Runtime planning · Reviewed September 14, 2026
Runtime starts with usable AC energy, not the battery label.
A 1,000 Wh nameplate does not determine refrigerator runtime by itself. You need the energy the system can deliver to the appliance and a representative rate of refrigerator energy use. You must also confirm that the source can start and run the appliance.
Use quantities measured at the same boundary
For a simplified runtime estimate, divide usable AC energy delivered by the power station by the refrigerator’s representative average AC power:
Runtime (hours) = usable AC Wh ÷ average appliance W.
The numerator must describe delivered energy under relevant conditions, not simply rated internal battery energy. The denominator must represent the operating period, not just compressor-on watts. This is an energy-balance estimate and assumes that the observed behavior continues.
A sensitivity example, not a product test
The following values are deliberately hypothetical. They show how the answer changes; none is a claimed specification of a 1,000 Wh product.
| Usable AC energy | Average appliance demand | Calculated runtime |
|---|---|---|
| 600 Wh | 50 W | 12 hours |
| 800 Wh | 50 W | 16 hours |
| 800 Wh | 80 W | 10 hours |
Do not interpret the 600 or 800 Wh cases as recommended efficiency assumptions. If your product’s delivered energy is unknown, these remain examples and cannot resolve its runtime.
When you have a daily energy measurement
A hypothetical 1.44 kWh over 24 representative hours equals 1,440 Wh ÷ 24 = 60 W average. If a relevant source separately establishes 720 Wh usable AC energy, the conditional result is 12 hours. Different temperature, cycling or use may change that result.
The U.S. EIA explains W and Wh. The arithmetic here applies those units; it does not provide a universal refrigerator rating.
Why rated Wh divided by running W can mislead
That shortcut mixes internal stored energy with appliance consumption and can also treat a cycling load as constant. Conversion and operating losses affect available energy, while refrigerator behavior changes over time. Identify each assumption before presenting an hour figure.
Using a single delivered-energy test from a different load or operating period can also mislead. Inverter overhead becomes relevant during low-load and idle intervals. If you instead model separate efficiency, usable DC fraction and idle consumption in Backup Power Map, avoid counting the same loss twice.
Compare evidence before comparing runtime claims
Ask for the tested load, ambient conditions, starting charge, cutoff, output port and whether the result includes idle periods. A stated runtime without that context is hard to compare fairly. Our inverter-limit reference from Victron also explains why output and battery constraints must be considered separately.
No runtime table can establish food safety or electrical compatibility. A plan needs separate startup checks and an appropriate response if power ends sooner than expected. For a unit without relevant energy evidence, publish “runtime not established” rather than converting the battery nameplate into a promise.
Turn runtime math into a buying decision
Once you have usable AC energy and a representative refrigerator energy rate, compare the result with the sizing guide. If the plan reaches the 2kWh class, move to the current approved-partner comparison.
Turn the record into a backup plan
Start with the refrigerator sizing guide, then use Backup Power Map. For an example of the evidence to check, see our EcoFlow DELTA 3 Plus US research profile. The manufacturer link there is an ordinary link that currently earns no commission; it is not a claim that this product fits your appliance.