RV & Vanlife Power Sizing: How Many Watt-Hours Do You Actually Need? (2026)
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“How many watt-hours do I need?” is the most-asked question in vanlife power, and the answer is refreshingly calculable: list your devices, multiply watts × hours, add 20% headroom. Here’s the math for the three most common setups.
The 80/20 of RV loads
| Device | Typical draw | Typical use | Wh/day |
|---|---|---|---|
| 12V compressor fridge | 45W | 24h (cycles ~50%) | ~540 |
| LED lights | 20W | 5h | 100 |
| Laptop | 65W | 4h | 260 |
| Phones + USB bits | 20W | 3h | 60 |
| Roof vent fan | 30W | 8h | 240 |
| Starlink dish | 75W | 6h | 450 |
| Microwave | 1000W | 15 min | 250 |
| Induction cooktop | 1500W | 30 min | 750 |
| Electric kettle | 1200W | 12 min | 240 |
The fridge is the baseline everything else stacks on. Starlink surprises people — 75W × 6 hours is 450Wh, nearly a fridge by itself.
fridge 150W × 10h ≈ 1500Wh
microwave needs 1000W+ sustained
neither wasted
Our RV sizer does this math for you — see the tools page.
Three setups, three answers
Weekend warrior (fridge, lights, laptop, phones): ~1,000Wh/day. A 1kWh station like the Anker SOLIX C1000 covers a full day; recharge while driving home.
Full-time vanlife (add Starlink, fan, some cooking): ~2,500–3,500Wh/day. You want 2kWh minimum — the Anker C2000 Gen 2 or EcoFlow DELTA 2 Max — plus 400–800W of solar to break even on sunny days.
Off-grid with cooking (induction + kettle + microwave): 4,000–5,000Wh/day. Now you’re in 3kWh territory (Anker F3000) with serious solar, or an expandable flagship.
The AC question
Rooftop air conditioning is the load that breaks portable math: ~1,500W running, 3,000W+ starting, for 8 hours overnight = 12kWh. No portable station does that alone. If AC is non-negotiable, you’re looking at a soft-start capacitor + the biggest station you can afford for a few hours of pre-cooling — or a generator.
Don’t guess — calculate
Loads vary wildly by fridge size, climate and habits. Our RV power sizer lets you check off your actual devices and get matched stations in about 30 seconds.
Recharging on the road: the three speeds
Slow (free): 12V car outlet, ~100W. Fine for topping up a 1kWh station over a long driving day. Useless for 2kWh+ — the math doesn’t work.
Fast (installed): DC-DC alternator charger, 500–800W. The vanlife standard: charges while you drive, a 2kWh station refills in 3–4 hours of highway time. Needs wiring and usually a professional install, but it’s the closest thing to “free energy” that exists.
Free (parked): solar, 200–1200W depending on roof. The only recharge that works when you’re stationary for days. Size it with our solar pairing guide — and remember panels make ~75% of label in real conditions.
Most experienced vanlifers run alternator + solar together: drive-days refill the battery, solar stretches it between drives.
Cold weather derating
LiFePO4 batteries don’t like charging below freezing (32°F/0°C) — good stations refuse or heat first, cheap ones degrade. In winter: keep the station inside the heated living space, not an uninsulated garage bay; expect 10–20% less usable capacity in the cold; and don’t leave it at 100% for weeks unused — 50–80% is the happy storage zone. If you winter camp regularly, this matters more than brand choice. For the general sizing method behind all these numbers, see what size power station you need.