Backup Hours: Inverter Time
How many hours your battery is good for, with the appliances you actually have switched on.
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Screenshots
Features
The answer while the lights are still off
An ice storm takes the grid down and the only number that matters is hours. Tick the appliances that are running and Backup Hours estimates how long the battery holds under that exact load.
Set up the inverter once
Enter battery capacity in amp-hours, system voltage, battery type and how deeply you are willing to discharge. After that, outage nights are just checkboxes.
See what turning something off buys you
Uncheck the space heater and watch the estimate move before you actually shut it down. You get to choose what to sacrifice with a number in front of you, not a guess.
Countdown on the Lock Screen
A Live Activity keeps the remaining hours visible, so you are not unlocking the phone in a dark hallway to check. A Home Screen widget shows the same figure.
It learns your battery, not the label
A three-year-old battery does not hold what the case says. Log what actually happened after each outage and the app fits usable capacity to your own history.
Peukert, not simple division
Heavy loads pull a lead-acid battery down faster than capacity divided by watts suggests. The estimate accounts for that instead of flattering you.
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 switched on?
Add your inverter or UPS once — battery capacity in Ah, system voltage,
and how deeply you are willing to discharge it. Then tick the appliances
that are running. The remaining time updates as you switch things on and
off, so you can see what turning off the air conditioner buys you before
you turn it off.
A Live Activity keeps the countdown on the Lock Screen, so you are not
unlocking the phone in the dark to check.
Batteries age, and a three-year-old battery does not hold what the label
says. Log what actually happened after an outage and the app fits 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 arithmetic suggests.
Everything is an estimate to help you plan, not a guarantee. Battery
condition, temperature, and wiring all move the real number. Nothing is
measured by the phone and no sensor is required. All data stays on device.