Sizing your system starts with daily behavior, not product marketing. The right answer for a weekend camper is completely different from the right answer for a remote worker, and most buyers figure this out after they’ve already bought the wrong thing.
Track real device use first. Then choose capacity.
Why Raw Watt-Hours Mislead#
Marketing emphasizes total capacity. Real van life cares about usable capacity per day and how fast you get it back.
I can put hard numbers on that, because I’ve owned both sides of it.
I ran a Goal Zero Yeti 1400 from 2018 until November 2025. Its stock charger took roughly 25 hours to go wall-to-full. Spec I replaced it with a BLUETTI Elite 200 V2, which does about 1.5 hours on the same kind of outlet. Measured
Look at what actually changed between those two units:
| Yeti 1400 (2018) | Elite 200 V2 (2025) | Change | |
|---|---|---|---|
| Capacity | 1,425Wh | 2,073.6Wh | 1.5× more |
| Wall charge, empty to full | ~25 hours | ~1.5 hours | 17× faster |
The capacity barely moved. The recharge time collapsed. And the second number is the one that changed how the van feels to live in, not the first.
That’s the part the spec sheet buries. A big, slow battery and a smaller, fast one can carry the same day and still be completely different tools. If you’re parked somewhere with shore power every few nights, slow is survivable. If you’re moving daily and living off solar and the alternator, slow means you never fully recover, and every cloudy day digs the hole deeper.
Build Your Daily Load Estimate#
List everything you actually run and how long you run it. Don’t estimate from memory. Track a real day if you can.
Common van loads (Estimate):
| Device | Typical Draw | Hours/Day | Daily Wh |
|---|---|---|---|
| Laptop (15") | 45–65W | 6–8 | 270–520Wh |
| Mobile hotspot / router | 10–20W | 8–10 | 80–200Wh |
| LED lighting | 5–20W | 3–5 | 15–100Wh |
| Roof fan (mid-speed to wide open) | 15–32W | 6–8 | 90–256Wh |
| Phone charging | 10–18W | 2–3 | 20–54Wh |
| Coffee maker (travel) | 300–600W | 0.1 | 30–60Wh |
The fan figures are ours, measured rather than taken off a spec sheet. Add those up and a working day of devices lands between roughly 500 and 1,200Wh, depending on how hard the fan runs, how many hours you work, and whether you’re running a heater.
Then there’s the load that isn’t on that list.
The Fridge Is the Number That Breaks Most Estimates#
Every sizing guide I read before buying built its math out of laptops and phones. None of them led with the appliance that never turns off. A 12V compressor fridge runs around the clock, it runs hardest exactly when the weather is worst, and on most full-time builds it is the single largest line item in the day.
Here’s what mine actually pulls, measured over eight years on a Dometic CFX65DZ:
| Conditions | Average Draw | Hours/Day | Daily Wh |
|---|---|---|---|
| Florida summer, humid (Measured) | 20–25Wh/hr | 24 | 480–600Wh |
| Mild weather (Measured) | 10–12Wh/hr | 24 | 240–290Wh |
The compressor isn’t drawing that steadily. It cycles on and off at zero, and while it runs it pulls about 70W for the first minute of a cool-down before settling back. Measured The spec plate rates it at 5.5A at 12V, roughly 66W. Spec Averaged across an hour in real heat, it comes out to 20–25Wh consumed. Full breakdown in the fridge power draw post.
So the honest total for a full-timer with a fridge:
Devices (475–1,100Wh) + fridge (240–600Wh) = roughly 1,000–1,500Wh on a typical day, and up to 1,700Wh when a hot week and a heavy work week land together. Not 500Wh. If you size to a device-only estimate, you will be short every summer.
How I Actually Sized Mine, And What I Got Wrong#
I’d rather be honest about this than pretend I ran the math properly in 2018: I didn’t.
There weren’t many portable power stations worth buying back then. Goal Zero looked like the most reliable name and the best-built machine on a short list, so that’s what I bought. The decision was about brand and quality, not about a load calculation. If I had a daily number in my head at all it was something like 700Wh, and I genuinely don’t remember how I arrived at it.
The real answer, once a fridge ran around the clock through a Florida summer, was closer to double that.
Here’s the thing though: the Yeti was still a good purchase. It ran for seven years and it was a genuinely well-built machine. What I got wrong wasn’t the brand, it was the axis I was shopping on. I bought for capacity and reputation without ever asking how fast the thing came back up, and the recharge spec is the one that aged worst. It’s what turned every stacked-up bad week into a problem I had to drive around.
The market has also moved. You can now get roughly that same build quality for a lot less money, from several brands, with recharge times that make the 2018 units look like a different century. So do the sizing work I skipped, and weight recovery speed heavily when you compare.
Add Margin, Then Double-Check Recovery#
Once you have your daily estimate, don’t buy exactly that capacity. Add margin two ways:
Capacity margin: Buy 1.3–1.5× your daily estimate. This preserves battery health (shallower cycles extend usable life on LFP) and covers heavier days. A 1,200Wh daily estimate points toward a 1,600–1,800Wh station.
Recovery reality check: Can your charging sources recover that load in the time you have? This is where most buyers skip a step. A 1,000Wh station that only charges at 150W solar input needs nearly seven hours of full sun to refill. That doesn’t happen in most of the US outside of summer.
The Remote Worker Case#
Remote workers often assume they need massive capacity because laptops feel power-hungry. In practice, the load is manageable, but the recovery requirement is stricter than expected.
Running a laptop and hotspot eight hours a day is roughly 400–600Wh. On its own that’s easy. Put a fridge underneath it and the same day becomes 900–1,200Wh, which is where a lot of first builds come up short. The harder problem is that you need the station substantially recharged by the next morning, every morning.
That makes charge rate the deciding factor, not total Wh. A 1,000Wh station that charges at 800W AC and 300W solar is more useful for daily remote work than a 2,000Wh station that charges at 100W solar only. The big one looks safer on the box and then never comes back up after a cloudy day.
Where Most Buyers Go Wrong#
Chasing maximum Wh. Bigger sounds safer. But a large, slow-charging station leaves you anxious every cloudy day and every extended stay without power access.
Ignoring realistic solar harvest. A panel rated at 200W doesn’t deliver 200W except in ideal conditions. Panels you can angle and keep clean land around 75–90% of nameplate. Panels bolted flat to a van roof, which is nearly all of us, give up another chunk to the fixed angle: I plan mine at 60–75% of rated, and less in partial shade or overcast. If solar is your primary source, size input capacity accordingly. Full breakdown of the derate here.
Forgetting the heat and HVAC wildcard. If you’re running a 12V fan most of the night in summer, that adds 100–200Wh to your daily total quietly, and considerably more if you’re running it on high. Do the math with the fan on.
Quick Sizing Targets (Estimate)#
Two load columns, because whether you run a fridge changes the answer more than anything else on this page.
| Van Use Pattern | Devices Only | With a 12V Fridge | Suggested Station Size |
|---|---|---|---|
| Weekender, minimal devices | 150–300Wh | 400–900Wh | 700–1,200Wh |
| Part-time remote work | 400–600Wh | 650–1,200Wh | 1,000–1,500Wh |
| Full-time remote work | 600–900Wh | 850–1,500Wh | 1,200–2,000Wh |
| Heavy use (CPAP + work + cooking) | 900–1,400Wh | 1,150–2,000Wh | 2,000–3,000Wh |
Station sizes come from the with-fridge column at the 1.3–1.5× margin above. If you’re genuinely fridge-free, size off the middle column instead and you’ll save real money.
These are planning ranges, not guarantees. Your actual load depends on your specific devices, climate, and habits.
The Week That Set These Numbers#
Summer 2019, Santa Rosa Beach on the Florida panhandle. Seven straight days of overcast. Heat and humidity the whole time, so the fridge never stopped cycling and the fans never stopped running, and the panels gave us close to nothing for a week.
We hauled the Yeti into coffee shops nearly every day that week. Two hours plugged in got us about 8% back. The math never caught up.
What that week taught me is the order things fail in, and it isn’t the order you’d guess. Comfort goes first. You sweat. You stop running the fans. You sit still and you stop doing the things you moved into a van to do. The one load you cannot let fail is the fridge, because losing the food costs more than being miserable does.
That’s why I don’t think of capacity as a comfort number anymore. It’s the buffer between a bad weather week and a week where you’re rationing. Size the tank for your real load, fridge included, then make sure you can actually refill it before the next morning. Get the second part wrong and the first part won’t save you.