Running a Window AC on a Portable Power Station: Complete Sizing Guide

Window air conditioners fall into two categories with very different power demands: inverter compressor and standard (fixed-speed) compressor. Inverter models ramp up gradually and produce a modest startup surge. Standard models start their compressor from a dead stop and produce a much larger inrush current. That difference determines which power stations can handle each type. For the engineering explanation of why, see the Inverter AC vs Standard AC guide. This guide skips the theory and gives you the sizing answers.

All data below comes from OEM specification sheets and our database of 33 power stations evaluated against 49 devices.

Quick answer

• Inverter window AC (e.g. Midea 8,000 BTU): Most power stations above 1,000W continuous can run it. Surge is modest (~1,065W). The real question is runtime.
• Standard window AC (e.g. Frigidaire 8,000 BTU): Surge is the bottleneck (~2,010W at startup). You need a station with at least 2,400W peak, or a $50 soft-start device.
• Portable AC (12,000 BTU floor unit): Expect 3,750–4,071W surge and 1,250W+ running. Only large stations handle these. Always prefer a window unit if possible.
• Rule of thumb: Size for peak watts first (can it start?), then for watt-hours (how long does it run?). A station that cannot handle the startup surge is useless regardless of battery size.
• Overnight cooling on battery: Plan for 6–8 hours minimum. No single station under 2,000 Wh delivers that on a standard AC. You need solar recharging, a second battery, or smart thermostat management.

What SAFE, TIGHT, and FAIL mean in this guide: SAFE means the power station handles both the startup surge and running watts with margin to spare. TIGHT means it technically passes but the margin is thin — on a hot day with the compressor working hard, a TIGHT verdict can trip the inverter. FAIL means the station cannot start or sustain the AC at all.

The Two AC Models in Our Database

Inverter: Midea MAW08V1QWT (8,000 BTU, U-shaped)

This is the most popular inverter window AC in the US market. Its variable-speed DC inverter compressor adjusts speed continuously rather than cycling on and off. OEM specifications from the Midea product page and Amazon listing: 710W cooling watts (maximum draw at full capacity), 8.78A rated cooling amps, 115V. The CEER (Combined Energy Efficiency Ratio) is 15, which means the average consumption over a cooling cycle is approximately 533W (8,000 BTU divided by 15). But for power station sizing, you must use the maximum draw of 710W, not the cycle average. The power station inverter must handle the peak load, not the average.

Because inverter compressors ramp up gradually rather than starting from a dead stop, the startup surge is substantially lower than a fixed-speed compressor. Inverter AC surge is typically 1.1 to 1.5 times the maximum running watts. For the Midea MAW08V1QWT, this translates to an estimated surge of approximately 780W to 1,065W. We use 1,065W (1.5× factor) as the conservative sizing figure.

Standard: Frigidaire FHWC084WB1 (8,000 BTU)

This is a conventional fixed-speed compressor window AC. OEM specifications from the Frigidaire product page: 670W cooling watts, 5.9A rated cooling amps, 115V, CEER of 12. The compressor cycles on and off at full capacity rather than modulating speed.

Standard compressor startup surge is typically 3× the running watts for single-phase AC compressors. For the Frigidaire: 670W × 3 = 2,010W estimated startup surge. This surge lasts only a fraction of a second but must be handled by the power station’s inverter. If the inverter cannot deliver 2,010W instantaneously, it will trip its overload protection and shut down.

Full Compatibility Matrix

This table shows every power station in our database rated against both AC models. Verdicts use our standard criteria: SAFE means the power station’s surge capacity exceeds the AC’s startup surge by 15 percent or more. TIGHT means it passes but with less than 15 percent margin. FAIL means the power station cannot handle either the running watts or the startup surge.

Inverter AC: Midea MAW08V1QWT (710W running / ~1,065W surge)

*Bluetti AC200L: 2,400W is the base inverter rating. The 3,600W “Power Lifting” figure does not apply here. Power Lifting is designed for resistive loads (heaters, kettles). For motor-driven devices like AC compressors, use the base 2,400W rating.

Standard AC: Frigidaire FHWC084WB1 (670W running / ~2,010W surge)

*Bluetti AC200L base rating for motor loads. **Anker SurgePad: Anker states “heat-generating devices work best” with SurgePad, indicating it is optimized for resistive loads. For motor startup surges, the effective capacity may be lower than the 2,400W rating. The TIGHT verdict assumes SurgePad delivers the full 2,400W for the brief compressor startup, but we recommend testing before relying on this in a heat emergency.

Runtime Calculations

Passing the surge check only means the power station can start the AC. How long it runs depends on battery capacity and the AC’s sustained power draw.

The 0.70 derate factor accounts for inverter efficiency losses and the gap between nameplate capacity and real-world usable energy.

Inverter AC (Midea, 710W max draw)

Worst case = compressor at full speed the entire time (hot room, poor insulation). Pre-cooled room = room already at target temperature, compressor modulating at ~350W average. Real-world runtime falls somewhere between these columns depending on outdoor temperature, insulation, and room size.

Standard AC (Frigidaire, 670W)

Continuous = compressor never shuts off (extreme heat, poor insulation). 50% duty cycle = compressor runs half the time, fan-only the rest (moderate day, room already near target temp). On a truly extreme day, duty cycle approaches 100% and the continuous column applies.

Extending Runtime with Solar

Connecting solar panels while the AC runs partially offsets the battery drain. The math is simple subtraction:

Example: Midea inverter AC at 710W maximum draw with 400W of solar input during peak sun = 310W net drain. On an EcoFlow DELTA 2 Max (2,048 Wh), that extends runtime from 2.0 hours to approximately 4.6 hours during peak sun conditions. Outside of peak sun hours (early morning, late afternoon, cloudy conditions), solar input drops and net drain increases.

Two strategies that double your runtime

Raise the thermostat during the outage. Do not aim for 68°F on battery power. Set the thermostat to 78°F (25°C). It is survivable, it is what ENERGY STAR recommends for occupied homes, and it can triple your runtime compared to maintaining 68°F. Every degree warmer reduces compressor run time and extends your battery.

Soft-Start Option for Standard ACs

If your power station fails the surge check for a standard AC, a soft-start device can reduce the compressor’s startup surge by approximately 55 percent. This is an external module (typically $50 to $100) that wires between the power station and the AC unit.

With a soft-starter installed, the Frigidaire’s startup surge drops from approximately 2,010W to approximately 905W. This brings it within range of power stations that would otherwise fail:

The soft-starter does not reduce running watts, only the startup surge. The power station must still handle 670W continuous output to run the Frigidaire. For a detailed explanation of soft-start technology and installation, see the Soft-Start Devices Guide.

Portable ACs: A Harder Problem

Portable (floor-standing) air conditioners are significantly less efficient than window units and draw substantially more power. If your situation allows a window AC, always choose the window unit. A portable AC doing the same cooling job will drain your power station roughly twice as fast due to the single-hose or dual-hose design inefficiency.

Typical 12,000 BTU portable AC specifications from our database: 1,250W to 1,357W running watts, with startup surges of 3,750W to 4,071W (3× ratio for standard compressor models).

Runtime on a 12,000 BTU portable AC is also significantly shorter. At 1,300W average draw on an EcoFlow DELTA Pro 3 (4,096 Wh): 4,096 × 0.70 / 1,300 = 2.2 hours. This is expensive, short-duration emergency cooling only.

If you must use a portable AC on battery power, the soft-start approach works here too. A 4,071W raw surge reduced by 55 percent (× 0.45) becomes approximately 1,832W, bringing it within range of the EcoFlow DELTA 2 Max and several other mid-range stations. But the high running watts (1,250W+) still limit runtime severely.

If you insist on running a portable AC on battery:

• Prefer dual-hose models. Single-hose portable ACs create negative pressure in the room, pulling hot outside air through gaps. Dual-hose units are significantly more efficient and reduce compressor runtime.
• Prefer inverter portable models if available. Inverter portables have lower surge and variable-speed operation, same advantages as inverter window units.
• Budget 1,250–1,350 Wh per hour of cooling. That is roughly double what a comparable window AC consumes for the same cooling output. If you have the option to install a window unit, the math strongly favors it.

The Bottom Line

For battery-powered window AC cooling, the single most impactful decision is choosing an inverter AC unit. The Midea MAW08V1QWT (or comparable inverter model) has lower running watts, lower startup surge, and variable-speed operation that extends battery runtime. It is compatible with every power station in our database rated above 1,000W continuous, and it delivers meaningfully longer runtime than a standard AC on the same battery.

If you already own a standard window AC, a soft-start device for $50 to $100 dramatically expands the range of compatible power stations and provides a safety margin against startup failures.

Check your specific AC model against your specific power station using our compatibility calculator before making any purchase.

Recommended Reading

For the technical explanation of inverter vs standard compressor technology, see the Inverter AC vs Standard AC guide.

For power station options optimized for window AC use, see the Best for Window AC page.

For portable AC compatibility, see the Best for Portable AC page.

For a full explanation of surge watts and why they matter, see the Surge Watts Explained guide.