What size battery runs an air conditioner during an outage?

Air conditioning is where battery backup marketing and physics part company. The capacity question is easy and the surge question is hard, and most buying advice answers only the first. This guide works from published numbers on both sides: what air conditioners actually draw, running and starting, and what these five power stations publish for continuous output and surge. Every figure is a manufacturer datasheet claim quoted with its stated basis. We have not lab-tested any of these units, and the Amazon links above are affiliate links, disclosed at the top of this page.

Two completely different appliances

"Air conditioner" covers two machines with almost nothing in common electrically.

Window and through-wall units run on ordinary 120V circuits. LG publishes 660 watts and 6.2 rated amps at 115V for the 8,000 BTU LW8016ER, which it rates for rooms up to 340 square feet; 730 watts and 6.4 amps for the 8,000 BTU LW8024RSMY; and 990 watts and 9.3 amps at 115V for the 12,000 BTU LW1216ER and LW1217ERSM, rated to 550 square feet. Those are running figures. LG does not publish a locked rotor figure for these units in its consumer spec sheets, so the startup draw is not something we can put a number on, though it is far smaller than a central condenser's because the motor is far smaller.

Central systems run on 208/230V split phase and are sized in tons. Goodman's current GLXS3B specification sheet (SS-GLXS3B-R32, 04/26) gives compressor rated load amps of 8.2 with locked rotor amps of 41.2 on the 1.5-ton GLXS3BN1810A, and rated load amps of 23.9 with locked rotor amps of 148.0 on the 5-ton GLXS3BN6010A, both at 208/230V single phase. Locked rotor amps is the manufacturer's figure for the maximum current the motor can draw, and as Micro-Air puts it in its own technical explanation, during a start you can expect the compressor to draw this current from the supply.

Two notes on those figures before we use them. They are compressor RLA and LRA from the sheet's own columns, not the minimum circuit ampacity, which is a larger number on the same page and sizes the wire rather than the motor. And LRA varies by series even at the same tonnage: Goodman's higher-efficiency GLXS5B publishes 44.3 LRA at 1.5 tons and 178 LRA at 5 tons. Your own condenser's nameplate is the figure that governs.

The gap between those two lines is the whole article. A 990 W window unit and a 5-ton condenser are not variations of the same problem.

The surge gate, in volts times amps

Convert the locked rotor figures at 240 V and the picture is immediate:

• 1.5-ton condenser, 41.2 LRA. About 9.9 kVA at the starting instant.
• 5-ton condenser, 148.0 LRA. About 35.5 kVA at the starting instant.

Now the published surge ratings on this page. EcoFlow publishes 8,000 W for the DELTA Pro 3 and 10.8 kW for the DELTA Pro Ultra. Jackery publishes 14,400 W for the Explorer 5000 Plus. BLUETTI publishes 3,900 W of power lifting for the Elite 200 V2. Anker publishes no surge figure for the F3800 Plus in its spec table, publishing 9,000 W only for the base F3800, a different configuration, so we print none for the Plus and treat its 6,000 W maximum as the number to size against.

Set those against the two conversions above. The 5-ton figure, at about 35.5 kVA, is nearly two and a half times the highest published surge here. Even the 1.5-ton figure, at about 9.9 kVA, sits above the DELTA Pro 3's 8,000 W surge, and is cleared on paper only by the Explorer 5000 Plus and the DELTA Pro Ultra. And clearing a surge figure on paper is not the same as a manufacturer stating the unit will start that compressor, which none of them does.

What a soft start changes

A soft starter sits at the compressor and ramps the winding current up over several cycles instead of applying it at once. Micro-Air publishes that its EasyStart creates a very smooth start that reduces the peak current by 50 to 70 percent, and gives the RV example of a 16 KBTU rooftop compressor rated around 50 to 60 amps LRA starting on under 20 amps.

Apply the published range to the Goodman figures, and label the assumption: we are using Micro-Air's own 50 to 70 percent range, applied to another manufacturer's published LRA, which is arithmetic rather than a tested pairing.

• 5-ton, 148 LRA. A 70 percent reduction leaves about 44 amps, roughly 10.7 kVA at 240 V. A 50 percent reduction leaves about 74 amps, roughly 17.8 kVA. So the best published case lands just past the DELTA Pro Ultra's 10.8 kW surge and the worse case exceeds every unit here.
• 1.5-ton, 41.2 LRA. A 70 percent reduction leaves about 12 amps, roughly 3.0 kVA. A 50 percent reduction leaves about 21 amps, roughly 4.9 kVA. Both are inside the DELTA Pro 3's published 8,000 W surge.

That is the honest version of the soft-start story: it makes a small condenser plausible to start and does not make a large one a portable job.

Runtime, which is the second problem

Starting is a moment. Cooling is hours. Two conversions again, with the assumption stated: rated watt-hours are stored energy, not delivered energy, and none of these makers publishes a single household efficiency figure, so this guide assumes 85 percent delivery throughout.

Window unit on a portable. The DELTA Pro 3's 4,096 Wh at 0.85 is about 3,482 Wh. Against LG's published 990 W for the 12,000 BTU unit, that is about 3.5 hours of continuous compressor running, or about 5.9 hours if you assume a 60 percent duty cycle, an assumption about your room and thermostat rather than a spec. The Elite 200 V2's 2,073.6 Wh at 0.85 is about 1,762 Wh, which is about 1.8 hours continuous on that same 990 W unit, or roughly 3.0 hours at the same duty-cycle assumption. On the 8,000 BTU unit's published 660 W, the Elite 200 V2 gives about 2.7 hours continuous and about 4.4 hours at 60 percent duty.

Central AC on a portable, even if it started. Take the 1.5-ton compressor at its published 8.2 rated load amps, about 2.0 kVA at 240 V, and add an air handler blower, which we assume at 500 W since it is a separate component with its own nameplate. That is roughly 2.5 kW. The DELTA Pro 3's 3,482 Wh delivered runs it about 1.4 hours continuously, or about 2.3 hours at 60 percent duty. The DELTA Pro Ultra's 6,144 Wh per battery, at 0.85, is about 5,222 Wh, or roughly 2.1 hours continuous on the same load. That is the smallest residential central system, on the largest units here, for a couple of hours.

Which is the point. Even where the surge math can be forced to work with a soft start, the energy math says a portable power station cools a house for a fraction of an afternoon, not for an outage.

Which loads belong on which hardware

• A window or through-wall unit: any pick on this page carries it. The Elite 200 V2 is the smallest that does so with published headroom, and the DELTA Pro 3 is the one that gives you hours rather than an hour.
• A 240V load on a circuit, with an electrician: the Anker SOLIX F3800 Plus delivers its 6,000 W maximum through the L14-30R port, and the Jackery Explorer 5000 Plus bundles the Smart Transfer Switch that makes circuit-level hookup a single order rather than two.
• The smallest central systems, with a soft start and a transfer switch: the DELTA Pro Ultra is the only unit here whose published surge sits in the same range as a soft-started small condenser, and it is a two-piece inverter-plus-battery system rather than a suitcase.
• A whole home with real air conditioning: an installed system, and it is a genuinely different answer rather than a bigger version of the same one. Compare continuous and peak ratings directly on our batteries page, including the Savant Power Storage 20 at 12.5 kW continuous and 30 kW peak, the FranklinWH aPower 2 at 10 kW continuous and 15 kW peak, and the Fortress Power eVault Max 18.5 at 9.2 kW continuous and 12 kW peak. Then read the Tesla Powerwall 3 row differently: it publishes 11.5 kW continuous and no peak watt figure, but its datasheet does publish a Load Start Capability of 185 LRA. Tesla is the only maker in our tracked set that publishes a motor-start rating at all, on the Powerwall 3 and, at 88 to 106 LRA, on the discontinued Powerwall 2. It is the only published figure here that speaks directly to a compressor. Ask any installed-system vendor for the equivalent number before you believe a whole-home air conditioning promise.

The claim that does not hold up

The claim worth naming plainly is the one that appears in retail copy and video reviews: that a portable power station is a whole-home air conditioning backup. On the published numbers it is not, for three separate reasons, any one of which is sufficient. The locked rotor draw of a 5-ton central condenser, at about 35.5 kVA, exceeds every surge rating on this page by more than a factor of two. Feeding a 240V central system requires an electrician-installed transfer switch or backup panel, which is the installed path arriving through the back door. And even granting both, the delivered watt-hours run a small central system for about one to two hours. A power station that carries a window unit through the hottest part of an evening is a genuinely useful thing. It is a different claim from cooling a house.

The honest limits

Every figure above comes from a manufacturer's published specification, quoted with the basis the maker states. The duty-cycle and blower figures are labelled assumptions, and the soft-start arithmetic applies one manufacturer's published reduction range to another manufacturer's published locked rotor amps, which is not a tested pairing. Your own condenser's nameplate is the number that governs, not the model we quoted, and reading it is a five-minute job that beats any general estimate. Prices on these products move often, which is one reason we publish none here. If your real question is what an installed system would need to carry your cooling load, start with sizing in kWh and then the whole-home backup guide.