Portable Power Stations
What Size You Actually Need

1Start here: does your van already cover it?

Before you spend anything, look at what the van already carries. Modern Australian caravans are far better equipped for free camping than they were a decade ago, and a fair few owners buy a power station to duplicate capacity they already had.

Modern Australian caravans carry more solar and battery than they used to. As a sense of scale, a typical roof array runs around 600W and the biggest reach 3,000W. A typical battery bank is about 300Ah, which is roughly 3,600Wh of nameplate energy at 12V. Treat those as a feel for the range, not an industry average.

Put that next to the boxes on sale and the picture changes. A median van with a 300Ah bank already has more nameplate energy on board than most single power stations, and a roof array that refills it every sunny day for free.

The catch, and it is a big one

A big battery and a big roof array still tell you nothing about whether a van can run a 240V appliance. That job belongs to the inverter, and a stated inverter rating is rare on a caravan spec sheet. It is the figure that decides what a van can actually power.

That matters more than any other figure here, because the battery bank is only half the story. A van can carry 300Ah and a big roof array and still have no way to run a 240V appliance, and the brochure usually will not tell you. Ask the dealer, in writing, before you assume either way.

This is the honest case for a portable unit. It arrives with its own inverter and its own outlets, so it sidesteps the specification the brochure almost never gives you. That is a genuine gap it fills, and it is a different argument from "you need more battery".

Worth knowing too: plenty of vans really are set up for powered sites, with modest battery banks under 200Ah, and their owners are the ones this purchase actually suits.

2What the numbers on the box mean

Four specifications decide whether a unit suits you. The marketing usually leads with the first one alone.

Capacity, in watt-hours

Watt-hours (Wh) are how much energy the unit holds. This is the number to compare across brands, and it is the one to convert your caravan battery into as well: watt-hours are roughly amp-hours multiplied by volts, so a 100Ah battery at 12V is about 1,200Wh on paper.

You will not get all of it. Between the depth of discharge the maker recommends and the losses in converting battery power to 240V, planning on roughly 85% of the rated figure is the sensible habit. That is a rule of thumb drawn from typical manufacturer guidance, not a promise about any particular unit.

Continuous output, in watts

Capacity says how long. Continuous output says what you can plug in at all. A big battery with a small inverter still will not run a kettle, and this is where people get caught: they buy on capacity and discover the output rating is the real limit.

Add up what you would run at the same time, in watts, and make sure the continuous rating clears it with room to spare.

Surge rating

Motors and compressors draw far more on startup than they do once running. The surge (or peak) rating is what covers that moment. A unit whose continuous rating looks fine can still trip when the fridge compressor or a power tool kicks in, so check both figures.

Chemistry and cycle life

Most current units use LiFePO4 cells, and the good ones publish a cycle rating: how many charge and discharge cycles before the battery drops to a stated share of its original capacity. A unit rated for a few thousand cycles is in a different class from one rated for a few hundred, and that difference matters far more over ten years of trips than a small gap in capacity.

If a spec sheet does not mention chemistry or cycle life, treat the silence as information.

3The sizing maths, done honestly

Work out what you use in a day, then buy enough for the number of days you want between charges. That is the whole method. The trick is being honest about the daily figure.

Step one: your daily watt-hours

For each appliance, find the wattage on its compliance label, then estimate the hours a day it actually draws power. Multiply the two. Things that cycle on and off, like a fridge, do not run continuously, which is where most estimates go wrong in the optimistic direction.

A worked example, with every assumption stated because they are all assumptions:

Six hundred watt-hours a day, on those assumptions. Your fridge, your weather and your habits will move that figure, which is the point of doing it with your own labels rather than borrowing someone else's total.

Step two: multiply by your days, then add the losses

Two nights at 600Wh is 1,200Wh of demand. Allowing for that 85% usable habit, you are shopping for something rated near 1,400Wh, not 1,200Wh. Round up rather than down, because the day it matters is the overcast one.

If a decent roof array is topping the unit up each day, the same box stretches much further. That is a real effect, not a marketing one, and it is why the charging section below matters as much as the capacity.

Step three: the three size classes

In practice the market sorts into three bands, and once you have your daily figure you will know which one you are in.

• Around 500Wh. Devices, lights, a CPAP for a night, topping up a fridge that is mostly running off the van. A weekend unit. Light enough to carry one-handed.
• Around 1,000Wh to 1,500Wh. The mainstay. Covers the worked example above for two days or so without solar, and runs a fridge plus devices comfortably with a panel attached.
• 2,000Wh and up. Extended stays, higher-draw appliances, or running a fridge without relying on sunshine. Heavier, and the weight comes out of your payload.

4Power station, generator, or more battery in the van?

Three different tools, and the box is not automatically the right one. Two of these three earn us nothing.

A portable power station wins when

You want no installer and no holes in the van. You want the same unit to work at a picnic table, in the tent, and in the house when the power goes out. You want it to come with you to the next van. And you need 240V outlets that your van may not be able to give you, which as noted above you often cannot confirm from a spec sheet.

A generator wins when

You need to make power rather than store it. A generator keeps going as long as you keep feeding it, which no battery does, and that is the honest advantage for long stays in poor weather or for high-draw appliances.

The costs are noise, fuel, servicing and welcome. Many caravan parks and campgrounds restrict when generators may run, and some prohibit them, so check the rules for where you are going rather than assuming. Your neighbours will have opinions too.

More battery in the van wins when

You are staying with this van, you already have an inverter, and you want the cheapest usable watt-hours. Installed capacity charges itself off the roof and the car while you drive, takes up no floor space, and does not need lifting. Per watt-hour it is usually the better buy.

The tradeoffs are that it costs installation, it needs a licensed electrician, it stays with the van when you sell it, and it does nothing for you at the beach or during a blackout at home.

5When not to buy one

Four situations where the money is better left in your pocket or spent elsewhere.

• You stay on powered sites. If your travel is park to park with a 240V post at every stop, a power station is an expensive way to own a spare. A decent extension lead and a surge protector cover you.
• Your van already has installed lithium and an inverter. You would be buying a second, smaller version of what you own. Confirm what is fitted first, in writing from the dealer, because the spec sheet will not tell you.
• You want off-grid air conditioning. This is the most common disappointment. A rooftop unit draws heavily on startup and then keeps drawing, so a portable box that technically starts it can still be flat well before you are comfortable. If this is the goal, you want a properly specified installed system or a powered site, not a box.
• Your payload is already tight. A big unit is serious weight, and it competes with water, gear and everything else in your allowance. Check the unit's published weight against what you actually have spare. If you do not know your spare payload, work it out before you shop, not after.

6Keeping it charged

A power station you cannot refill is a very heavy battery. How you top it up decides whether the capacity you bought is enough.

From mains. Fastest, and the one to use the night before you leave. Check how long a full charge takes, because it varies enormously between units.

From the car while driving. Useful on travel days, usually slow through a 12V accessory socket. If you move every day or two, this alone can keep a modest unit in the game.

From a portable solar panel. The one that changes the maths for stationary camping. A folding panel plugged straight into the unit adds daily energy without touching the van, and it is the difference between a box that lasts two days and one that lasts as long as the weather holds. Match the panel to the unit's stated input limit and connector rather than buying on wattage alone.

7What to check on any brand's spec sheet

Take this list to whichever brand you are looking at. It is deliberately brand-neutral, and a unit that answers all seven clearly is usually a unit from someone who expects to be held to it.

• Capacity in watt-hours, stated plainly, not only as amp-hours at an unstated voltage.
• Continuous output in watts, and the surge rating as a separate figure.
• Cell chemistry and a cycle rating with the capacity level it is measured to.
• Maximum solar input and the connector type, so a panel you buy later actually fits.
• Weight, because it lands in your payload.
• Australian warranty terms and the length, from an entity you can contact here.
• Local support and spare parts. A cheap unit with no local service is expensive the day it fails.

8Common questions