Core concept
AC inverter paths usually need a lower efficiency setting than direct DC.
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Inverter Efficiency Losses
AC is convenient, but the inverter changes battery energy into wall-style power and some energy is lost as heat.
Planning impact
USB-C or DC can help only when the device supports the voltage and cable safely.
What to verify
High efficiency settings make runtime look better than it may be.
Delivered Wh for an AC load = nominal Wh x AC efficiency x the other reserve, health, and temperature factors.
The Inverter Is A Conversion Step
An AC outlet is useful for household plugs, but it requires conversion from the station battery. The calculator makes that efficiency visible instead of hiding it.
Direct Paths Can Be Better
A supported DC or USB-C path may avoid the AC inverter. It is only appropriate when the device, voltage, connector, and cable match the manufacturer's guidance.
Do Not Overstate Efficiency
If you do not have a measured result, keep AC efficiency conservative. A few percentage points can change hours on overnight loads.
Worked example and a published reality check
This calculation is hypothetical, not a test of a named station. Change one assumption at a time. Keep reserve and output path the same when comparing, and use input watts rather than an appliance’s output rating.
- Battery capacity (Wh): 1,000 Wh · Device wattage (W): 15 W
- Efficiency (%): 85% · Reserve kept unused (%): 10% · Duty cycle (%): 100%
- Battery health (%): 100% · Cold weather loss (%): 0% · Output path: AC inverter
Estimated runtime: 51h
1,000 × 0.85 × 0.90 ÷ 15 = 51
The second calculation assumes 10 W of fixed battery-side overhead solely to illustrate the effect. This is not a measured specification. At small device loads, leaving the inverter on can matter more than a few efficiency percentage points.
Estimated runtime: 32.6 h
1,000 × 0.90 ÷ (15 ÷ 0.85 + 10) = 32.6
The same publisher reports different delivered energy for the same model at low and high AC loads. Read each Wh value together with its load and duration. The approximate watts cannot reconstruct the separately measured Wh and hours. Do not transfer the 380 W result to a router or CPAP setup.
EcoFlow DELTA 2
Third-party results apply to the listed model, output path and test load. The delta is against a fixed no-reserve planning formula, not an error score or a prediction at other loads. Missing test conditions remain unknown.
Swipe table sideways
| Test | Measured | default planning estimate | Vs estimate | Source |
|---|---|---|---|---|
| Runtime test (AC) Average test load: ~380 W test date unknown | 900 Wh 88% | 870 Wh | +30 Wh (+3%) | Outdoor Life Best Portable Power Stations of 2026 2026-01-09; accessed 2026-09-04 |
| Runtime test (AC) Average test load: ~34 W test date unknown | 690 Wh 67% | 870 Wh | -180 Wh (-21%) | Outdoor Life Best Portable Power Stations of 2026 2026-01-09; accessed 2026-09-04 |
Why rated Wh and delivered Wh differ
These are attributed third-party observations, not our hardware tests. Small continuous loads may deliver fewer Wh because an inverter remains active for longer. Efficiency also varies with load. Reported Wh and approximate watts × rounded hours need not agree; preserve the source's readings. Do not infer an inverter wattage from their difference.
Swipe table sideways
| Model | Below 100 W | 100 W or more | Difference at higher load |
|---|---|---|---|
| EcoFlow DELTA 2 outdoorlife.com | ~34 W · AC 690 Wh (67.4%) | ~380 W · AC 900 Wh (87.9%) | +210 Wh |
Same model, output and source series; temperature, battery endpoints and individual test dates remain unknown. These observations show a load association, not a controlled proof of its cause. Delivered Wh already include losses: do not subtract efficiency or overhead again.
Inverter draw: reported, with unresolved conditions
Outdoor Life attributes this AC inverter-and-port column to manufacturer replies. It is not an independently reproduced battery-side measurement. Load, interval, temperature and battery endpoints are unknown; these figures are not applied automatically in our calculator. Unavailable stays unknown. Recheck your exact setup before entering fixed overhead.
Swipe table sideways
| Model | Reported draw | Observation checked |
|---|---|---|
| EcoFlow DELTA 2 | 10 W · AC | Outdoor Life · 2026-09-30 |
Evidence and review
These sources support the definitions and planning method. Calculator results are still estimates, not measurements or guarantees.
WattRunTime publishes source-based editorial calculations. We do not claim to have laboratory-tested these products or to provide medical or certified engineering review. Sources support specific statements; automated checks validate structure and arithmetic, not product truth. Third-party measurements name their publisher.
- SUN Inverter technical specificationsVictron Energy · Technical manual — Open source
- Electric Vehicle Supply Equipment InfrastructureU.S. Department of Energy · Government reference — Open source
Compare AC And DC
Switch output path and efficiency in the calculator to see how AC, DC, and USB-C assumptions change the runtime range.
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Power station model
Battery capacity (Wh): 1024 WhContinuous output rating (W): 1800 WSurge output rating (W): 2700 W
Estimated runtime13h 3m8h 10m – 16h 13mEstimated runtime: 13h 3m, 8h 10m – 16h 13m
Output path
Estimated runtime
Within the tracked power limits; compatibility still needs checking
This is an estimate. Real runtime changes with load, temperature, battery age, AC/DC output, and device behavior. Runtime is conditional on successful startup, compatible voltage/connectors and sufficient output. Verify the actual device setup before relying on these hours.
13h 3mEstimated runtime: 13h 3mThis setup has comfortable headroom for overnight use, assuming the wattage estimate is realistic.
Conservative8h 10m
Estimated13h 3m
Optimistic16h 13m
These are calculated sensitivity cases, not a statistical confidence interval. Conservative uses lower efficiency and battery health, more reserve/temperature loss and higher load; optimistic changes these assumptions in the opposite direction.
- This is an estimate. Real runtime changes with load, temperature, battery age, AC/DC output, and device behavior. Runtime is conditional on successful startup, compatible voltage/connectors and sufficient output. Verify the actual device setup before relying on these hours.
- Within the tracked power limits; compatibility still needs checking
Show your work
Rated Wh is reduced by efficiency, reserve, battery health, and temperature before it is divided by average load.
- Rated battery
- 1024 Wh
- Usable energy
- 783 Wh
- 1024 Wh x 85% x 90% x 100% x 100%
- Running watts
- 60 W
- Average load
- 60 W
- Max surge
- n/a
- Fixed station overhead
- Unknown (not included)
- 60 W / 85% = 70.6 W battery draw; fixed overhead is unknown and excluded
- Estimated runtime
- 13h 3m
- 783 Wh / 60 W = 13h 3m
- Output path
- AC inverter
- Efficiency (%)
- 85
- Reserve kept unused (%)
- 10
- Battery health (%)
- 100
- Cold weather loss (%)
- 0
This link contains the numeric values you entered, but not custom load names.
Source-Backed Next Steps
Smallest matching record (8h)Jackery Explorer 600 Plus
WattRunTime.com
WattRunTime estimate
Estimated runtime
13h 3mThis setup has comfortable headroom for overnight use, assuming the wattage estimate is realistic.Usable energy783 Wh
Average load60 W
Fixed station overheadUnknown (not included)
Running watts60 W
Max surgen/a
Runtime range
Conservative8h 10m
Estimated13h 3m
Optimistic16h 13m
Show your work
Rated Wh is reduced by efficiency, reserve, battery health, and temperature before it is divided by average load.
Usable energy783 Wh1024 Wh x 85% x 90% x 100% x 100%
Fixed station overheadUnknown (not included)60 W / 85% = 70.6 W battery draw; fixed overhead is unknown and excluded
Estimated runtime13h 3m783 Wh / 60 W = 13h 3m
Assumptions
- 1024 Wh nominal battery capacity
- AC inverter output path
- 85% conversion efficiency
- 10% reserve kept unused
- 60 W average load from 1 load
- 100% battery health
- 0% temperature loss
- Fixed station overhead unknown; not included
Warnings
- This is an estimate. Real runtime changes with load, temperature, battery age, AC/DC output, and device behavior. Runtime is conditional on successful startup, compatible voltage/connectors and sufficient output. Verify the actual device setup before relying on these hours.
- Within the tracked power limits; compatibility still needs checking
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Capacity guide
Usable Capacity vs Rated Capacity
A 1,000 Wh label is the starting point, not a promise that 1,000 Wh reaches your device.
Margin guide
Reserve and Battery Health
A runtime plan is safer when it leaves margin for age, cold, changing load, and measurement error.
FAQ
Understand why AC inverter output usually delivers less usable energy than DC or USB-C paths in portable power station runtime estimates.
What AC efficiency should I start with?
The runtime calculator defaults to a conservative AC planning value. Raise it only when you have measured data or a trustworthy source for the same setup.
Is DC always better than AC?
No. DC helps only when the device supports the path safely. A wrong voltage, weak cable, or unsupported adapter is not a good trade for a longer estimate.