How long will the EcoFlow DELTA Pro 3 run a box fan?

About 41 hours from a full charge. A box fan averages about 85 W, and the 4,096 Wh battery gives about 3,482 Wh after inverter losses. That is 2.4% of the battery an hour.

Can I run other things at the same time?

Yes, up to about 3,915 W more of the 4,000 W output. Each thing you add shares the same battery, so the 41 hours for a box fan gets shorter.

How many days of normal use is that?

About 5 days, if you use a box fan about 8 hours a day and nothing else is plugged in.

EcoFlow · Will it run?

Can the EcoFlow DELTA Pro 3 run a box fan (20 in)?

Published October 16, 2026

Short answerYes

Yes. The EcoFlow DELTA Pro 3 runs a box fan for about 41 hours from a full charge. At about 85 W on average it uses 2.4% of the battery an hour, and the 4,000 W output leaves plenty of room for more.

Add your other devices

Key numbers

Runtime: 41 hrs; from a full charge
Battery used per hour: 2.4%; at 85 W average

Box fan (20 in)

Running: 85 W; 56–200 W range
Start-up: 102 W
Average: 85 W; runs all the time

EcoFlow DELTA Pro 3

Battery: 4,096 Wh; about 3,482 Wh usable
Output: 4,000 W; continuous
Surge: 8,000 W; start-up peak

How we worked it out: 4,096 Wh × 0.85 ÷ 85 W = about 41 hours. The 0.85 covers inverter and battery losses. We do not test units ourselves; the numbers come from the official spec sheets and typical device draws. How we pick

EcoFlow DELTA Pro 3

4,096 Wh · 4,000 W output · 8,000 W surge · 113.5 lb

Full specs and runtimes

Check price on Amazon Check price at EcoFlow

We may earn a commission if you buy through these links. It doesn’t change your price. How we make money

What else the EcoFlow DELTA Pro 3 runs

One device at a time, from a full charge.

Other power stations for a box fan

The nearest sizes that also run it.

Keep going

Real runtime depends on the model you own, room temperature and battery age. The 41 hours above is an estimate, not a measured result.

Common questions

How long will the EcoFlow DELTA Pro 3 run a box fan?: About 41 hours from a full charge. A box fan averages about 85 W, and the 4,096 Wh battery gives about 3,482 Wh after inverter losses. That is 2.4% of the battery an hour.
Can I run other things at the same time?: Yes, up to about 3,915 W more of the 4,000 W output. Each thing you add shares the same battery, so the 41 hours for a box fan gets shorter.
How many days of normal use is that?: About 5 days, if you use a box fan about 8 hours a day and nothing else is plugged in.