Should I reserve 20% battery?

A 10% to 20% reserve is a practical buffer for uncertainty, startup spikes, and avoiding a completely empty station during an outage.

Why is real runtime lower than the label capacity?

Battery label capacity is nominal. Inverter losses, DC conversion losses, reserve settings, cold weather, battery age, and changing device loads all reduce real runtime.

Why are surge watts different from running watts?

Motors and compressors can need a short startup burst. A station must handle both continuous running wattage and short surge wattage.

Can a power station run a refrigerator overnight?

Often yes, but the answer depends on battery Wh, fridge running watts, compressor duty cycle, room temperature, and startup surge. Always check surge capability.

How many watt-hours does a CPAP need overnight?

A CPAP without heated humidification may use roughly 240 to 480 Wh over eight hours. Heated humidifiers and tubes can raise that substantially.

Can I use this for medical backup planning?

Use it only as a planning estimate. For medical devices, follow the manufacturer guidance and keep a tested backup plan.

Can solar input extend runtime?

Yes, but solar output depends on panel wattage, sun angle, clouds, temperature, wiring, and charge controller limits. Do not count nameplate panel watts as guaranteed input.

How do you calculate portable power station runtime?

Use usable watt-hours divided by average load watts. For AC loads, a practical first-pass formula is battery Wh x efficiency x reserve factor divided by device watts.

Emergency Power Plan Builder

Turn outage essentials into a printable battery plan with load checklist, runtime target, solar offset, reserve, surge checks, and source-backed model starting points.

Loading emergency plannerPreparing calculator

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Outage target (hours)Reserve kept unused (%)Solar available (W)Peak sun hours per daySolar derate (%)

Recommended station size

6,930 Wh+

Includes 85% AC efficiency, 20% reserve, and a 15% planning buffer after solar offset.

Load energy4,488 Wh

Solar offset390 Wh

Running watts572 W

Startup surge2,900 W

Conservative7,970 Wh+

Estimated6,930 Wh+

Optimistic6,237 Wh+

Sensitivity scenarios, not a measured confidence interval: the endpoints change planning assumptions or apply the stated planning factors. They are not a guarantee or a probability of achieving this runtime.

Open in advanced runtime

Shareable plan link

Full-size refrigeratorCritical / 500 W / 2,900 W surge

QtyHours per day

Compressor cycling and startup surge matter more than label watts.

Router or modemConnectivity / 12 W

QtyHours per day

Count ONT, modem, router, and mesh nodes separately if needed.

LED lightsCritical / 10 W

QtyHours per day

Use the total number of bulbs or lamps you expect to run.

Phone chargingConnectivity / 15 W

QtyHours per day

Charging is usually intermittent, not a 24-hour steady load.

CPAP without heated humidifierMedical-adjacent / 40 W

QtyHours per day

Use manufacturer guidance for medical backup decisions. This is a comfort-focused estimate, not medical advice. Use the device manufacturer's battery guidance for critical backup planning.

Starlink MiniConnectivity / 32 W

QtyHours per day

Power path, cable, heat, and sky view can change real draw.

LaptopWork / 60 W

QtyHours per day

Use lower hours if you can charge once and work from battery.

Modem or fiber ONTConnectivity / 12 W

QtyHours per day

Keep it separate from the router so its steady draw is not missed.

Wi-Fi mesh nodeConnectivity / 10 W

QtyHours per day

Set quantity to the number of mesh nodes that must remain powered.

Computer monitorWork / 35 W

QtyHours per day

Brightness, size, refresh rate, and panel type change real draw.

Portable fanComfort / 35 W

QtyHours per day

Small fans can become important in warm-weather outages.

What To Check Next

Verify wattsOpen the wattage library

Compressor or pump?Check startup surge

Solar during outage?Check solar by location

Source-Backed Model Starting Points

These are formula-fit starting points from the local model database, not affiliate rankings.

EcoFlow DELTA Pro Ultra

6,144 Wh, AC output 7,200 W, confidence Verified.

Energy under selected assumptions: Below requirement (6931 Wh)
Continuous output: Meets numeric screen (572 W · AC)
Startup rating: Meets numeric screen
Voltage, profile, cable and polarity: Requires checking
Recharge / simultaneous operation: Requires checking
Weight: Requires checking (82.4 kg)

A numeric match is a shortlist, not confirmed compatibility. Fixed overhead may be unknown; verify exact ports, startup duration and charging behavior. Follow manufacturers for critical backup.

Model evidence and sources

capacity short by 786 Wh

LiPower T4 Master

6,144 Wh, AC output 4,200 W, confidence Estimated.

Energy under selected assumptions: Below requirement (6931 Wh)
Continuous output: Meets numeric screen (572 W · AC)
Startup rating: Meets numeric screen
Voltage, profile, cable and polarity: Requires checking
Recharge / simultaneous operation: Requires checking
Weight: Requires checking (61.4 kg)

A numeric match is a shortlist, not confirmed compatibility. Fixed overhead may be unknown; verify exact ports, startup duration and charging behavior. Follow manufacturers for critical backup.

Model evidence and sources

capacity short by 786 Wh

Goal Zero Yeti 6000X

6,071 Wh, AC output 2,000 W, confidence Verified.

Energy under selected assumptions: Below requirement (6931 Wh)
Continuous output: Meets numeric screen (572 W · AC)
Startup rating: Meets numeric screen
Voltage, profile, cable and polarity: Requires checking
Recharge / simultaneous operation: Requires checking
Weight: Requires checking (48.1 kg)

A numeric match is a shortlist, not confirmed compatibility. Fixed overhead may be unknown; verify exact ports, startup duration and charging behavior. Follow manufacturers for critical backup.

Model evidence and sources

capacity short by 859 Wh

Emergency and medical-adjacent loads need conservative planning. This tool is a planning estimate, not a safety guarantee. Check device labels, manuals, local guidance, and manufacturer backup instructions.

Recommended station size

6,930 Wh+Includes 85% AC efficiency, 20% reserve, and a 15% planning buffer after solar offset.

Load energy4,488 Wh

Solar offset390 Wh

Running watts572 W

Startup surge2,900 W

Outage target

24 hours

Loads

- Full-size refrigerator: 1 x 500 W, 33% duty, 24 active hours
- Router or modem: 1 x 12 W, 100% duty, 24 active hours
- LED lights: 3 x 10 W, 100% duty, 6 active hours
- Phone charging: 2 x 15 W, 100% duty, 2 active hours

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Will the battery last through the night?

Schedule up to three daily loads and two recharge windows for 1–7 days. Examples are user-adjustable assumptions, not forecasts. Equal start/end means all day; midnight-crossing windows are supported.

Battery capacity (Wh)DaysOutage starts at (0–23 h)Starting charge (%)Reserve kept unused (%)Battery health (%)Cold weather loss (%)Efficiency (%)Station fixed overhead (battery-side W)Conversion efficiency (%)Accepted charging power (W)

Daily load 1

WattsStarts at (h)Ends at (h)

Daily load 2

WattsStarts at (h)Ends at (h)

Daily load 3

WattsStarts at (h)Ends at (h)

Daily AC recharge

Accepted charging power (W)Starts at (h)Ends at (h)

Daily solar recharge

Accepted charging power (W)Starts at (h)Ends at (h)

Quiet hours: disable AC recharge

Starts at (h)Ends at (h)

I checked that this setup supports charging while supplying loads

Blank overhead is unknown and excluded; a blank input limit is unverified. Concurrent recharge is excluded until checked. Numeric screening does not verify startup, ports or medical backup.

Output stays enabled throughout. Charging watts are input-side; efficiency includes average taper/derating. Excess energy at full charge is discarded. Solar is an entered window, not a weather forecast. Reserve is retained; demand beyond it is unmet.

Reserve first reached after18.88h

Unmet demand, battery equivalent: 2,911.76 Wh

Conservative · Estimated · Optimistic

Read the values as a table

Swipe table sideways

Estimated battery charge over time
Elapsed time	Battery charge	Wh	Unmet demand, battery equivalent
0 h	100%	1,000 Wh	0 Wh
6 h	85.88%	858.82 Wh	0 Wh
12 h	71.76%	717.65 Wh	0 Wh
18 h	22.35%	223.53 Wh	0 Wh
24 h	10%	100 Wh	370.59 Wh
30 h	10%	100 Wh	511.76 Wh
36 h	10%	100 Wh	652.94 Wh
42 h	10%	100 Wh	1,147.06 Wh
48 h	10%	100 Wh	1,641.18 Wh
54 h	10%	100 Wh	1,782.35 Wh
60 h	10%	100 Wh	1,923.53 Wh
66 h	10%	100 Wh	2,417.65 Wh
72 h	10%	100 Wh	2,911.76 Wh

Verify your watts

Check the device label for running watts or input amps and volts.
Use a plug-in watt meter for AC loads when the result matters.
For cycling loads, measure long enough to capture on/off behavior.

Open wattage library

Check output path

AC inverter loads usually lose more energy than direct DC loads.
Keep reserve for cold weather, battery age, and load changes.
Do not treat label capacity as fully usable watt-hours.

Read the method

Check surge and output

Runtime does not prove a station can start a compressor or motor.
Compare device startup watts with the station surge rating.
Compare running watts with the station continuous output rating.

Check startup surge

Medical-device planning

Use this site as a planning estimate, not medical advice.
Follow the device manufacturer's battery guidance.
Test the full setup before relying on it overnight.