Powerstation for your motorhome: how to calculate the right capacity

The cool box is running, the laptop's plugged in charging, and the lights stay on until midnight. By day three off-grid, the powerstation is empty. Once you've cut it too close, you stop buying by gut feeling.

So before you buy, it's worth doing the math honestly. Not every use case justifies a big powerstation – more on that later. First, let's get the number right.

Watts, watt-hours, and what's actually on the label

The figure on the label is usually the rated or maximum output. Devices like cool boxes cycle on and off, so they don't run at full power the whole time. Actual consumption is often lower.

Some devices briefly draw much more when switching on. The most accurate way to know is to measure it yourself: with a plug-in power meter at home, or via your powerstation's display or app.

Sample calculation for a typical motorhome

Here's how a realistic daily consumption adds up:

The cool box is the biggest consumer by far. How much it actually needs depends heavily on outside temperature, insulation, and the set temperature. On hot days, the compressor kicks in more often, and you can easily hit 400 Wh or more. Many compressor cool boxes list consumption per 24 hours in the spec sheet – that's far more useful for planning than the raw wattage.

An absorber cool box doesn't belong on a powerstation. At 2,400 to 3,600 Wh per day, it needs several times as much power and will drain even a large unit in under a day.

And 540 Wh is really the frugal scenario. Add an evening TV, a second laptop, or a heater fan, and you're quickly at 900 to 1,000 Wh per day.

From daily consumption to the right capacity

The watt-hours printed on the box don't all reach your devices. Converting voltage costs energy along the way. Plan on around 85 to 90 percent usable capacity on the 230-volt side. Then add some buffer for hot days, battery aging, and the unexpected – about 20%. Combined with the 10% conversion loss, that's roughly 30% more capacity than you actually use:

Required capacity = daily consumption × 1.3 × days off-grid

For our example of 540 Wh and two days without recharging, that means:

540 Wh x 1.3 × 2 ≈ 1,404 Wh

So a 1,000 Wh powerstation gets you comfortably through one day. If you want to go two days off-grid, aim for something closer to 1,500 to 2,000 Wh.

You don't need to factor in depth of discharge separately with a powerstation. The built-in battery management already protects the cell from being drained too deep.

Hidden losses: inverters and charging paths

As soon as you use the powerstation's 230-volt outlet, the inverter kicks in. It converts battery voltage into mains voltage, and that costs energy. Charging your phone through a regular 230-volt charger uses 20 to 30 percent more energy than charging it directly via USB. On top of that, there's standby drain: a switched-on inverter draws power even with nothing plugged in. Depending on the device, that's a few watts – but over 24 hours, it adds up.

So the rule of thumb is:

• Charge phones, tablets, and laptops via USB-C, not through the 230-volt charger. For laptops, you'll normally need a USB-C port with PD (Power Delivery) – it's always labeled as such.

• Run 12-volt devices like the cool box directly off the 12-volt output.

• Only switch on the AC side (230 volts) when you actually need it.

Recharging: driving, solar, and shore power

Nachladen während der Fahrt klingt praktisch – bringt aber wenig. An der 12-Volt-Steckdose laden die meisten Powerstations mit etwa100 to 120 watts. A half hour of driving gets you around 50 to 60 Wh. That's not even enough to run the cooler for half a day.

Solar helps more, but only in good weather. A 100 Wp panel delivers up to about 500 Wh on an ideal summer day in Germany. That assumes roughly five hours of full sun and good positioning. With clouds, shade, or a low sun angle, you get a lot less. In winter, you can barely count on solar at all. To meaningfully recharge a 2,000 Wh power station each day, you need more like 200 Wp or above.

What to look for when buying

Capacity is just one number. These points matter just as much:

1. Continuous inverter output: It has to cover your most power-hungry device, plus a 20 to 25 percent buffer. A kettle or coffee machine needs 1,500 watts or more, a hairdryer or induction plate up to 2,000 watts.

2. Pure sine wave: Sensitive devices like espresso machines need clean sine-wave power. Established manufacturers now offer this as standard, but cheap devices don't always.

3. LiFePO4 battery type: Lithium iron phosphate is safer and lasts longer than classic lithium-ion. Good units still have 70 to 80 percent of their capacity left after 3,000 to 4,000 charge cycles.

4. Connections: At least one USB-C port with Power Delivery for your laptop and a 12-volt output for the cooler.

5. Weight: Every kilo eats into your payload. From around 2,000 Wh upward, a power station gets too heavy to carry comfortably.

Is a power station even worth it?

In our podcast episode "Power stations & solar for camping – what's actually worth it?" we crunched the numbers. The result is sobering: in terms of electricity costs saved, a power station almost never pays off.

Podcast · Episode 284

Powerstations & Solar fürs Camping: Was lohnt sich wirklich?

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One example: a small Jackery 500 with solar panel costs around 530 euros. If you only use it to charge your phone, tablet, and laptop, you'll save 1.50 to 3 euros on campsite electricity over a two-week trip. Even at 80 cents per kilowatt-hour, it would take 88 to 176 years for the device to pay for itself. For a whole family, it's still over 20 years.

A power station can pay off in a different way, though: it lets you use spots without a power hookup. A private pitch for 15 euros instead of a campsite at 35 to 40 euros a night saves you far more than any kilowatt-hour ever could. For most people, though, a power station is mainly a comfort purchase. That's perfectly fine, as long as you go in knowing it.

What size for whom?

Weekend campers with phone, lights, and tablet (around 130 Wh per day): 300 to 500 Wh is enough for three to four days. You don't need solar for this.

Comfort campers with a compressor cooler, laptop, and some TV (around 500 to 1,000 Wh per day): 1,000 to 1,500 Wh for one to two days off-grid. A small 100 Wp solar panel extends that in good weather.

Campers using a coffee machine, hairdryer, or induction plate (1,500 Wh per day or more): start at 2,000 Wh, plus at least 200 Wp of solar. If you use that much power, it's also worth looking into a permanently installed leisure battery.

Our picks by price range

All four devices come from established manufacturers and use LiFePO4 batteries. Prices vary a lot, and deals are frequent.

EcoFlow River 3 Plus
286 Wh, 600 W continuous output, 4.7 kg, roughly 250 to 350 euros. Good for weekends with phone, lights, and laptop. Small enough to bring along to the tent or the beach.

Mid-range:

Anker SOLIX C1000 Gen 2

Enough for a cooler and electronics over a full day. The high continuous output can even handle a kettle now and then.

• 1,024 Wh

• 2,000 W continuous output

• 11.3 kg

• roughly 550 to 900 euros.

Premium:

Jackery Explorer 2000 v2

For comfort campers who want to go off-grid for two days. Small downside: solar charging maxes out at 400 watts.

• 2,042 Wh, 2,200 W continuous output

• 17.5 kg

• roughly 1,100 to 1,600 euros (currently 899.00 euros at Jackery – as of September 2026).

High-end:

EcoFlow Delta Pro 3

Powers even an induction plate and hairdryer, and can be expanded. At over 50 kilos, though, it's no longer really a portable power station. Check your payload beforehand.

• 4,096 Wh

• 4,000 W continuous output

• 51.5 kg

• roughly 3,600 to 4,000 euros

Alternative: the permanently installed leisure battery

With high power needs, a leisure battery is often the better solution. It charges much faster via the alternator while you drive, doesn't take up storage space, and can be combined with solar panels on the roof.

Here you need to factor in the depth of discharge. Lead-acid, AGM, and gel batteries should only be discharged to about 50 percent, while LiFePO4 batteries can go down to 80 to 90 percent. For the 1,500 Wh from our example, that means at 12 volts:

• LiFePO4: around 140 Ah, about 15 kg

• AGM: around 250 Ah, over 70 kg

The weight difference is huge. For most motorhomes, LiFePO4 is therefore the better choice, even though it costs more.

Bottom line

Whether a power station fits your needs isn't decided by the biggest number on the box, but by how you actually travel. If you mostly stay at sites with mains hookup, a small unit will do, or you might not need one at all. If you regularly camp off-grid, calculate your daily power usage honestly, build in a buffer, and buy accordingly. A power station that spends most of its time sitting in a cupboard is too expensive, no matter how cheap it was.