A backup battery (or high-capacity power station) takes over during an outage: it powers your fridge, router, lights and medical devices. Here is how to size it, plus our selection.
How to choose
- Capacity and expandability: 3,000 Wh covers the essentials; choose expandable models to last several days.
- Continuous power (W): 3,000 W+ to run several appliances, even a space heater.
- Switchover time (UPS): under 20 ms protects computers and routers without interruption.
- Solar input: to extend runtime during long outages.
Our top picks
EcoFlow Delta Pro 3
Key specs : 4096 Wh · 4000 W · LiFePO4 · 3199 €
The backup benchmark: 4,096 Wh, 4,000 W and expandable, with UPS function to switch over instantly during an outage.
Bluetti AC300 + B300
Key specs : 3072 Wh (extensible 12 288 Wh) · 3000 W · 2999 €
Modular system: 3,072 Wh expandable to 12,288 Wh, 3,000 W; you match capacity to your needs.
Anker SOLIX F3800
Key specs : 3840 Wh (extensible 26 880 Wh) · 6000 W · 3599 €
Power and big reserve: 3,840 Wh expandable, 6,000 W, able to run demanding appliances (hotplate, tools).
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FAQ
What capacity to ride out an outage?
For the essentials (fridge, router, lights) over 24 h, plan 2,000 to 3,000 Wh; double it or add solar for several days.
Can it power the whole house?
Expandable models with a transfer panel can power entire circuits; otherwise plug priority appliances directly.