Meet BackupHours — Outage runtime planner, fully offline

What BackupHours does

When the power goes out, the only question that matters is: how long until the fridge dies? BackupHours answers it in seconds.

BackupHours is an offline runtime planner for anyone with a home battery, solar setup, EV with vehicle-to-home, or a fuel generator. Instead of vague marketing numbers like "backup for your home," you build a real list of YOUR appliances and circuits — fridge, chest freezer, well pump, sump pump, CPAP, router, space heater, medical devices — each with its wattage and how many hours a day it actually runs. BackupHours then calculates exactly how many hours (or days) your stored energy will carry that load, accounting for inverter efficiency and battery depth-of-discharge.

The magic is load-shedding. Tag each circuit as Critical, Important, or Optional, then watch your runtime stretch as you shed the optional loads. See at a glance that running everything gives you 9 hours, but dropping the space heater and dryer buys you three full days on just the essentials. Build outage scenarios ahead of time — a 12-hour storm, a 3-day grid failure — so the plan is already made before you ever need it.

Model any energy source: a 13.5 kWh home battery, a stackable solar-plus-storage system, a 77 kWh EV battery feeding the house through V2H, or a 4,000-watt generator with a known fuel burn rate. Generators get fuel-aware runtime so you know how many gallons stand between you and a dead fridge. Solar users can add a daily recharge estimate to model multi-day off-grid resilience.

Because an outage is exactly when the internet is gone, BackupHours is built offline-first. No account, no login, no cloud, no subscription nagging you during an emergency. Everything you enter lives on this device. Open the app in a blackout and your whole plan is right there, instantly.

BackupHours is for the people who plan ahead. Maybe you live where the grid is shaky, where wildfire shutoffs or hurricane season are a yearly reality, or where you just installed a shiny new battery and want to know what it can really do. Maybe you rely on a CPAP, a fridge full of insulin, a sump pump that keeps the basement dry, or a well pump that is the only thing standing between you and no running water. For you, "how many hours" is not a hobby question — it is a safety question, and a vague spec sheet will not cut it.

The setup takes a few minutes once, and then it is done forever. Add your circuits, pick your priorities, save a scenario or two, and the plan lives quietly on your phone until the day you need it. No syncing, no re-downloading, no subscription that expires at the worst possible moment.

Whether you just installed a battery, drive an EV that can power your home, or keep a generator in the garage for hurricane season, BackupHours turns specs on a box into a number you can actually act on.

• Runtime calculator for battery, solar, EV V2H and generator sources • Build a custom appliance and circuit list with real wattages • Load-shed prioritization: Critical, Important, Optional tiers • Generator mode with fuel-aware burn-rate runtime • Solar recharge estimate for multi-day off-grid scenarios • Saved outage scenarios you can plan before the storm • Inverter efficiency and depth-of-discharge built into the math • 100% offline, no account, no subscription, works in a blackout

A look inside

Tap any screenshot to open the full-resolution version.

What's inside

• Source-aware runtime engine — Pick battery, solar, EV V2H or generator and enter usable energy; the engine computes hours/days against your total load with inverter efficiency and depth-of-discharge applied.
• Circuit & appliance list — Add each appliance or circuit with watts and daily run-hours, choosing from common presets (fridge, freezer, well pump, CPAP, router) or custom values.
• Load-shed planner — Tag circuits Critical, Important or Optional and toggle tiers off to instantly see runtime stretch, finding the minimum viable load for a long outage.
• Outage scenarios — Save named scenarios (12-hour storm, 3-day grid failure) with their own active circuits and source so the plan is ready before an emergency.

Why we built it

Battery and generator specs are marketed in vague kWh or 'whole-home' terms; owners can't tell how many hours their actual fridge, well pump and medical devices will run, or how to stretch that time by shedding loads.

What makes it different

Incumbents handle adjacent jobs but none do outage runtime math: Loadwise tracks the utility/rate schedule, GenLog tracks $/kWh costs, and ChargeBook logs charging sessions. Generic survival apps and battery-vendor companion apps either need the internet or only show a single canned 'backup hours' figure with no per-c…

Who it's for

Anyone who values a small, sharp, single-purpose tool that does one job well and stays out of the way.

In one line: Outage runtime planner, fully offline

Try it

See the Outage runtime planner, fully offline for the full feature list, the info table, and support links.

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