Understanding the Power Requirements
Generator sizing for RV use centers almost entirely on the air conditioner. Everything else — microwave, TV, lights, phone chargers — adds up to a fraction of the AC's power demand. A standard 13,500 BTU rooftop RV AC draws 1,500–1,700 watts running and surges to 3,000–4,500 watts at startup. Dual AC units (common on Class A motorhomes) nearly double these requirements.
RV power loads: 13,500 BTU AC = 1,500–1,700W running / 3,000–4,500W surge. 15,000 BTU AC = 1,800–2,000W running / 3,600–5,400W surge. Microwave = 700–1,000W. Electric water heater = 1,300W. Slide-out motors = 400–600W per slide. TV = 80–150W. Lights = 50–100W total (LED). A typical Class C or travel trailer with one AC runs 2,000–2,500W continuously.
Choosing the Right Generator Size
For most travel trailers and Class C/B motorhomes with a single AC: a 3,500-watt generator minimum, 4,000 watts recommended. With a soft-start kit on the AC, a 3,000-watt inverter generator becomes possible. Class A motorhomes with dual AC units: 7,500–10,000 watts. Built-in RV generators (Onan, Cummins) are typically 4,000W for smaller RVs and 6,500–12,500W for Class A.
This appliance surges to 5.5 kW (2.3× running watts) at startup. Your generator's starting watts — not rated watts — must exceed this. Always verify the generator's peak/surge rating before purchasing.
Wattage Summary
| Specification | Value |
|---|---|
| Running Watts | 2.4 kW |
| Surge Watts | 5.5 kW |
| Minimum Generator | 3.5 kW |
| Recommended Generator | 4 kW |
Buying Tips
A MicroAir EasyStart soft-start kit ($200–$250) lets most 13,500 BTU RV ACs run on a 2,000-watt inverter generator — a game-changer for campground quiet hours.
Honda EU3000iS (2,800W) and Champion 3500W are popular choices for travel trailers with soft-start AC.
Check your RV's shore power requirement (30A or 50A) — this doesn't directly dictate generator size but gives you a sense of total capacity designed for.
Onan-brand RV generators are the OEM standard but are expensive — aftermarket Champion, Generac, and Westinghouse units offer comparable performance.
What Else Can Run With It?
Common appliances paired with this load. Combined running load: 3.4 kW. Recommended generator for this combo: 4 kW.
| Appliance | Running Watts |
|---|---|
| What Size Generator for an RV ← this page | 2400W |
| RV Microwave | 700W |
| TV | 120W |
| Lights (LED) | 80W |
| Phone/Laptop | 115W |
| Combined Running Total | 3.4 kW |
* Recommended generator for this combination: 4 kW (includes 20% safety margin and surge headroom)