Capacity Guide
Watt-hours explained. Capacity tiers from 500Wh to 4,000Wh+. Appliance wattage tables and medical equipment sizing.
A watt-hour (Wh) is a unit of energy. It's the amount of power (watts) used over time (hours). Think of it like a gas tank: the Wh number tells you how much energy the station can store.
🔋 Simple formula: Watts × Hours = Watt-Hours
A 100W light bulb running for 10 hours uses 1,000Wh (100W × 10h = 1,000Wh).
Why this matters: A power station's Wh rating determines how long it can run your devices. A 1,000Wh station can run a 100W device for 10 hours, or a 500W device for 2 hours.
Reality check — the 85% rule: In real-world use, you lose about 15% to inverter inefficiency. A 1,000Wh station realistically delivers ~850 usable Wh. Always size 15–20% larger than your calculated needs.
New to portable power? Start with the beginner's guide.
What is a Portable Power Station? →Ready to size your system precisely?
Power Calculator →📱 Entry (500–1,000Wh)
Phone, laptop, lights, small fan. 1–2 nights of basic needs. Best for weekend camping and emergency phone backup.
Examples: Bluetti EB3A (268Wh), Jackery Explorer 500 (518Wh), EcoFlow River 3 (245Wh)
🏕️ Mid (1,000–2,000Wh)
CPAP (1–2 nights), mini-fridge (12–24h), TV, multiple laptops. Best for CPAP users and van life weekends.
Examples: EcoFlow Delta 3 Plus (1,024Wh), Anker SOLIX C1000 Gen 2 (1,056Wh)
🏠 Large (2,000–4,000Wh)
CPAP (4–7 nights), full-size fridge (12–24h), medical devices, home backup. Best for full-time van life and home backup.
Examples: EcoFlow Delta 3 Max Plus (2,048Wh), Jackery Explorer 2000 Plus (2,042Wh), Bluetti Elite 300 (3,014Wh)
⚡ Whole-Home (4,000Wh+)
Oxygen concentrator, ventilator, whole-house circuits, extended outages. Best for critical medical and off-grid living.
Examples: EcoFlow Delta Pro 3 (4,096Wh), Anker SOLIX F3800 (3,840Wh), Jackery HomePower 3600 Plus (3,584Wh)
⚠️ The 3-day rule: If you're buying for emergency backup, size for 3 days without recharging. A CPAP user needs ~360Wh/night → 1,080Wh for 3 nights → buy 1,500Wh+.
See all four brands compared by capacity tier
Big 4 comparison →| Device | Typical Watts | Daily Wh (8–24h use) | 1,000Wh Runtime |
|---|---|---|---|
| 💡 LED Light Bulb | 5–10W | 40–80Wh | 100–200 hours |
| 📱 Phone Charger | 5–20W | 20–40Wh | 50–200 charges |
| 💻 Laptop | 30–65W | 240–520Wh (8h) | 15–33 hours |
| 📡 Starlink Mini | 20–40W | 160–320Wh (8h) | 25–50 hours |
| ❄️ Mini Fridge (12V) | 45–60W avg | 500–800Wh | 20–24 hours |
| ❄️ Full-Size Fridge | 100–200W avg | 1,000–2,000Wh | 5–10 hours |
| 😴 CPAP (no humidifier) | 45W | 360Wh (8h) | 2.7 nights |
| 😴 CPAP (with humidifier) | 80–100W | 640–800Wh (8h) | 1.3–1.6 nights |
| 🩸 Oxygen Concentrator (3LPM) | 300W | 7,200Wh (24h) | 3.3 hours |
| 💨 Ventilator | 200W | 4,800Wh (24h) | 5 hours |
| ❄️ Insulin Fridge (12V medical) | 45W | 1,080Wh | 22 hours |
| 🎥 TV (50-inch) | 60–100W | 240–400Wh (4h) | 10–16 hours |
| 📶 WiFi Router | 5–15W | 120–360Wh | 66–200 hours |
| ♿ Power Wheelchair Charger | 200W | 1,600Wh (per charge) | 5 hours (1 charge) |
💡 Pro tip: Add up the daily Wh of everything you'll run. Multiply by 1.15 for inverter loss. Then add 20% buffer. That's your minimum station capacity.
⚠️ Medical devices require special consideration: UPS pass-through (0–30ms switchover), pure sine wave output, and 20–30% extra capacity buffer. Never size exactly — always oversize for medical applications.
| Device | Watts | Wh per day | Minimum Station | Recommended |
|---|---|---|---|---|
| CPAP (no humidifier) | 45W | 360Wh | 1,000Wh | 2,000Wh+ |
| CPAP (with humidifier) | 90W | 720Wh | 2,000Wh | 3,000Wh+ |
| Oxygen (3 LPM) | 300W | 7,200Wh | 6,000Wh | 10,000Wh+ expandable |
| Ventilator | 200W | 4,800Wh | 4,000Wh | 8,000Wh+ expandable |
| Insulin Fridge (12V) | 45W | 1,080Wh | 1,500Wh | 2,000Wh+ |
Complete medical backup plan — station picks, UPS explained, CPAP runtimes
Medical Backup Guide →Why UPS switchover speed matters for medical devices
UPS Guide →How long will a station run your devices?
Want to size a full system including solar?
Power Calculator →Runtime by Device (1,000Wh station)
Daily Wh by Use Case
Station Capacity Tiers
Medical Device Daily Wh
See how brands compare at each capacity tier
Battle pages →