Wh vs W: what capacity and output ratings actually mean
Watt-hours (Wh) are how much energy the battery holds, so they decide runtime. Watts (W) are the most power the inverter can deliver at once, so they decide whether a device runs at all. Check watts first for heaters and motors, then Wh for how long.
Watt-hours (Wh) are the size of the tank: how much energy the battery holds, so they set how long a device runs. Watts (W) are the width of the pipe: the most power the inverter can deliver at once, so they decide whether a device runs at all. Two stations with the same Wh can behave very differently. The DJI Power 1000 Mini and the Anker SOLIX C1000 Gen 2 both hold about 1 kWh, but only one of them can run a 1,500 W space heater.
The two numbers on the spec sheet
Energy is power multiplied by time. A 1,500 W heater running for one hour uses 1,500 Wh, the same as a 15 W light running for 100 hours. Virginia Cooperative Extension uses the same arithmetic for household bills: wattage × hours ÷ 1,000 gives kilowatt-hours (Virginia Cooperative Extension (DOE figures)).
- Capacity (Wh or kWh) answers "for how long". Not all of it reaches your device: the calculator counts 90% as usable and loses more in the inverter (see the methodology).
- Continuous output (W) answers "can it run this". Go over it and the station shuts the outlet off, however full the battery is.
- Surge or peak (W) is a short burst above continuous, for motors that pull extra for a moment as they start.
- Boost modes such as EcoFlow X-Boost, BLUETTI Power Lifting or Anker SurgePad run heating devices above the continuous rating, but the makers' manuals say output stays at the rated level. The heater runs, but at less than its full power.
Worked example 1: same capacity, different output
Inputs: a portable space heater on high at 1,500 W (Virginia Cooperative Extension (DOE figures)). DJI lists the Power 1000 Mini at "1008 Wh" and "max 1000 W (continuous at 800 W)" (DJI spec page). Anker lists the C1000 Gen 2 with "2,000W output, 3,000W peak, and 1,024Wh capacity" (Anker SOLIX product page).
On the Power 1000 Mini, 1,500 W is above even its 1,000 W maximum, so the engine's verdict is "won't run": Draws 1,500 W; the Power 1000 Mini is rated 800 W continuous. It will shut off. On the C1000 Gen 2 the heater fits inside the 2,000 W rating, and capacity takes over:
| Usable energy | 1,024 Wh × 90% = 922 Wh |
|---|---|
| Pulled from the battery | 1,500 W ÷ 88% + 10 W idle = 1714.5 W |
| Runtime | 922 Wh ÷ 1714.5 W = 32 min |
32 min is the whole story for heat. A big inverter lets a 1 kWh station run a heater, but 1 kWh doesn't last long at 1,500 W.
Worked example 2: a small load, where output stops mattering
Inputs: a Starlink Mini at 33 W, inside the 25 to 40 W average on the Starlink Mini spec sheet, on the same two stations. Both outputs are far above 33 W, so only capacity counts.
| Usable energy | 1,008 Wh × 90% = 907 Wh |
|---|---|
| Pulled from the battery | 33 W ÷ 88% + 10 W idle = 47.5 W |
| Runtime | 907 Wh ÷ 47.5 W = 19 h 5 min |
The C1000 Gen 2 gives 19 h 24 min against the Power 1000 Mini's 19 h 5 min. The 1,200 W of extra output buys nothing here; the small gap comes from the 16 Wh difference in capacity.
Worked example 3: when boost mode makes the difference
The BLUETTI Elite 100 V2 is rated 1,800 W continuous with 2,700 W of Power Lifting (BLUETTI product page). The heater fits inside that continuous rating, so it runs at full power with no boost needed: about 32 min. The EcoFlow RIVER 2 Pro holds 768 Wh with only 800 W continuous, and its 1,600 W X-Boost ceiling just covers the heater, so it runs only in boost. X-Boost lowers the voltage instead of raising output, so the heater gets at most 800 W of heat, and the engine computes the runtime at that 800 W draw: about 45 min, not the 24 min a full 1,500 W would give. Treat boost as a way to get some heat, not full heat: a motor, pump or compressor gets no help from it.
Capacity and output side by side
Published capacity and output from each maker, with typical runtimes from the engine. A blank in boost means the maker lists no boost mode.
| Station | Capacity | Continuous | Boost or max | Space heater | Kettle | Starlink Mini |
|---|---|---|---|---|---|---|
| EcoFlow RIVER 2 Pro | 768 Wh | 800 W | 1,600 W | 45 min in X-Boost, runs at reduced power (at most 800 W of heat) | 45 min in X-Boost, runs at reduced power (at most 800 W of heat) | 14 h 33 min |
| BLUETTI Elite 100 V2 | 1,024 Wh | 1,800 W | 2,700 W | 32 min | 32 min | 19 h 24 min |
| DJI Power 1000 Mini | 1,008 Wh | 800 W | Won't run | Won't run | 19 h 5 min | |
| Jackery Explorer 1000 v2 | 1,070 Wh | 1,500 W | 33 min | 33 min | 20 h 16 min | |
| Anker SOLIX C1000 | 1,056 Wh | 1,800 W | 2,400 W | 33 min | 33 min | 20 h |
| Anker SOLIX C1000 Gen 2 | 1,024 Wh | 2,000 W | 32 min | 32 min | 19 h 24 min |
The Power 1000 Mini is compared against a 1,800 W station of the same size in Power 1000 Mini vs EcoFlow DELTA 3.
Common mistakes
- Reading Wh as a power limit. A 1,000 Wh station is not a 1,000 W station. Check the continuous output for anything that heats or has a motor.
- Adding up watts instead of watt-hours. Plugging in a 1,500 W kettle and a microwave at once needs the sum of both in watts. How long the battery lasts depends on how many hours each one runs.
- Dividing Wh by W and stopping there. 1,024 Wh ÷ 1,500 W suggests about 41 minutes for the heater, more than the engine gives, because the usable share and inverter loss come off first.
- Counting on boost for full power. Boost modes keep a heating load running by giving it less power, and they don't apply to motors.
- Paying for watts you won't use. For phones, laptops, routers and CPAPs, a bigger inverter adds weight and cost but no runtime. Spend on Wh instead.
Related power stations
Product images: official brand websites (Anker SOLIX, DJI, BLUETTI, EcoFlow).