Battery backup for power outages: what you can realistically run
A portable power station won't run your whole house, but it can keep the fridge cold, the Wi-Fi up, the lights on and medical devices running, silently and indoors. Here's how to plan it.
Three levels of home backup
| Level | What it covers | Typical size | Connection |
|---|---|---|---|
| 1. Essentials | Phones, router, lights, CPAP, laptop | 500–1,500 Wh, 1,000 W+ | Plug devices in directly |
| 2. Kitchen & comfort | Add the fridge or freezer, TV, fans, occasional microwave | 2,000–4,000 Wh, 2,000 W+ with surge | Heavy-duty extension cords |
| 3. Home circuits | Selected circuits, well or sump pump, 240 V loads | 3,000 Wh+ expandable, 3,500 W+, 240 V | Transfer switch or interlock, installed by a licensed electrician |
Whole-home battery systems that run central AC and electric ranges are a different category: wall-mounted batteries wired into the panel, usually 10–30 kWh and paired with rooftop solar. Expect a professional installation and a much higher budget.
How long will a power station last in an outage?
Rough runtimes at 85% usable energy. Fridge figures assume a modern full-size fridge averaging about 60 W across its on/off cycle.
| Load | Average draw | 1,000 Wh | 2,000 Wh | 3,800 Wh |
|---|---|---|---|---|
| Router + modem | 20 W | ≈42 h | ≈85 h | ≈160 h |
| CPAP (no humidifier) | 40 W | ≈21 h (2+ nights) | ≈42 h | ≈80 h |
| Refrigerator | ≈60 W avg | ≈14 h | ≈28 h | ≈54 h |
| Fridge + router + lights | ≈90 W avg | ≈9 h | ≈19 h | ≈36 h |
| Window AC (5,000 BTU) | ≈270 W avg | ≈3 h | ≈6 h | ≈12 h |
| Space heater (low) | 750 W | ≈1 h | ≈2.3 h | ≈4.3 h |
Heating and cooling are where batteries run out fastest. For long winter outages, plan to keep warm without electric heat.
Extension cords vs a transfer switch
Extension cords are the simple, safe default: run a properly rated cord (12 or 14 gauge for fridge-size loads) from the station to each appliance. No electrician needed.
A transfer switch or generator interlock lets a large station feed selected household circuits, so you can run hardwired items like a furnace blower or well pump. It must be installed by a licensed electrician to meet code and keep utility workers safe.
Battery power station vs gas generator
| Battery power station | Gas / propane generator | |
|---|---|---|
| Indoor use | Yes, no exhaust | Never: carbon monoxide risk |
| Noise | Near silent (fans only) | Loud (typically 50–75 dB) |
| Runtime | Limited by battery; extend with solar | As long as you have fuel |
| Upfront cost per usable kWh | Higher | Lower |
| Maintenance | Minimal; keep charged | Oil, fuel stabilizer, regular test runs |
| Best for | Short and medium outages, apartments, medical devices | Long outages, high-wattage loads |
Many households combine the two: a battery for quiet overnight power and medical devices, plus a generator run outdoors during the day to recharge it.
Outage-readiness checklist
- Write down the watts of the devices you'd actually keep running. Our calculator takes about two minutes.
- Keep the station at 60–80% charge in storage and top it up every 3 months (check the manual).
- Store the right cables: heavy-duty extension cords, the CPAP DC cable, solar adapter cables.
- Do a dry run: unplug the fridge from the wall, plug it into the station for an hour, and watch the readout.
- Have non-electric backups for heat, light and cooking.
Size your outage backup
Start with the "Storm prep" or "Power outage essentials" scenario and adjust.