Section
Appliance backup
Battery backup for one appliance at a time: sump pumps, refrigerators, CPAP machines and well pumps, each with the same runtime table.
8 articles
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Battery backup for a garage door opener: one cycle is about 4 Wh, so buy for the start, not the hours
LiftMaster rates a 1/2 HP opener at 6 A and a cycle takes 22 seconds: ten a day is 44 Wh. What the built-in battery does, and five units that clear the start.
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Battery backup for a Wi-Fi router: the smallest unit that keeps the internet on, with the hours worked out
A router draws about 30 W by its adapter rating, so a 288 Wh unit is a working day and a 1 kWh unit a weekend. Five UPS-capable picks, sized from the label.
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Battery backup for a window AC: hours per kWh at 8,000 BTU, and the surge rule that decides the unit
An 8,000 BTU window AC draws 533 W running by its ENERGY STAR figure and cycles about half the time. Five units that clear the compressor rule, with hours.
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Battery backup for a refrigerator: how long a power station keeps food cold, from the EnergyGuide number
Hours a 1, 2 or 4 kWh power station keeps a refrigerator cold, sized from the EnergyGuide label, and five units with UPS switchover to do it unattended.
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Battery backup for a space heater: do not do this, and here is what to do instead
A 1,500 W heater empties a 2 kWh power station in about an hour. The arithmetic from the heater's nameplate, and the loads that keep a person warm instead.
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Generator for a well pump: battery or gas, sized from the motor's locked-rotor amps
Franklin publishes 5 A running and 32.2 A locked rotor for a 1/2 HP well pump motor. What that means for a generator, and the two batteries that clear it.
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Portable power station for a CPAP: how many nights, from ResMed's own power figures
Runtime for a CPAP with and without the humidifier, computed from ResMed's published draw, and five buyable units ranked for a night, a weekend and a week.
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Battery backup for a sump pump: what actually works, sized from the pump's own numbers
Sized from a real pump's nameplate, not the box: which power stations run a 1/3 HP sump pump through a night of rain, and for how long.