How Long Will a Powerwall 3 Last in an Outage? Real Load Profiles
13.5 kWh goes a long way on essentials and very fast on central AC. Hours of backup for five typical homes, and what 11.5 kW and 185 LRA really mean.
Updated October 27, 2026 · By the OutageWatt team · How we calculate
In short
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Five homes, one battery
| What stays on | Per day | 1 Powerwall 3 | 2 units | 1 unit + 6 kW solar |
|---|---|---|---|---|
| Fridge, Wi-Fi, lights, phones790 W run · 3.0 kW start | 1.7 kWh | 7.1 days | 14 days+ | 14 days+ |
| + 1/2 HP sump pump in a storm1.8 kW run · 4.0 kW start | 3.8 kWh | 3.2 days | 6.4 days | 14 days+ |
| Winter: gas furnace blower + essentials1.7 kW run · 4.0 kW start | 12.3 kWh | 24 h | 47 h | 14 days+ |
| Window AC 8 h/day + essentials4.0 kW run · 8.0 kW start | 27.7 kWh | 11 h | 21 h | 11 h |
| Central AC 2 ton, 8 h/day + essentials4.6 kW run · 9.5 kW start | 32.1 kWh | 9.1 h | 18 h | 9.1 h |
13.5 kWh usable per unit, 90% efficiency, outage starting at 6 p.m. Solar: clear days, sine curve at 75% of rating; it only helps after sunrise, so a battery that runs flat overnight shows the same time with or without panels. Appliance figures are conservative generator-chart values.
11.5 kW and 185 LRA: what they mean
Tesla's datasheet gives Powerwall 3 up to 11.5 kW of continuous output and a motor-start rating of 185 locked-rotor amps (LRA). Continuous output decides how much can run at once; the LRA rating decides which motors it can start. Central AC condensers print their LRA on the label outside: if it is below 185, one Powerwall 3 should start it.
Energy is the limit
With 11.5 kW available, a Powerwall 3 rarely runs out of power before it runs out of energy. The table shows how quickly AC eats 13.5 kWh. If you want AC through a long outage, you need solar, a second unit, or the discipline to run it a few hours a day. Compare it with Enphase and FranklinWH on our home battery page.
Frequently asked questions
How long will one Powerwall 3 power a house?
It depends entirely on what's on. Running an average US home's full load (about 28 kWh a day per the EIA), one Powerwall 3 lasts roughly 10 h. Limited to a fridge, Wi-Fi, lights and phones, it lasts about 7.1 days.
Can a Powerwall 3 run central air?
It can deliver 11.5 kW continuous and is rated to start motors up to 185 locked-rotor amps, which covers many central AC units. Check the LRA on your outdoor unit. Running AC drains it fast; see the table.
Does solar recharge a Powerwall during an outage?
Yes, Powerwall 3 has a built-in solar inverter and keeps charging from your panels while the grid is down. On clear days a typical rooftop system can refill it, which is how homes ride out multi-day outages.
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OutageWatt is independent and not affiliated with any brand named here. Specs come from makers' spec sheets and are dated; anything wired into your home needs a licensed electrician and a transfer switch or interlock. Never backfeed through an outlet.