Power Station for an Air Conditioner
Air conditioners are decided by startup surge, not steady watts. A 13.5K BTU RV rooftop AC draws about 1,500 W steady but peaks near 3,000 W at compressor start — that surge sets the inverter size, and the steady draw sets the battery size.
Bottom line
Startup surge decides the inverter (max(1,500 × 1.25, 3,000) = 3,000 W); steady draw decides the battery (~1,500 W per running hour for the RV unit).
AC power table
| Type | Running | Startup surge | Source |
|---|---|---|---|
| RV rooftop AC — 13.5K BTU class (Dometic) | ≈ 1,500 W (~13 A @ 115 V) | ≈ 3,000 W | Dometic 13.5K BTU class official spec (FreshJet 5 Series 15K page, built-in hard start) |
| Window AC — 8,000 BTU (typical) | ≈ 700–800 W | ≈ 1,500 W | Typical label range (illustrative — check your unit's official label) |
Surge vs steady: why the inverter matters
We size inverters as max(steady load × 1.25, actual surge) (site-wide engine rule, unit-tested). For the 13.5K BTU RV unit: max(1,500 × 1.25, 3,000) = 3,000 W — surge-driven. A 2,800 W-running claim would imply ~24 A steady draw, well above the class spec; the official figure governs.
Battery side: at 1,500 W steady, every hour of AC costs 1,500 Wh before the 0.85 usable factor — a 1,024 Wh station covers under 45 minutes of RV AC. Window AC at ~750 W is 3–4× more practical.
Recommendations by AC type
8,000 BTU window AC
13.5K BTU RV rooftop AC
Mini / camping AC (portable units)
Frequently asked questions
Can a portable power station run an RV rooftop air conditioner?
Only if the station inverter handles the startup surge. A 13.5K BTU class RV rooftop AC draws about 1,500 W steady but peaks near 3,000 W at compressor start — none of the 1,800 W-class portable stations in our library can start it. You need an expandable system with a 3,000 W+ inverter.
How many watts does an 8,000 BTU window AC use?
Typical running draw is 700–800 W (illustrative — check your unit’s official label), with startup surge around 1,500 W. An 1,800 W inverter station such as the Bluetti AC180 or EcoFlow DELTA 3 can run one.
Why does startup surge matter more than running watts for AC?
Compressor start current briefly exceeds running current several times over. We size inverters as max(steady × 1.25, actual surge) — for a 13.5K RV AC that is max(1,500 × 1.25, 3,000) = 3,000 W, so a 3,000 W+ inverter is required regardless of the 1,500 W steady draw.
Does a hard start kit change the inverter size?
Yes — hard start capacitors reduce startup current. Current Dometic 15K rooftop units (FreshJet 5 Series) ship with built-in hard start; older units may need a retrofit kit. Always verify surge with the exact unit before sizing.
What battery capacity do I need to run a window AC overnight?
At ~750 W running for 8 hours, budget roughly 7,000 Wh per night after the 0.85 usable factor — a ~1,000 Wh station covers about 1 hour, so AC runtime needs whole-home-scale systems or solar recharge.