How many hours will your backup last?
Tick the appliances you need, pick the outage, and see runtime for four real batteries. Then print the plan for the fridge door.
Pick your outage
These four lengths are planning scenarios you choose, not forecasts. For context, EIA Table 11.3 (checked Oct 28, 2026) puts the average Texas customer at 2.2 hours without power in 2024 excluding major events and 21.2 hours including them (2025: 2.1 and 3.7 hours). Source. Set any number of hours here (1 to 720): hours
Tick what must stay on
| Appliance | Watts | Hours/day | Qty | Start W |
|---|
Watts, hours and quantity are editable and must be numbers above zero (hours up to 24). Every default has a source link. Fridges and freezers cycle, so we use 8 of 24 hours (Virginia Tech's one-third rule). "Start W" is the momentary starting load of a motor: blank means 3 times its running watts (Virginia Tech BSE-301).
Anything we missed (sump pump, oxygen concentrator, electric heat strips)
Read watts off the nameplate. Leave a row blank to skip it. Tick "motor / compressor" if it has one (default ticked, to be safe): its starting load counts toward the starting watts. If you know the starting watts (locked-rotor amps x volts), enter them.
W h/day
W h/day
Will it work?
Starting watts = everything running plus the biggest extra a single motor needs to start (starting watts minus running watts; 3 times running unless you set it; custom loads count). A rough rule, not a measurement. Batteries are compared with continuous watts because we could not verify a published surge rating for the EcoFlow and Anker units; Powerwall 3 uses its 185 A motor-start rating.
How long each option lasts
| Option | Runtime | Check |
|---|
Runtime = watt-hours x % usable / average load (50 to 100). 85% is our assumption for conversion loss; change it to your unit's spec. Nameplate specs from the makers' pages, see sources. Solar recharging is not counted.
Have another unit? Watt-hours continuous watts surge watts (optional) Leave all blank to skip.
Base Power: a Texas option
Base Power installs a 39.2 kWh home battery in parts of Texas and bills a monthly membership. Per Base's help page (read Oct 28, 2026) you pay a $50 refundable deposit, then installation of about $695 with $19 a month for one battery or $995 with $29 a month for two; the fee varies by utility area, and the page notes founding promotions. CoServ's page says up to 36 hours of backup with reduced energy use. Base does not publish a continuous kW rating on the pages we read, so the table shows runtime only and never says "fits": ask Base whether your load fits. Base help page, CoServ page.
Generator route
Tick loads to see generator ratings.
Generators kill people when used indoors. CPSC: more than 80 consumers die each year from CO poisoning caused by portable generators. Outside only, at least 20 feet from the house. Full rules.
Who this is for
Texas households who lived through the February 2021 freeze or a Houston-area storm outage and now want an answer to one question: for my appliances, how many hours will each backup option run? Not a "generator or battery" essay. Your list, your outage, the numbers.
What other pages do, and what this one does differently
Texas Power Cost
Its generator vs standby vs home battery guide (read Oct 28, 2026) compares the three on cost, run time and fit, using price ranges it labels illustrative national figures. It gives a rule of thumb of 8 to 12 kWh a day for a fridge, blower, lights and electronics. It has no appliance-by-appliance calculator. We show no prices because we have no sourced current ones.
Usable kWh
Its battery vs standby generator page (read Oct 28, 2026) sets a Generac 22 kW against Powerwall 3 and aPower 2 from spec sheets, with Powerwall runtime at two fixed loads (2.5 kWh a day and 28 kWh a day). It says its appliance pages carry runtime tables, and it discloses that it earns Amazon affiliate commissions. We put your whole appliance list in one calculator and print an outage plan.
Rhythm
Rhythm's battery vs generator guide comes from a retailer that sells its own battery. We are independent of any one product; any partner links will be disclosed and do not change the math.
Descriptions are of those pages as read on October 28, 2026. We also saw runtime calculators from Clear Energy Facts (it uses your Smart Meter Texas usage file) and Base Power (a battery seller) in search results and did not open them. If one is out of date, tell us at [email protected].