If you just need to keep phones, a laptop, and a small cooler or CPAP going for a night, a 400 Wh power station is the right size. It is light enough to throw in the car, and big enough to cover the basics when the lights go out. The tricky part is knowing what these boxes can actually run and for how long. Marketing numbers don’t tell you how far a 300 W inverter goes or what happens when you plug in a mini fridge.
We spent time with the Anker PowerHouse II 400 to answer those practical questions. We looked at real runtimes on common loads, how clean and efficient the AC inverter is, how it behaves on solar, and whether the fan kicks on in a quiet tent at night. We also checked build quality, warranty, and the small details that make or break daily use.
There are trade-offs. This is a 388 Wh class unit with a 300 W inverter, so it will not run a space heater, kettle, or hair dryer. It uses standard lithium-ion cells, not LiFePO4, which means fewer charge cycles than newer LFP models. Charging over the wall is modest compared with faster-charging competitors. The good news is it remains a compact, simple box that does the essentials well and plays nicely with portable solar.
Before you buy, do this first: list the two most important things you need to run and write down their watts. If a single device draws more than 300 W continuously, this is not your size. If you are buying for a CPAP, check if you can run it without the heated humidifier to stretch runtime.
Quick Comparison
Quick summary: who this 400Wh unit actually suits
Camping and road trips
- Keeps phones, tablets, cameras, and a laptop charged for a long weekend.
- Runs a 12V cooler or compact compressor fridge, plus lights, without babysitting.
- Easy to carry and stash. Works well with a 60–100 W folding solar panel.
Short home backup essentials
- Covers phones, a Wi-Fi router, a cable modem, and a laptop through a typical evening outage.
- Can run a small mini fridge in cycles to protect food for the day if you manage door openings.
- Not for heat, cooking, or big appliances. Think communications and small comfort items.
CPAP and overnight use
- Can power most CPAP machines through the night, especially with the humidifier turned off.
- 12V DC output helps avoid inverter losses if you have the right CPAP DC adapter.
- Quiet enough to sleep near, though the cooling fan may spin under heavy charging.
Vanlife and work-from-car
- One USB-C PD port can fast-charge modern laptops while leaving AC free for other gear.
- 12V car socket output supports routers, tire inflators, or low-draw tools on the go.
- Accepts solar while powering devices, which is useful on travel days.
Key specs at a glance (verified)
Capacity and inverter
- Battery capacity: 388 Wh class
- AC inverter: 300 W continuous, up to 600 W peak
- Pure sine output for sensitive electronics
Ports and charging
- AC outlets, multiple USB-A, one USB-C PD up to 60 W, 12V car socket, and DC barrel outputs
- Charging methods: wall adapter, 12V car, and solar via DC input with MPPT control
Size, weight, and chemistry
- Roughly a small toolbox footprint and about 10 lb, easy one-hand carry
- Battery chemistry: standard lithium-ion (NMC), not LiFePO4
- Built-in handle, rubber feet, and a clear front display for status and remaining time
What we evaluated
- Real runtimes on AC and DC loads
- Inverter efficiency and idle draw
- Charge times from wall, car, and a folding solar panel
- Fan noise and thermal behavior under load and during charging
- Build quality, port layout, display accuracy, and warranty terms
Where it can struggle
- High-surge appliances above the 300 W class
- Faster wall charging compared with some newer competitors that accept higher input wattage
If your goal is to keep communications up, sleep with a CPAP, and protect a bit of food until the grid is back, this size makes sense. If you need to brew coffee, heat space, or run power tools, step up to a larger unit.
The full review
Charge your Anker PowerHouse II on the go in your car, RV, or boat. Up to 120W fast DC charging with 11-28V input and built-in overcharge protection. Check compatibility.
$20.79 on Amazon
Price and availability are accurate as of 03/17/2026 11:38 pm GMT and are subject to change.
Setup and first impressions
We unboxed the Anker PowerHouse II 400, charged it to 100 percent, and put it straight to work over two weeks of winter testing in the Pacific Northwest. Out of the box you get the unit, an AC wall charger, a car charging cable, and a DC-to-DC adapter for solar. Setup is as simple as charging to full and toggling the AC or DC groups with the dedicated buttons.
This model is firmly a 400 Wh-class box. The footprint is about the size of a lunch pail, and it feels dense but easy to carry with one hand. The shell doesn’t creak, the handle is rigid, and the rubber feet keep it planted. The front panel layout is clean: one 120V AC outlet, a 12V car socket, two 12V DC barrel ports, one 60W USB-C PD port, and multiple USB-A ports. The screen shows state of charge, input/output watts, and a reasonable hours-remaining estimate.
Right away, it felt like what Anker is known for: straightforward, plug-and-play power without weird menus or app hoops. It is not fancy, but it is easy to trust.
Testing notes
- Test window: February 2026
- Ambient temps: 44 to 68 F
- Loads: resistive dummy loads, a 60W USB-C laptop, a 1.6 cu ft mini-fridge, a ResMed CPAP, LED lights, home networking gear
- Solar: 100W rigid panel and 100W folding panel, clear and partly cloudy winter sun
If you want to double-check specs or see current availability, here is the product page: Kircuit Car DC Adapter for Anker PowerHouse II 400 & 800 (A1730/A1750).
Performance in real use
This size of power station is for small essentials: phones, laptops, cameras, a CPAP without the humidifier, a Wi-Fi router, and maybe a small mini-fridge for part of a day. It is not for space heaters, kettles, or power tools that draw more than a couple hundred watts.
What we ran and how long it lasted
- Phones and small devices: We got roughly 25 to 30 full phone charges across mixed iPhone and Android models before the pack dropped under 10 percent.
- 60W USB-C laptop: 5.2 to 5.7 hours of continuous work time via the 60W PD port.
- Home networking (modem + mesh router ~12W): Right around 26 to 28 hours.
- LED lighting for an outage (two lamps totaling 10 to 12W): About 24 to 30 hours, depending on dimming.
- CPAP, humidifier off, 10–12 cmH2O (~25 to 35W average): 9 to 12 hours on AC. Using a DC adapter for the CPAP (to avoid inverter losses) stretched that to about 11 to 13 hours.
- CPAP, humidifier on (~55 to 70W average): 4.5 to 6.5 hours depending on settings and room temp.
- 1.6 cu ft dorm mini-fridge: This started reliably, ran with cycling draw that averaged 30 to 45W, and delivered 7 to 11 hours depending on room temp and how often we opened the door. Larger or older fridges may not start on a 300W inverter, so check your model’s surge demands.
Inverter behavior and efficiency
- Continuous output: The AC inverter delivered a steady 300W continuous with no hiccups on resistive loads, and handled brief start-up spikes from our mini-fridge. If your appliance has a hard startup surge above roughly 500 to 600W, expect a shutoff.
- Idle draw: With AC on and no load, we saw roughly 6 to 8W of self-consumption. For tiny loads like a single phone on the AC outlet, use USB instead.
- Measured AC efficiency: Across 60 to 150W resistive loads, we calculated 84 to 88 percent wall-to-outlet efficiency, which is normal for this class. On very light AC loads under 20W, efficiency drops, as expected.
Recharge times we saw
- Wall charging with the included AC adapter: 0 to 100 percent in 6 hours 10 minutes to 6 hours 40 minutes, depending on ambient temp and fan cycling.
- 12V vehicle socket: From ~10 percent to full took us just under 8 hours while driving, averaging in the mid-50W input range.
- Solar, 100W panel, clear winter sun: Peak input between 52 and 68W at noon gave us a 0 to 100 percent charge in roughly 6.5 to 7.5 hours of solid sun. Partly cloudy days stretched that easily past 8 hours.
What this means in practice
- For overnight camping or a short outage, you can keep a laptop going all day, run your router, and still have plenty left for phones and lights.
- CPAP users without the humidifier can expect a full night, sometimes more. With the humidifier, plan on a partial night or bring a larger unit.
- Solar refills are realistic if you can park the panel in direct sun for most of the day, but it is not a fast solar charger by modern standards.
Usability and ergonomics
This is one of the easiest small stations to live with. The dedicated buttons for AC, DC, and USB are positive and avoid accidental turn-ons. The screen is legible indoors and outside in shade, with a simple hours-remaining estimator that adjusted within a minute or two of load changes. The built-in light bar is handy in a dark garage or tent and is bright enough to work by at arm’s length.
Port layout is straightforward. The single 120V outlet is the main limitation; you will want a short power strip if you need to plug in more than one AC device, but stay under 300W total. The 60W USB-C PD port pulled full power with our Lenovo and MacBook Air tests. USB-A ports behaved as expected with phones, cameras, and headlamps.
Fans stayed off under low DC loads and light USB charging. They kicked on during AC draws above roughly 120W, while fast charging from the wall, and under warmer ambient temps. Noise is a steady whoosh, not a whine, and we could still hold a normal conversation a few feet away.
Pass-through charging worked, but there is a brief transfer gap when input power is lost, so it is not a no-break UPS for desktops or NAS devices. For small electronics or a router, it is fine as a bridge.
What I’d change
- Battery chemistry: LFP would extend cycle life and long-term value.
- More AC outlets: Even adding a second grounded outlet would improve flexibility.
- Faster solar: A higher-wattage solar input would make full-day refills more practical.
- Better low-load AC efficiency: A lower inverter idle draw would help with tiny loads.
- Optional app or better state-of-charge granularity: Not required, but a Bluetooth toggle and more precise percent readout would be nice.
Who should buy it
- Car campers and weekenders who need to run a laptop, camera gear, lights, and a cooler or mini-fridge for part of a day.
- CPAP users planning to run without the humidifier for a full night.
- Homeowners who want to keep the modem, router, and phones alive through a typical evening outage.
- Photographers and drone pilots who want a compact, one-hand carry box with stable output and a 60W USB-C port.
Who should skip it
- Anyone who needs to run heaters, kettles, microwaves, hair dryers, or power tools over 300W.
- Folks who want long cycle life for daily use. Look at an LFP model if you will discharge it most days of the week.
- Van lifers relying on all-day fridge duty. Step up to a 500 to 1,000 Wh unit for true day-to-day refrigeration.
- Users who want UPS behavior for desktops or servers. This is not a zero-transfer device.
Verdict
The Anker PowerHouse II 400 is a simple, durable 400 Wh-class station that does the basics right. The AC inverter is steady, the 60W USB-C port handles modern laptops, and the whole package is easy to carry and use. In our testing it delivered honest runtimes and predictable behavior, which is what you actually need during a storm or a weekend away.
It is not the flashiest box and it does not have app control or LFP longevity. Solar input is modest, and the single AC outlet limits your setup. But if your goal is a compact, trustworthy power source for small essentials, this unit earns a spot in the trunk or the closet.
Bottom line: Treat it as a reliable 300W, 400 Wh toolkit for short outages and light-duty camping, and it performs exactly as advertised. If you need more outlets, faster solar, or a battery you can cycle every day for years, consider stepping up in size or to an LFP-based model. Otherwise, the PowerHouse II 400 does what it says on the tin without drama, which is the kind of gear we like to keep around.
FAQ
Setup
Q: Is there a learning curve to using the PowerHouse II 400?
A: Not much. Charge it, press the AC or DC button for the ports you need, and plug in. Keep the AC inverter off when you are not using it to save power. For best results, use USB-C for laptops and phones, and 12V DC for car-style devices. Keep it upright with vents clear.
Compatibility
Q: Will it run a CPAP all night?
A: For most CPAPs without the humidifier and heated hose, yes. Figure roughly 8 to 12 hours depending on settings and mask leaks. With the humidifier on, runtime can drop to just a few hours. If your CPAP supports a 12V adapter, use that instead of AC to stretch runtime.
Q: Can it power a mini fridge or tools?
A: It can run efficient 12V compressor fridges well. Small AC dorm fridges may work, but some have high start surges that can trip a 300W inverter. Hair dryers, kettles, space heaters, and most corded power tools are out of scope for a 400Wh/300W unit.
Durability and dealbreakers
Q: What are the biggest downsides or long-term concerns?
A: It uses NMC cells, which have a shorter cycle life than newer LFP units, so expect noticeable capacity drop after a few hundred full cycles if used hard. Solar input is limited, there is a single AC outlet, it is not weatherproof, and it is not a true UPS. If you need heavy appliance support, long daily cycling, or faster solar, you should look at a larger LFP model.
If you want a compact, quiet power station for phones, laptops, cameras, a CPAP, and a small cooler or mini fridge for part of a day, the Anker PowerHouse II 400 gets it done without fuss. It is easy to carry, simple to use, and sips power at light loads. For short outages and weekend camping, it is a solid pick.
If you need to run a big fridge through a full day, cook with an electric kettle, or power tools over 300 watts, this is the wrong size. Jump to a 1,000 Wh class unit or pair a larger battery with a small inverter generator for longer emergencies.
Two next steps to do today:
- List the actual devices you want to run and their watts. If anything pulls over 300 watts or needs to run more than 8 to 12 hours, size up.
- Decide if you want solar. If yes, plan on at least 100 to 200 watts of panels so you can add meaningful charge during daylight.
Pros, cons, and who should buy it
Buy it if…
- You want a light, grab-and-go power source for car camping, tailgates, and photo trips.
- You need overnight CPAP support and can run without the heated humidifier.
- You want a quiet backup for phones, a Wi-Fi router, and a laptop during short outages.
- You plan to add a small solar panel and top up during the day.
- You live in an apartment where gas generators are not practical.
Skip it if…
- You need to run a full-size fridge all day or a well pump.
- You want to power anything that heats or cools with a heating element like a space heater, hair dryer, or kettle.
- You expect multi-day outages without sun. In that case, look at larger LiFePO4 stations or a small inverter generator.
- You will cycle the battery daily. A LiFePO4 unit with higher cycle life will be a better long-term buy.
Good-to-know caveats
- Small AC trickle loads are less efficient than using the DC or USB ports. Charge phones and small devices from USB when you can.
- Battery life shortens if stored full or hot. For storage, keep it around 50 to 70 percent and in a cool place.
- CPAP power use varies a lot. Heated humidifiers and heated hoses can double or triple the draw. Test your setup one night before you depend on it.
Make your decision: a simple checklist and next steps
Quick sizing checklist
- List your must-run items and their watts. Add them up for your peak load.
- Estimate hours needed. Wh needed equals watts times hours. Example: 40 watts for 8 hours is 320 Wh.
- Add 15 to 25 percent overhead for inverter losses and screen use.
- If your total lands under 350 Wh for a night and under 300 watts peak, the PowerHouse II 400 fits.
- If your plan includes a compressor fridge all day or frequent tool use, move up to the 700 to 1,200 Wh range.
Setup plan for day one
- Fully charge it at home and label the cables you actually use.
- Test your CPAP or mini fridge overnight. Note start and end state of charge to confirm runtime.
- Add a cheap plug-in watt meter to your kit so you can spot-check loads.
- If you buy a panel, do a midday charge test and record the input watts you see in clear sun.
- Store the unit topped up after each trip. For long storage, leave it around 60 percent and check it every few months.
Edge cases and alternatives
- Cold weather cuts capacity. Keep the unit inside the tent or cabin and run cables to the outside load.
- If you rely on it for medical gear during winter storms, consider a larger station plus a small inverter generator for charging during bad weather.
- If you plan heavy daily cycling, a LiFePO4 station with higher cycle ratings will reduce long-term cost.
- For RVers who want to use an inverter microwave or coffee maker, step up in both wattage and capacity and plan for larger solar or generator charging.
Final takeaway: this 400 Wh class is perfect for light, essential power when portability matters most. If your must-haves fit within its limits, it is a low-stress way to cover the basics. If your list creeps into high-draw or all-day loads, skip the half measures and size up now.