Critical-load planning

Backup power systems

Build from the load outward: identify critical circuits, starting surge, target runtime, transfer method, charging plan, and expansion path.

See best picks Compare products Calculate runtime

Decision chart Estimated runtime at a 150W critical-load bundle Starting estimate using 80% usable energy. Real runtime changes with surge, cycling, temperature, inverter draw, and battery condition.

300Wh battery 1.6 hr

500Wh battery 2.7 hr

1,000Wh battery 5.3 hr

2,000Wh battery 10.7 hr

3,600Wh battery 19.2 hr

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Most useful guides

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Recommended starting points

Products that fit this category

Use the linked guide and calculator to confirm the fit before buying.

Best all-around 1kWh pick

Power station · Best for Home outages, refrigerators, camping, and mixed loads

EcoFlow DELTA 2

1,024Wh 1,800W output LiFePO4

Check today’s Amazon price paid link Read the guide Official specifications ↗

Best expandable RV pick

Power station · Best for RVs, longer outages, higher-draw appliances, and expansion

Jackery Explorer 2000 Plus

2,042Wh 3,000W output LiFePO4

Check today’s Amazon price paid link Read the guide Official specifications ↗

Best heavy-load portable system

Power station · Best for Home backup, long outages, workshops, and large appliances

EcoFlow DELTA Pro

3,600Wh 3,600W output LiFePO4

Check today’s Amazon price paid link Read the guide Official specifications ↗

Two-minute sizing start

What are you trying to keep running?

Pick the load and target time. We will estimate the battery class, then send you to the right guide and full runtime calculator.