Backup Hours: Outage Time
Hours of battery remaining, counted against the appliances you have actually got running.
Download on the App Store
Screenshots
Features
A number when the grid is down
Freezing rain takes the lines out and everyone wants the same figure: how many hours? Check off what is running and Backup Hours estimates what the battery should manage on that load.
One-time inverter setup
Capacity in amp-hours, system voltage, battery chemistry and the depth of discharge you are willing to accept. After that, an outage is just a few taps.
Priced in advance
Uncheck the furnace fan or the well pump and the remaining hours change before you touch a breaker. Deciding what to drop is easier with the number visible.
Right on the Lock Screen
A Live Activity holds the countdown there, so nobody is unlocking a phone in a cold, dark basement to check. A widget carries the same figure on the Home Screen.
Calibrated from your own outages
A battery three winters old does not hold what the case claims. Log how each outage really went and the app derives usable capacity from your history instead.
Peukert, and the cold
A heavy draw takes more out of a lead-acid bank than capacity divided by watts implies, and a cold garage is not doing your battery any favours either. The estimate accounts for the load curve.
The power just went out. Backup Hours answers the only question that
matters right now: how many hours is the battery good for, with the
appliances you actually have running?
Set up your inverter or UPS once — battery capacity in Ah, system
voltage, battery type (flooded, AGM, gel or LiFePO4) and how deeply you
are willing to discharge it. After that you just check off whatever is
running. The remaining time recalculates with every tap, so you can see
what shutting off the space heater buys you before you shut it off.
A Live Activity keeps the countdown on the Lock Screen, so you are not
unlocking the phone in the dark just to check.
Batteries age, and a three-year-old battery does not hold what the label
claims. Log what actually happened after an outage and the app works out
your battery's real usable capacity from your own history, instead of
trusting the number printed on the case.
The estimate applies the Peukert relationship, so a heavy load is not
simply capacity divided by watts — drawing harder takes more out of a
lead-acid battery than the plain arithmetic suggests. That matters in a
cold snap, when the furnace fan and the well pump are both on the
inverter.
Everything here is an estimate to help you plan, never a guarantee.
Battery condition, temperature and wiring all move the real figure.
Nothing is measured by the phone, no sensor is required, and all data
stays on the device. Do not rely on this app to keep medical equipment or
anything else that must not stop running.