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What size power station do I need to run a window air conditioner?

Q: What size power station do I need to run a window air conditioner?

Plan on a power station with at least 2650 watt-hours of capacity and 500W continuous / 1500W surge output to run this for 4 hours. A Extra-large (≈3,600Wh) covers it, running the load about ~5.5 h on a charge.

A small 5,000 BTU window unit is the most realistic AC-on-battery scenario. It's within reach of a large station for a few hours — enough to fall asleep in a heat wave — but AC is an energy-hungry load, so runtime is measured in hours, not nights.

The load

Window AC (5,000 BTU) — 500W running, 1500W starting

POWER PLATE1 LOAD · 4 H RUNTIME

Continuous draw

500 W

Startup surge

1,500 W

Energy for 4 h

2,353 Wh

Buy at least

2,650 Wh

Look for ≥2,650Wh capacity, ~500W continuous / 1,500W surge or better.

Field note: Size to the compressor's start-up surge, then expect a large station to give you a few hours. A modern inverter (variable-speed) window unit sips far less than a fixed-speed one and stretches that runtime meaningfully. Daytime solar is what makes AC-on-battery genuinely practical.

Right size: Extra-large (≈3,600Wh) · 3,600W

Typical price $2,000-3,200 · e.g. EcoFlow Delta Pro 3, Bluetti AC300 + B300 module

A fridge and essentials for a day or more, a 120V window AC, a home office through a long outage. Approaching generator money; the value comes from pairing it with solar so it refills each day.

Runs this load ~5.5 h on a full charge.

See current prices on Amazon

One size up: Expandable home backup (≈6,000Wh+) · 5,000W

Typical price $3,500-6,000+ · e.g. EcoFlow Delta Pro Ultra, Bluetti AC500 + B300S (stackable)

Backing up whole circuits through a transfer switch; add battery modules for days of autonomy, especially with solar. A home-backup system, not a grab-and-go unit. For 240V loads or true whole-home coverage, compare against a standby generator.

Runs this load ~9.2 h on a full charge.

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Adjust for your setup

Different loads or runtime? Uncheck and re-check below and drag the runtime slider — the plate recomputes live.

POWER PLATE1 LOAD · 4 H RUNTIME

Continuous draw

500 W

Startup surge

1,500 W

Energy for 4 h

2,353 Wh

Buy at least

2,650 Wh

Look for ≥2,650Wh capacity, ~500W continuous / 1,500W surge or better.

Capacity includes inverter loss (~15%) and a usable-charge margin, so the station isn't run flat. A solar panel or vehicle charge extends runtime past this number.

How long do you need to run it? 4 h

Kitchen Refrigerator (full-size) 300W run / 1500W start Mini fridge 90W run / 700W start Chest freezer 250W run / 1200W start Microwave (1000W) 1400W run Electric range (one burner) 1500W run Coffee maker (drip) 900W run Toaster 1100W run Electric kettle 1400W run Dishwasher 1300W run / 1500W start Instant Pot / multicooker 1000W run

Heating & cooling Window AC (5,000 BTU) 500W run / 1500W start Window AC (8,000 BTU) 800W run / 2200W start Window AC (12,000 BTU) 1100W run / 3000W start Central AC (3-ton) 3500W run / 8500W start Space heater (1500W) 1500W run Furnace blower fan (gas furnace) 600W run / 1600W start Heat pump (2-ton) 2500W run / 6000W start Box fan 100W run / 150W start Ceiling fan 75W run / 100W start

Pumps & well Sump pump (1/3 HP) 800W run / 1500W start Sump pump (1/2 HP) 1050W run / 2200W start Well pump (1/2 HP) 1000W run / 2100W start Well pump (1 HP) 2000W run / 4000W start Sewage ejector pump (1/2 HP) 1000W run / 2200W start

Electronics TV (55" LED) 80W run Wi-Fi router + modem 15W run Laptop 65W run Desktop PC + monitor 350W run / 400W start Phone charger 10W run Starlink dish + router 75W run / 100W start

Medical & safety CPAP machine 60W run Oxygen concentrator 350W run / 600W start

Lighting LED lights (per room) 30W run

Laundry Washing machine 700W run / 1600W start Clothes dryer (electric) 5000W run / 6000W start Clothes dryer (gas) 700W run / 1800W start

Household Garage door opener (1/2 HP) 550W run / 1200W start Water heater (electric tank) 4500W run EV charging (Level 1, 120V) 1400W run

Tools & outdoor Circular saw 1400W run / 2300W start Air compressor (1 HP) 1500W run / 3000W start Welder (140A MIG) 3500W run / 4000W start

RV & camping RV air conditioner (13,500 BTU) 1300W run / 2900W start RV converter/charger 500W run Electric griddle 1200W run Slow cooker 250W run

Power stations that fit

Right size: Extra-large (≈3,600Wh) · 3,600W

Typical price $2,000-3,200 · e.g. EcoFlow Delta Pro 3, Bluetti AC300 + B300 module

A fridge and essentials for a day or more, a 120V window AC, a home office through a long outage. Approaching generator money; the value comes from pairing it with solar so it refills each day.

Runs this load ~5.5 h on a full charge.

See current prices on Amazon

One size up: Expandable home backup (≈6,000Wh+) · 5,000W

Typical price $3,500-6,000+ · e.g. EcoFlow Delta Pro Ultra, Bluetti AC500 + B300S (stackable)

Runs this load ~9.2 h on a full charge.

See current prices on Amazon

This site earns commissions from qualifying purchases made through links to Amazon and other retailers, at no extra cost to you. Wattage figures are typical estimates — actual draw varies by model. Always verify against your appliance's nameplate, and consult a licensed electrician for any panel or hardwired connections.