 W+ generator: yes. See what a 3,500 watt generator can run.

The tool above is set to a 2,000 W generator (1,600 running, 2,000 starting) and a 13,500 BTU AC with no soft start. Switch "soft start" to yes and watch the verdict change. Put in your generator's real ratings for a better answer.

What about a 2,200 watt generator?

A little more headroom helps, but not enough to start a stock 13,500 BTU AC. 2,200 starting watts is still well under the 2,800–3,500 W the AC needs. With a soft start, the extra 200 W or so gives you a bit more room for the fridge or lights.

What a soft start kit does

A soft start is a small electronic box wired into the AC. Instead of slamming the compressor on at full power, it eases it up to speed over a moment. That cuts the start-up surge.

The maker of one popular kit says it can "reduce your current by up to 75%" at start-up. Its product page carries customer reports of a 13,500 BTU AC starting on a single 2,000 W class inverter, including one where the AC first tripped the generator and then started fine once the kit was in. Those are the maker's own customer reports, not independent tests. Results depend on your AC, the heat and the altitude.

You can fit one yourself or have an RV shop do it. Follow the kit's instructions, and turn off shore power and the generator before opening the AC's cover.

If you add a soft start, keep the rest light

A soft start fixes the start. It doesn't shrink the running load. With the AC running at 1,500–2,000 W, a 2,000 W generator has very little to spare. So:

• Turn off the microwave, electric water heater and coffee maker while the AC runs.
• Set the fridge and water heater to propane if they have that option.
• Turn eco or idle mode off if the generator struggles when the compressor kicks on.
• Pre-cool early in the day, before it gets hottest.

Altitude and heat make it harder

Generators lose power as you climb. A Westinghouse manual puts it at about 3.5% for every 1,000 feet, and about 1% for every 10°F of heat. At 5,000 feet, a 2,000 W generator acts more like 1,650 W. In the mountains, even a soft-started AC may be too much for one small unit.

Two small generators vs one bigger one

Two 2,000 W inverters with a parallel kit

• Easy to carry, one at a time.
• Use one on mild days to save fuel.
• A 30 A parallel kit is rated for up to 3,600 W, the limit of a 30 amp RV.

One 3,000–4,500 W generator

• One engine to fuel and maintain.
• Plenty for one AC plus the basics.
• Heavier to lift in and out of a truck.

Either works. For what size fits your whole trailer, see what size generator for a 30 amp RV.

Check your own AC and generator

• The AC's label is on the roof unit or inside the ceiling shroud. Look for BTU, running amps and "LRA" (locked rotor amps). Running amps × 120 = running watts.
• The generator's spec sheet lists running (rated) and starting (peak) watts. Use both in the tool above.
• A 15,000 BTU AC needs more: about 2,000–2,500 running and 3,500–4,500 starting watts in Champion's chart. That's more than a single 2,000 W generator can run all day. One of the soft-start maker's customer reports claims a 15,000 BTU AC on one small unit, but treat that as a long shot.

Safety: Run it outdoors only, 20+ feet from the house, away from windows and doors. At camp, keep it 20+ feet from your RV and your neighbors', with the exhaust pointed away. Read our carbon monoxide guide.