How Long Does a Home Battery Last? And How Many Do You Need?

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The power went out at 7 p.m., and the house kept humming: the fridge, the lights over the kitchen table, the Wi-Fi the kids won’t live without. By midnight, though, you’re watching the battery percentage on your phone app and wondering: how far will this get us? Will it make it to morning? To Thursday?

Short answer: one 13.5 kWh home battery, like a Tesla Powerwall 3, runs an average U.S. home for roughly 9 hours, or essentials only (fridge, freezer, Wi-Fi, lights, phones) for four to five days, by our estimate. Most homes need one battery for essentials, two or three for a whole-house day. The batteries themselves are warrantied for 10 to 15 years.

Below: the simple math for your own home, a runtime table for the common systems, how to work out how many batteries you need, and how many years a battery lasts before it wears down.

Prices change often. The prices below are what we saw at the maker or a major retailer in October 2026; check the current price before you buy. Installer systems are priced by quote.

How long does a home battery backup last in an outage?

It comes down to two numbers: how much energy the battery holds (kWh) and how much your home uses while the power is out (kWh per day). The math:

Hours of backup ≈ available kWh ÷ kWh you use per day × 24

We count about 85% of the maker’s capacity as available. Some energy is lost turning stored power into household current, and many owners keep a small reserve. NREL uses 85% as a typical round-trip efficiency for home batteries, so this is a fair, slightly cautious figure.

Next, what you use. The EIA says the average U.S. home bought 10,791 kWh of electricity in 2022, about 30 kWh a day, but it ranges from about 17 kWh a day in Hawaii to about 40 in Louisiana. In an outage you can cut that a lot. Here’s a sample day of essentials:

Load (source of the number)	Energy per day
Full-size top-freezer fridge (median ENERGY STAR model, 363 kWh a year)	≈1.0 kWh
Chest freezer (median ENERGY STAR full-size model, 218 kWh a year)	≈0.6 kWh
Modem and router, 20 W together, 24 hours (example; check your adapters’ labels)	≈0.5 kWh
Five 9 W LED bulbs, 5 hours each (bulb label)	≈0.2 kWh
Phones and a laptop (65 W charger, 2 hours)	≈0.1 kWh
Essentials total	≈2.4 kWh
Gas furnace blower, 500 W for 6 hours on a cold day (example; check your furnace label)	≈3.0 kWh
Sump pump, Zoeller M53: 9.7 A × 115 V ≈ 1,116 W, 1 hour of pumping in total (Zoeller specs)	≈1.1 kWh
Essentials + furnace + sump pump	≈6.5 kWh
Average whole U.S. home (EIA, 2022)	≈29.6 kWh

Now divide. Our estimates for popular systems, with no solar recharging:

Battery (rated kWh → ≈ available)	Essentials (2.4 kWh/day)	+ furnace and sump (6.5 kWh/day)	Average whole home (29.6 kWh/day)
BLUETTI Apex 300 (2.76 → 2.35)	≈23 hours	≈9 hours	≈2 hours
Jackery HomePower 3000 (3.07 → 2.61)	≈26 hours	≈10 hours	≈2 hours
Enphase IQ Battery 5P (5 → 4.25)	≈1.75 days	≈16 hours	≈3.5 hours
EcoFlow DELTA Pro Ultra or Anker SOLIX E10, one battery (6.14 → 5.2)	≈2.1 days	≈19 hours	≈4 hours
Enphase IQ Battery 10C (10 → 8.5)	≈3.5 days	≈31 hours	≈7 hours
Tesla Powerwall 3 (13.5 → 11.5)	≈4.7 days	≈1.75 days	≈9 hours
FranklinWH aPower 2 (15 → 12.75)	≈5.2 days	≈1.9 days	≈10 hours
Two Powerwall 3 (27 → 23)	≈9.4 days	≈3.5 days	≈19 hours
Anker SOLIX E10 with five batteries (30.7 → 26.1)	≈10.7 days	≈4 days	≈21 hours

These are our estimates, not maker figures. Real runtime changes with the weather, the age of the battery and how often the furnace, pump or fridge kicks on. Two things stretch it a lot:

• Solar. Panels refill the battery during the day. A Lawrence Berkeley National Laboratory and NREL study (2022) found that solar plus just 10 kWh of storage could fully cover basic needs through a three-day outage in virtually every U.S. county, as long as heating and cooling are left off. With heating and cooling backed up, a 30 kWh system kept critical loads running for most homes in 7 of the 10 historical outages studied. Snow-covered panels and dark winter days cut that.
• Load control. Skip the big users: electric water heaters, dryers, ranges and electric heat. Many systems let you set a backup reserve and turn off circuits from an app. Ready.gov notes a closed fridge keeps food cold for about four hours and a full freezer holds its temperature for about 48 hours, so they don’t need power every minute.

How many batteries do I need to power my house?

Work through four steps. An installer will do this too, but knowing the answer first helps you compare quotes.

1. Find your daily use

Look at your electric bill or utility app for kWh per month, then divide by 30. Use a summer month if you have central air and a winter month if you heat with electricity. No bill handy? The U.S. average is about 30 kWh a day (EIA).

2. Decide what to back up

Whole-home backup means everything; essential-loads backup means the electrician moves a handful of circuits (fridge, some lights and outlets, furnace, sump or well pump, internet) to a backup panel. Essentials often run 2 to 7 kWh a day, as in our table; a whole home runs 20 to 40 or more.

3. Pick how many days, then divide

Batteries needed ≈ (daily kWh × days) ÷ (one battery’s kWh × 0.85), rounded up. Check your area’s history; the EIA says U.S. customers averaged about 11 hours without power in 2024, mostly from major hurricanes, but South Carolina customers averaged nearly 53 hours.

• Essentials for 3 days (2.4 kWh × 3 = 7.2 kWh): one 10 kWh-class battery, or one Powerwall 3.
• Essentials, furnace and sump for 2 days (6.5 × 2 = 13 kWh): two 10 kWh-class batteries, or one Powerwall 3 plus solar.
• An average whole home for 1 day (29.6 kWh): about 2.6 Powerwall 3 units, so three, or one with enough solar to refill it daily.
• An average whole home for 3 days without sun (about 89 kWh): eight Powerwall-size batteries. This is where a generator, or a battery plus generator, usually makes more sense.

4. Check power (kW) and starting surge

Energy (kWh) is how long; power (kW) is how much at once. Add up what runs together, and check motor starts: central air, well pumps and sump pumps pull a big burst for a moment, listed as LRA (locked-rotor amps) on the nameplate. The Powerwall 3 lists 11.5 kW continuous and 185 A LRA, FranklinWH’s aPower 2 10 kW and 185 A, Enphase’s IQ Battery 5P only 3.84 kVA and 48 A, so small modular batteries may need to be stacked just to start an AC. Sometimes you add a battery for power, not energy.

How many years does a home battery last?

The second meaning of “how long does a home battery last” is lifespan. Most home batteries are warrantied for 10 to 15 years, and EnergySage says most last about 10 to 15 years. NREL assumes a 15-year life in its cost studies. A battery doesn’t die suddenly; it slowly holds less. Warranties promise a minimum capacity at the end, and they aren’t written the same way:

Battery	Warranty (maker)	Capacity promised or rated
Tesla Powerwall 3	10 years (4 years if kept offline)	70% at 10 years; unlimited cycles for solar self-use and backup
Enphase IQ Battery 5P / 10C	15 years or 6,000 cycles	60% at end of warranty
FranklinWH aPower 2	15 years or 60 MWh of throughput	At least 70%
Generac PWRcell 2	Battery modules 10 years or 7.56 MWh	Not stated on the spec sheet we read
EcoFlow DELTA Pro Ultra	5 years	Rated 80% after 3,500 cycles
Anker SOLIX E10	5 years	Rated 80% after 4,000 cycles
Jackery HomePower 3000	3 years, +2 when bought at jackery.com	Not stated in our records
BLUETTI Apex 300	Not confirmed on the maker page	Rated 80% after 6,000+ cycles

Cycles add up slowly for backup-only use; a battery that only covers outages may cycle a few dozen times a year. Daily solar cycling is the real wear: one cycle a day for 6,000 cycles is about 16 years. What shortens battery life is heat, time spent fully charged and, for lithium batteries, charging below freezing (Battery University). Tesla lists the Powerwall 3’s operating range as –4°F to 122°F, with reduced performance above 104°F. Give the installer a shaded, ventilated spot, and keep the warranty paperwork: some warranties depend on the system staying online.

Home batteries worth a look

Tesla, Enphase and FranklinWH batteries are sold and installed through certified installers, not on Amazon; their cards link to the maker. The plug-in systems can be bought online, but any connection to your house wiring is installed by a licensed electrician, with a permit where required.

Tesla Powerwall 3: best single battery for most homes

13.5 kWh and 11.5 kW in one unit, with a built-in solar inverter; up to four Powerwall 3 units plus expansion packs per system. One covers essentials for days by our estimate; two or three cover a whole-house day. EnergySage lists a typical installed cost of $13,473 (2026).

• Good: strong motor-starting (185 A LRA); quiet; widely installed.
• Watch out: 10-year warranty is shorter than Enphase’s or FranklinWH’s 15; no list price.
• Best for: solar homes wanting the most backup from one box.

See it at Tesla

Anker SOLIX E10: best for adding batteries over time

A 7.68 kW, 120/240 V power module that takes one to five 6.144 kWh batteries (about 30 kWh), and three systems with Anker’s Power Dock reach 90 kWh. It’s rated for outdoor installation and doesn’t need solar. Anker says an electrician installs the Smart Inlet Box or Power Dock, and owners can add batteries afterward. Five-year warranty; rated 80% after 4,000 cycles.

• Good: start with one battery for essentials, grow toward whole-home.
• Watch out: shorter warranty than installer batteries; installation is extra.
• Best for: homes without solar that want to build up capacity.

Check the Anker SOLIX E10 price on Amazon

EcoFlow DELTA Pro Ultra: best plug-in system for big backup

Each LFP battery holds 6.144 kWh; one inverter (7.2 kW, 120/240 V) runs up to five. With EcoFlow’s Smart Home Panel 2, which EcoFlow says requires installation, up to three inverters reach 90 kWh. About $4,199 for one inverter and one battery at EcoFlow; 5-year warranty.

• Good: very expandable; takes up to 5,600 W of solar.
• Watch out: heavy pieces (battery about 112 lb); the panel and install add cost.
• Best for: several days of essentials without an installer battery contract.

Check the EcoFlow DELTA Pro Ultra price on Amazon

Jackery HomePower 3000: best budget essentials backup

3.072 kWh LFP and 3.6 kW of output. It isn’t expandable, so think a fridge, Wi-Fi and lights for about a day by our estimate, not a whole house. Jackery pairs it with a manual transfer switch for up to six circuits, installed by an electrician. About $1,349 at Jackery.

• Good: low cost; easy to move.
• Watch out: fixed capacity; Jackery says its stations aren’t recommended for medical devices.
• Best for: short outages in smaller homes.

Check the Jackery HomePower 3000 price on Amazon

There’s no federal tax credit for home batteries installed in 2026; the 25D credit ended for installations after December 31, 2025. Check DSIRE and your utility for state rebates and battery programs, and get two or three installer quotes.

Keep exploring

Our home battery backup guide covers the basics. Compare systems in the best home battery backup, price them with home battery backup cost, weigh home battery backup vs generator or look at Tesla Powerwall vs Enphase. For smaller needs, see portable power stations; for long outages, home generators. Learn how storage works in chemical energy and how panels refill it in solar energy, or browse home battery backup.

Home battery runtime and sizing questions

How long will a Tesla Powerwall run my house?

By our estimate, about 9 hours for an average U.S. home using 30 kWh a day, about a day and three-quarters for essentials plus a furnace and sump pump, and four to five days for essentials only. That counts about 85% of its 13.5 kWh as available and no solar. With solar recharging each day, it can go much longer.

How many batteries do I need to go off-grid?

Many more than for backup. You’d need enough storage for several cloudy days plus enough solar to refill it. For an average home at 30 kWh a day, three days of storage is about 89 kWh, roughly eight Powerwall-size batteries by our math. Most homes are better off staying grid-connected and backing up essentials.

Can one home battery run central air?

Sometimes. The battery needs enough continuous power and motor-starting current (LRA) for your unit; the Powerwall 3 lists 11.5 kW and 185 A, while smaller modules list much less. Even then, central air can drain one battery in a few hours. Ask your installer to read your AC’s nameplate and size for it.

How long does a home battery last before it needs replacing?

Usually 10 to 15 years. Tesla warranties the Powerwall 3 to keep 70% of its capacity for 10 years; Enphase and FranklinWH cover 15 years with cycle or throughput limits. After that the battery still works, just with less capacity. Heat and constant full charge age it faster.

Does a home battery work without solar?

Yes. It charges from the grid and waits for an outage, but it can’t recharge until the power returns, so it lasts only as long as its stored energy. Systems like the Anker SOLIX E10 and EcoFlow DELTA Pro Ultra don’t need solar. See the best home battery backup without solar.

Is a 10 kWh battery enough for a house?

For essentials, usually yes: about three and a half days of fridge, freezer, Wi-Fi and lights by our estimate, and Berkeley Lab found 10 kWh plus solar covers basic loads for three days almost anywhere in the U.S. For a whole home, no: 10 kWh is about a third of an average day’s use.