Two numbers on a power station's spec sheet cause most of the confusion: capacity in watt-hours (Wh) and output in watts (W). Here, 2,764.8Wh is how much energy is stored, and 3,840W is how fast that energy can be delivered. This guide explains what each number means, how surge watts fit in, and how to work out what you can run. Specs vary by model and firmware, so confirm current figures on the official Bluetti site before buying.
Capacity vs. output: the tank and the hose
Think of capacity as the size of a fuel tank and output as how wide the hose is. A big tank with a narrow hose runs small things for a long time. A wide hose on a small tank runs big things, but only briefly.
- Capacity (Wh): 2,764.8Wh means the battery can deliver roughly 2,764.8 watts for one hour, or 276 watts for ten hours, before conversion losses.
- AC output (W): 3,840W is the most the inverter should supply continuously across everything plugged in.
- Surge (W): a short-lived higher limit that covers motor start-up. Check the spec sheet for the exact figure and duration for your model.
Real runtime: why the math is never perfect
Converting battery power to AC wastes some energy as heat, and the inverter uses a little power even when idle. A common planning assumption is to expect 80–90% of rated capacity as usable AC energy. Treat that as a rule of thumb, not a guarantee.
Quick formula: usable Wh ≈ capacity × 0.85. For 2,764.8Wh, that is about 2,350Wh. Divide by your load in watts to estimate hours.
What can it run? Example estimates
Wattages below are typical ranges, not measurements of specific products. Check the label on your own appliance.
| Appliance | Typical running watts | Rough runtime on ~2,350Wh |
|---|---|---|
| Wi-Fi router and modem | 15–30W | 80+ hours |
| LED lighting (a few rooms) | 30–60W | 40–80 hours |
| Modern refrigerator (averaged over cycling) | 50–150W | Around 1–2 days |
| Laptop and monitor | 60–120W | 20–40 hours |
| Microwave | 1,000–1,500W | About 1.5–2 hours of cooking |
| Space heater | Up to 1,500W | Under 2 hours |
The pattern is clear: electronics and refrigeration are easy, while anything that makes heat drains the battery quickly.
Surge watts and motor loads
Refrigerators, well pumps, sump pumps, compressors and power tools draw several times their running wattage for a moment at start-up. If the surge exceeds the inverter's limit, it may shut down or trip. To plan:
- Find the running watts and, if listed, the starting or locked-rotor amps on the appliance label.
- Multiply amps by volts to estimate start-up watts.
- Start the biggest motor first, then add other loads.
- Keep total running load comfortably under the continuous rating, leaving headroom.
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A 3,840W rating does not automatically mean every appliance will work. Some large items, such as certain dryers, ranges or well pumps, need 240V. See Bluetti 120V vs 240V Output: Which Appliances Need Split-Phase Power and Who Needs It before assuming a big load will run. Connecting a unit to a home panel is electrical work, so use a licensed electrician and follow local codes.
Trade-offs to be honest about
- High output drains fast. Running near 3,840W empties the battery in well under an hour.
- Capacity can be expanded, output usually cannot. Extra batteries add hours, not watts. See Bluetti Expansion Batteries Compared: B300K vs B500K and Which to Add.
- Power Lifting mode may help with some resistive loads that exceed rated output, but it has limits. Read What is Bluetti Power Lifting mode and when should you use it?
- Recharge time matters. A large battery is only useful if you can refill it. See How to Charge a Bluetti Power Station and the solar generator guide.
- Chemistry affects lifespan. See LiFePO4 Batteries in Bluetti Power Stations.
A simple sizing method
- List the devices you need during an outage.
- Write down each one's running watts and estimate daily hours of use.
- Multiply watts by hours to get Wh per device, then add them up.
- Check that the largest simultaneous load, plus start-up surge, fits the inverter limits.
- Compare your daily Wh with about 85% of capacity, and decide how you will recharge.
Related questions
- Can you use a Bluetti while it is charging (pass-through power)?
- Can you leave a Bluetti plugged in all the time?
- Can you charge a Bluetti from your car with the Charger 2?
- What does the Bluetti Hub A1 do and do you need one?
Next steps
For a broader look at batteries, ports and add-ons, read What's Inside a Bluetti: Specs, Batteries and Add-Ons Explained. Once you know your daily watt-hours and peak load, compare models in our review and comparison pages, and confirm current specs, bundles and pricing on the official Bluetti site. For day-to-day care, see How to Use and Store a Bluetti.
Safety note: do not use power stations for life-support or medical equipment without guidance from the device maker and a medical professional.
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