Watts vs. Watt-Hours
Watts are inverter output. Watt-hours are battery size. You need both.
People mix these up on spec sheets. Watts are how hard the station can push. Watt-hours are how long it can last.
Think of a car: watts are horsepower, watt-hours are the fuel tank.
Watts (inverter)
This is the AC output rating. It decides what you can run right now.
- Running watts: continuous output
- Surge watts: a short spike to start motors (fridges, pumps, tools)
If startup draw is higher than surge rating, the station will refuse or trip. Many motor loads want 2–3× running watts at start.
Watt-hours (battery)
This is stored energy. A 1000 Wh pack running a 100 W TV is about 10 hours in theory (closer to 8–9 hours after inverter loss). Higher draw empties the pack faster. Bigger packs cost more and weigh more.
You need both
- High watts, small battery: can start a microwave, may not run it long
- Large battery, low watts: can keep a fridge going, may not start a saw
| Job | Watts | Watt-hours |
|---|---|---|
| Microwave | 1000W+ surge | 1000Wh+ for ~30 min |
| Fridge overnight | ~200W continuous | 2000Wh+ for 24 h |
| Laptops and phones | ~100W total | 500Wh+ for a weekend |
| CPAP overnight | ~50W continuous | 400Wh+ for 8 h |
Use the sizing guide for watt-hours, then check surge on the same listing.