Choosing a Portable Power Station

A portable power station is a battery, an inverter, and a bunch of outlets in a box with a handle. The marketing leads with one big number — the Wh capacity — but that number alone tells you almost nothing about whether the unit will actually run your gear. A 2000Wh unit with a weak inverter can't boil a kettle. A 500Wh unit with a strong inverter can, just not for long.

Picking the right one comes down to matching four things to your use case: how much energy it stores, how much power it can push, what you plug into it, and how fast it refills. Get those right and you'll pay for exactly the unit you need.

The two numbers that matter most

Just like a home battery, a portable station is spec'd by energy and power, and they're not interchangeable.

• Energy (Wh) — how much total charge it holds. Determines how long it runs a load.
• Power (W) — what the inverter can push out continuously. Determines whether it can run a load at all.

You need enough of both. A big battery with a small inverter runs small things for a long time. A small battery with a big inverter runs big things briefly. Only a unit sized for both does what you want.

Capacity: nameplate Wh vs usable Wh

Manufacturers print the nameplate Wh — the raw cell capacity. What reaches your device is less, because the inverter (DC → AC conversion) loses roughly 10–15% as heat.

The working rule:

Runtime (hours) = usable Wh ÷ device watts

where usable Wh ≈ nameplate × 0.85. So a "1000Wh" unit delivers about 850Wh to an AC load.

Worked example: what a 1000Wh unit actually runs

Device	Draw	Hours on ~850Wh usable
Phone charge	10W	~85 (dozens of full charges)
CPAP (no humidifier/heat)	30W	~28 (3–4 nights)
CPAP (with heated humidifier)	60W	~14 (1–2 nights)
Laptop	65W	~13
Wi-Fi router + modem	20W	~42
Mini-fridge (avg, cycling)	50W avg	~17
55" LED TV	100W	~8.5
Electric blanket (low)	60W	~14
Coffee maker / kettle	1000W	<1 (and only if the inverter allows it)

Notice the kettle: even if the inverter can push 1000W, a 1000Wh battery drains in under an hour running it. Heating anything — kettles, hair dryers, space heaters, induction cooktops — burns energy fast. Portable stations are for electronics and small motors, not sustained heat.

Output: continuous watts AND surge watts

This is the number people skip and regret. The inverter has two ratings:

• Continuous watts — what it sustains indefinitely.
• Surge (peak) watts — a brief spike it tolerates for a second or two, usually 1.5–2× continuous.

Anything with a motor or compressor — fridges, pumps, power tools — pulls a startup surge of 2–5× its running watts for a fraction of a second. A fridge that runs at 100W can spike to 600W on compressor start. If the surge exceeds the inverter's peak rating, the unit trips off, no matter how much energy is in the battery.

Pure sine vs modified sine. Cheap inverters output "modified sine" — a blocky approximation of the grid waveform. It runs simple resistive loads (lights, heaters) but can buzz, overheat, or damage sensitive electronics: CPAP machines, medical devices, variable-speed motors, some laptop chargers. Buy pure sine. Nearly all reputable modern stations are pure sine; verify before trusting a bargain unit with a CPAP.

Why a big battery can't run an AC or kettle. A 12,000 BTU window AC needs ~1200W continuous and surges higher on the compressor. A kettle pulls 1500W. If your unit's inverter caps at 1000W continuous, it doesn't matter that the battery holds 2000Wh — the load never starts. Match the inverter rating to your highest-wattage device first, then check capacity.

Chemistry: LiFePO4 (LFP) vs NMC

Two lithium chemistries dominate. The difference is real and worth understanding.

	LiFePO4 (LFP)	NMC
Cycle life	~3,000–6,000+	~500–1,500
Weight	Heavier per Wh	Lighter per Wh
Cold-weather charging	Tolerant, but no charging below freezing	Similar caution below freezing
Heat / safety	Very stable, hard to ignite	More sensitive to heat, higher fire risk
Best for	Almost everyone	Ultralight, occasional use

Recommend LFP for most people. It lasts several times longer, tolerates heat far better, and is the safer chemistry — which matters a lot for a unit that lives in a hot car, RV, or garage. NMC only wins when every gram counts (backpacking) and you'll cycle it rarely. Neither chemistry should be charged below freezing; both discharge fine in the cold at reduced capacity.

Ports: match them to your devices

Capacity and inverter get the attention, but you interact with the ports every day. Count what you actually plug in.

Port	What it's for	What to check
AC outlets	Anything with a wall plug	Count and inverter watt rating
USB-C PD	Phones, laptops, tablets	Watt rating — 30W charges a phone, 100W charges a laptop
USB-A	Older phones, accessories	Number of ports
12V car socket	Fridges, tire pumps, car gear	Present + amp rating
DC / barrel / Anderson	12V devices, some fridges	Only if your gear uses it

USB-C wattage is the common gotcha: a 15W port won't fast-charge a modern laptop. If you carry a laptop, look for at least one 100W USB-C PD port and skip the AC-adapter round-trip loss entirely.

Recharge: how fast it refills, and from what

A power station is only as useful as your ability to refill it. Three inputs matter:

• AC recharge speed (W). How fast it charges from a wall outlet. Budget units trickle at 100–200W (8+ hours for 1000Wh); good ones pull 500–1500W and refill in about an hour. For short-outage use, fast AC recharge is the single most useful spec — top it off before the next event.
• Solar input. For off-grid and camping. Check three things: an MPPT charge controller (harvests far more than cheap PWM), the maximum solar watts it accepts, and the Voc voltage window — your panel's open-circuit voltage must land inside the unit's range or it won't charge (or gets damaged). More panel watts = faster refill, up to the unit's cap.
• Car charging. Slow (typically ~100W from a 12V socket) but useful for topping up while driving between campsites.

Pass-through charging lets you run devices while the unit itself is charging — the station acts as a UPS. Handy for a CPAP on a campsite with intermittent shore power, or as a desk backup. Confirm the unit supports it; not all do, and some warn against it for battery longevity.

Portability: weight vs capacity

Every Wh has weight. LFP runs roughly 10–15 kg per 1000Wh; a 2000Wh unit is genuinely heavy to carry any distance. Be honest about whether you're hauling it to a campsite or wheeling it from the garage to the driveway.

Expandable ecosystems are worth a look if your needs might grow: some brands let you clip on add-on batteries so the base unit's inverter serves a larger pack later. You buy the inverter once and scale the energy — useful if you start with weekend camping and later want short home backup.

Sizing by use case

Start from what you're powering and how long, then buy the smallest unit that covers it.

Use case	Typical loads	Suggested Wh	Inverter to check
CPAP overnight	CPAP 30–60W × 8h	300–600Wh	Small, but pure sine
Weekend camping	Lights, phones, fridge, fan	500–1000Wh	300–1000W
Tailgate	TV, blender, speakers, lights	500–1500Wh	1000W+ for blender surge
Short home outage	Fridge, router, lights, phones	1000–2000Wh	1500W+ for fridge surge
RV / van base	Fridge, water pump, devices, charging	1500–3000Wh+	2000W+, expandable

CPAP users: check whether your machine's heated humidifier is on — it can double or triple draw. Run it dry (humidifier off) on battery and a 500Wh unit covers multiple nights.

What to avoid

• Buying on nameplate Wh alone. Usable energy is ~85% of the sticker, and the inverter rating decides what you can even plug in. The big number is marketing.
• Ignoring the inverter watt rating. A huge battery with a 1000W inverter still can't run a 1500W kettle or a window AC. Match the inverter to your biggest load first.
• Modified-sine for sensitive electronics. CPAPs, medical gear, and variable-speed motors want pure sine. A cheap modified-sine unit can buzz, overheat, or damage them.
• NMC in a hot car or RV. Heat is where NMC is weakest. For a unit that lives in a vehicle, garage, or trailer, choose LFP for safety and lifespan.
• Assuming solar "just works." Wrong panel voltage (outside the Voc window) or a cheap PWM controller means slow or no charging. Check the input spec against your actual panels.
• Over-buying capacity for CPAP or camping. A 2000Wh unit is heavy and expensive. If you only run a CPAP and charge phones, a 500Wh unit is lighter, cheaper, and enough.

Portable vs installed home backup

A portable station and a home battery solve different problems:

	Portable station	Installed home battery
Powers	A handful of devices you plug in	Whole house or a critical-load subpanel
Capacity	0.3–3 kWh	10–40+ kWh
Install	Unbox and go	Electrician, permits, transfer switch
Cost	$200–$3,000	$10,000–$40,000
Best for	Mobility, CPAP, camping, brief outages	Multi-day outages, solar self-consumption, peak shaving

If you want the fridge, furnace fan, and well pump to ride through a multi-day outage automatically, that's the whole-home case — see Sizing a Home Battery. If you want to keep a CPAP running through the night, charge devices at a campsite, or bridge a two-hour outage, a portable station is the right, far cheaper tool.

How to use PowerUsage to choose

You don't have to guess at runtimes or compare spec sheets by hand.

1. Battery Runtime — add a portable unit and the devices you plan to run. It calculates how many hours the station carries your combined load, so you can see whether a 500Wh or a 1500Wh unit actually covers your CPAP night or camping weekend. The tabs also cover run-time and charge cost, so you can check what a full recharge costs on your rate.

2. Device Catalog — browse batteries, including portable power stations, with their real specs (usable Wh, continuous and surge watts, chemistry, ports, recharge input). Add candidates to your list.

3. Compare — put two or three units side by side to see capacity, inverter rating, chemistry, and recharge speed against each other. This is where the marketing melts away and the unit that actually fits your loads stands out.

Run your real device list through Battery Runtime before you buy. It's the difference between a unit that quietly covers your use case and one that trips off the first time you plug in the kettle.

The bottom line

A portable power station is the right tool for mobility and short outages — CPAP nights, camping, tailgates, RV base power, and bridging a couple of hours when the grid blinks. Buy on four numbers, in this order: inverter watts (can it run your biggest load?), usable Wh (how long?), ports (does it fit your devices?), and recharge speed (how fast back to full?). Choose LFP unless you have a specific reason not to, insist on pure sine for anything sensitive, and size to your actual loads rather than the biggest number on the box. If your real need is whole-home, multi-day backup, that's a different purchase — see Sizing a Home Battery.