Portable power station runtime calculator
Power stations are rated in watt-hours. Divide by the watts you are running, take off the inverter loss for anything plugged into the AC outlets, and you have the hours.
Enter your measurements
More options: Efficiency · Duty · Reserve
- In hours and minutes
- 8 h 30 min
- Energy delivered to the load
- 850 Wh
- Average draw from the battery
- 117.6 W
1,000 Wh = 1,000 Wh available
100 W ÷ 85% inverter = 117.6 W
1,000 Wh ÷ 117.6 W = 8.5 hours (8 h 30 min)
Quick answers for common sizes
| Example | Answer |
|---|---|
| How long a power station runs a refrigerator | 12.9 hours on 1,000 Wh |
| How long a power station runs a space heater | 34 minutes on 1,000 Wh |
| What size power bank for a Starlink Mini | About 1,000 Wh for a full day; 300 Wh lasts about 7 hours |
| How long a power station runs an electric blanket | 4.3 hours on 500 Wh, 8.5 on 1,000 Wh |
Runtime by power station size
| Power station capacity | Runtime | Energy delivered to the load |
|---|---|---|
| 256 | 2.2 hours | 218 Wh |
| 500 | 4.3 hours | 425 Wh |
| 1000 | 8.5 hours | 850 Wh |
| 1500 | 12.8 hours | 1,275 Wh |
| 2000 | 17 hours | 1,700 Wh |
| 3600 | 30.6 hours | 3,060 Wh |
Worked examples: how long a power station runs a refrigerator, how long a power station runs a space heater, what size power bank for a Starlink Mini and how long a power station runs an electric blanket.
The formula
available Wh = rated Wh × (1 − reserve) watts from the battery = load watts ÷ efficiency × share of time on hours = available Wh ÷ watts from the battery
A power station is a battery, an inverter and a charger in one box, so the same arithmetic as a battery applies — with one simplification: its battery management already stops it before the cells are damaged, so you can use the rated watt-hours rather than a depth-of-discharge cut. What you lose is the conversion. Victron’s book puts good inverter efficiency above 90%, but the AC energy you actually get from a power station is usually lower once its own electronics and idle draw are counted, so the default here is a cautious 85%. If you have measured your unit, set your own figure.
Two ratings to check, not one
- Watt-hours decide how long. A 1,000 Wh station runs a 100 W AC load about 8.5 hours at 85%.
- Continuous and surge watts decide whether it runs at all. A fridge’s start surge (800–1,200 W on Champion’s chart for a household fridge) or a 1,500 W heater can trip an inverter that has plenty of watt-hours.
- Solar input watts decide how fast you get it back. A 1,000 Wh station on a 200 W panel needs several sunny hours to refill.
Typical loads
| Load | Typical watts | On a 1,000 Wh station (AC, 85%) |
|---|---|---|
| Starlink Mini (average) | 40 W | 21 h 15 min |
| CPAP, no heat | 60 W | 14 h 10 min |
| Electric blanket (double) | 100 W | 8 h 30 min |
| Box fan | 100 W | 8 h 30 min |
| TV, 55 in (ENERGY STAR certified) | 114 W | 7 h 27 min |
| Household fridge, running | 200 W | 4 h 15 min |
| Space heater, high | 1500 W | 34 min |
What you’ll need
- Portable power station (about 1,000 Wh)Premium price
Battery, inverter and charger in one box. Check both the watt-hour capacity and the inverter’s continuous and surge watts against what you plan to run.
See options on Amazon (opens in a new tab) - 100 W solar panelMid-range price
The building block of most van, boat and RV systems. Check the data-sheet Voc and Isc before you decide how to wire several of them.
See options on Amazon (opens in a new tab) - Inline DC watt meterBudget price
Sits between a 12 V device and its supply and shows watts, amps and watt-hours used — handy for measuring a 12 V fridge, Starlink Mini or fan.
See options on Amazon (opens in a new tab)
As an Amazon Associate we earn from qualifying purchases. Links to products are affiliate links — they cost you nothing extra and help keep these calculators free.
Frequently asked questions
How long will a 1000Wh power station run a fridge?
A household fridge drawing 200 W about a third of the time averages roughly 78 W from the battery at 85% efficiency, so about 12.9 hours. See how long a power station runs a refrigerator.
Why does my power station run out sooner than Wh ÷ watts?
The inverter loss (about 10%), the inverter’s idle draw, cold weather and the battery’s age all take a share. Watt-hours on the label are the battery’s, not what reaches your appliance.
Can a power station run a space heater?
Only a large one, and not for long: 1,500 W through the inverter drains a 1,000 Wh unit in about 34 minutes — if its inverter can carry 1,500 W at all. See how long a power station runs a space heater.
Is a power station a “solar generator”?
It is the same thing under a marketing name: a battery, inverter and charge controller in one box, charged from solar panels, a car or a wall outlet. It makes no power of its own.
Related guides
Sources
- Victron Energy — Energy Unlimited (book) (opens in a new tab) — Lead-acid charge efficiency 80–95% (85% suggested as a starting value); battery energy efficiency about 75% for full cycles, about 89% in partial state of charge; inverter efficiencies above 90%.
- Champion Power Equipment — Generator Wattage Chart (opens in a new tab) — Typical running and starting watts for household, RV and job-site appliances (a manufacturer’s planning chart — your nameplate wins).
- Virginia Cooperative Extension, BSE-301: Estimating Appliance and Home Electronic Energy Use (2020) (opens in a new tab) — Wattage × hours ÷ 1,000 = kWh per day; watts = amps × volts when only amps are listed; a refrigerator runs at full wattage about a third of the time; typical nameplate wattages.
- Starlink — Mini specification sheet (opens in a new tab) — Power consumption: average 25–40 W; input rating 12–48 V, 60 W.
- Starlink — Standard kit specification sheet (opens in a new tab) — Power consumption: average 75–100 W.