The most common confusion when buying portable power stations is understanding the difference between battery capacity (Wh) and output power (W). These two specifications serve completely different purposes, and choosing the wrong combination leads to disappointment and wasted money.
The Two Critical Specifications
Battery Capacity (Wh - Watt-Hours)
What it means: How much total energy is stored in the battery.
What it determines: How long the power station can run your devices.
The analogy: Think of capacity like a fuel tank in a car - larger tanks let you drive further.
Output Power (W - Watts)
What it means: How much power the power station can deliver at any given moment.
What it determines: What devices you can run and how many simultaneously.
The analogy: Think of output like engine horsepower - more powerful engines can pull heavier loads.
A Real-World Example
Consider two very different power stations:
Option A: Jackery Explorer 3000V2
- Capacity: 3072Wh
- Output: 2990W (6000W surge)
- Price: £2319
- Weight: 27kg
Option B: EcoFlow RIVER 2 Pro
- Capacity: 768Wh
- Output: 800W (1600W surge)
- Price: £349
- Weight: 7.8kg
The Jackery has 4x the capacity and nearly 4x the output. But does that mean it's 4x better? Not necessarily - it depends entirely on your use case.
Scenario 1: Charging a 50W Laptop
Jackery 3000V2: 3072Wh ÷ 50W = 61 hours of runtime
EcoFlow RIVER 2 Pro: 768Wh ÷ 50W = 15 hours of runtime
Both can easily power the laptop (only 50W output needed). The Jackery lasts longer, but 15 hours is plenty for most camping trips. The RIVER 2 Pro weighs 19kg less and costs £1970 less.
Scenario 2: Running a 1500W Electric Heater
Jackery 3000V2: Can run it (2990W output). Runtime: 3072Wh ÷ 1500W = 2 hours
EcoFlow RIVER 2 Pro: Cannot run it (only 800W output available)
Here, the Jackery is essential - not because of capacity, but because of output power. The RIVER 2 Pro physically cannot deliver 1500W, regardless of having a full battery.
Calculating Runtime for Your Devices
Use this simple formula:
Runtime (hours) = Battery Capacity (Wh) ÷ Device Power Consumption (W) × 0.85
The 0.85 factor accounts for inverter efficiency (AC power requires conversion, losing ~15%).
Common Device Power Consumption
| Device | Typical Power Draw | Runtime on 768Wh Unit | Runtime on 3072Wh Unit |
|---|---|---|---|
| Smartphone charging | 10-18W | 40-65 hours | 160-260 hours |
| Laptop | 45-90W | 7-14 hours | 29-58 hours |
| Mini fridge (12V) | 40-60W | 11-16 hours | 43-65 hours |
| LED camping light | 5-15W | 43-130 hours | 173-520 hours |
| CPAP machine | 30-60W | 11-22 hours | 43-87 hours |
| Electric kettle | 1000-1500W | 30-45 minutes | 2-3 hours |
| Hair dryer | 1200-1800W | 25-38 minutes | 1.7-2.5 hours |
| Microwave (small) | 600-900W | 50-77 minutes | 3-5 hours |
Matching Capacity to Your Needs
Small Capacity (250-500Wh) - "The Essentials"
Best for: Phone charging, tablets, small devices, emergency backup
Not suitable for: Appliances, power tools, running refrigerators
Example: VTOMAN Jump 600X (299Wh, £189)
- Charge iPhone 15-20 times
- Run laptop for 5-6 hours
- Power LED lights for 40+ hours
- Perfect for day trips and emergency charging
Medium Capacity (500-1000Wh) - "The Sweet Spot"
Best for: Weekend camping, multi-device charging, small appliances, CPAP users
Can handle: Mini-fridges, small power tools, multiple devices simultaneously
Example: Anker SOLIX C800 (768Wh, £599)
- Run camping fridge all weekend
- Charge phones and laptops multiple times
- Power CPAP for 2-3 nights
- Ideal for serious campers and weekend warriors
Large Capacity (1000-2000Wh) - "The Extended Stay"
Best for: Extended camping, van life, remote work, multi-day power needs
Can handle: Extended appliance runtime, multiple devices for days
Example: Anker SOLIX C1000 (1056Wh, £999)
- Week-long camping trips
- Running mini-fridge 24/7 for days
- Full remote work setup for multiple days
- Serious off-grid capabilities
Extra Large Capacity (3000Wh+) - "The Home Backup"
Best for: Home emergency backup, construction sites, professional use, RV living
Can handle: Full-size refrigerators, multiple appliances, whole-home essentials
Example: EcoFlow DELTA Pro 3 (4096Wh, £3299)
- Run refrigerator for 2-3 days during outages
- Power home office equipment for extended periods
- Construction site power for full workday
- Expandable capacity for even longer runtime
Understanding Output Power Needs
Low Power (300-600W) - Basic Devices
Sufficient for:
- Phones, tablets, laptops
- LED lights and fans
- Small electronics
- CPAP machines
Example: EcoFlow Trail 300 DC (300W output, £169)
Medium Power (700-1200W) - Most Appliances
Sufficient for:
- Everything above, plus:
- Small microwaves
- Coffee makers
- Mini-fridges and coolers
- Most power tools
Example: BLUETTI AC50B (700W output, £249)
High Power (1800-3000W) - Heavy Appliances
Sufficient for:
- Everything above, plus:
- Electric kettles
- Hair dryers
- Space heaters
- Power-hungry tools
Example: Bluetti APEX 300 (3000W output, £2999)
Very High Power (3600W+) - Professional Grade
Sufficient for:
- Everything above, plus:
- Air conditioners
- Full-size refrigerators
- Welding equipment
- Industrial tools
Example: VTOMAN FlashSpeed Pro 3600 (3600W output, £1399.99)
The Surge Power Factor
Many appliances need 2-3x their running power when starting. This is called "surge" or "peak" power. Motors and compressors are the main culprits:
- Refrigerators: Run at 100-200W, start at 600-1200W
- Air conditioners: Run at 1000-1500W, start at 3000-4500W
- Circular saws: Run at 1200W, start at 2400W
Always check the surge rating. The Anker SOLIX F3800 offers 6000W continuous with 9000W surge - enough to start virtually any household appliance.
Common Mistakes to Avoid
Mistake #1: Buying Too Much Capacity, Not Enough Output
❌ "I bought a 2000Wh unit but it can't run my 1500W heater because it only has 1000W output."
✓ Check output power matches your highest-wattage device.
Mistake #2: Buying Too Much Output, Not Enough Capacity
❌ "My 3000W power station runs my coffee maker, but the battery dies after 3 uses because it only has 500Wh."
✓ Calculate runtime requirements for realistic expectations.
Mistake #3: Ignoring Surge Requirements
❌ "My fridge needs 150W and my power station has 500W, but it won't start."
✓ The fridge likely needs 600-900W surge power. Check surge ratings.
Mistake #4: Not Accounting for Inverter Efficiency
❌ "My 1000Wh battery should run my 100W device for 10 hours, but it only lasted 8."
✓ AC power requires DC-to-AC conversion, losing 10-15% efficiency. Use the 0.85 multiplier in calculations.
Finding Your Perfect Match
Answer these questions:
- What's my highest-wattage device? Your output needs.
- How long do I need to run devices? Your capacity needs.
- Do I have motor-driven appliances? Check surge requirements.
- What's my budget? Balance capacity/output with cost.
Budget-Conscious Picks
- £159: Jackery Explorer 240 v2 - 256Wh, 300W - Perfect starter unit
- £349: EcoFlow RIVER 2 Pro - 768Wh, 800W - Best value mid-range
- £1399: VTOMAN FlashSpeed Pro 3600 - 3096Wh, 3600W - Incredible power-to-price
Premium Performance
- Compact champion: Anker SOLIX C1000 - 1056Wh, 1800W - £999
- Home backup king: Anker SOLIX F3800 - 3840Wh, 6000W - £2599
- Fast charging master: EcoFlow DELTA Pro 3 - 4096Wh, 4000W - £3299
Use our comparison tool to filter by capacity, output, and price: Compare all power stations