How To Choose The Best Portable AC Power Supply


If you want to power or charge a small, AC-based device such as a laptop when power outlets are out of reach, you should get the ChargeTech Portable Power Outlet (27 Ah). It’s essentially the same thing as a USB-only battery pack, but with higher capacity and an AC outlet. The ChargeTech stood out among the small models we tested because it offered the best balance of size, capacity, and price. About the size of a small hardcover book, it’s compact enough for you to carry it in a laptop bag, backpack, or carry-on, but it holds enough energy to completely charge a large laptop—or charge the smallest models two or three times over. If you need to power more than just a laptop or some other small device but a gas generator is out of the question, we like the Goal Zero Yeti 400 Solar Generator for its higher capacity and output, as well as its top-notch build quality—even if it’s too big and too heavy to lug around all the time.

Most mobile electronics can charge just fine from USB battery packs, any of which are smaller and less expensive, and built with fewer complicated circuits, than the picks in this guide. But a pack with a standard AC outlet is a more versatile power source, suitable for the odd situations when USB won’t do the trick. For example, if you frequently work away from a traditional desk, or if you have a laptop with subpar battery life, a portable AC power pack lets you roam farther than just the one table near the outlet at your local coffee shop. If you’re in the car for hours on end with your family, a pack can keep toys and games charged so cranky kids (and adults) stay entertained. If you’re a frequent flier, you can plug in a laptop on a long flight without needing to pay a premium for a seat with an outlet—and without needing to carry single-use adapters. The more power you need, however, the more expensive and unwieldy the AC power pack.

After more than 20 hours of testing, the hardcover-size ChargeTech Portable Power Outlet (27 Ah) emerged to earn a place in our backpacks and laptop bags. This 2-pound, lithium-battery-based pack gave us a handful of charges for a tablet, a few charges for a small laptop, or an extra charge for a large laptop—in contrast, one smaller and less expensive pack we tested was capable of getting our 2012 11-inch MacBook Air up to only around 50 percent of a full charge. Although the Portable Power Outlet isn’t cheap enough to be an impulse buy, many laptop users will have plenty of opportunities to get their money’s worth from it.

The Goal Zero Yeti 400 Solar Generator is based on bulkier, lead-acid batteries that make it much larger and heavier than the ChargeTech Portable Power Outlet—this 30-pound block would just about fit in a standard plastic milk crate. But the Yeti 400 offers about four times the capacity of the Portable Power Outlet at only twice the cost. You also get a lot more versatility thanks to a large, pure-sine-wave inverter that outputs 300 watts of power, outclassing the 90-watt output of the ChargeTech unit. And if you’re powering up multiple devices, this Goal Zero model provides not only an AC outlet and two USB ports like the ChargeTech but also a second AC outlet, three DC outlets, and the capability to recharge with optional solar and vehicle accessories. If you have the budget and don’t need to carry your battery pack much, the Yeti 400 offers the most reliable way to get a lot of power without relying on a gas generator.

Who this is for

You need an AC power source if you want to charge devices that require AC power, such as laptops and camera-battery chargers, or if you want to power AC-based devices like lighting equipment, fans, or certain music gear. Most of the Wirecutter and Sweethome staff works remotely, all over the country, so we see these products as offering the ability to work when traveling—on planes, on trains, or when you’re stuck at a café table without an outlet nearby. But they can also come in handy at conferences and conventions, on road trips, on photography expeditions, or during technology-heavy outdoor adventures.

Our smaller pick, the ChargeTech, is better suited to a single user looking for a short-term option—for example, if you need to power a laptop at a coffee shop or airport and you don’t have access to an outlet. Because this pack should be able to power most portable electronics for one sitting, it’s the best choice if you will be able to get to an outlet later in the day.

If you’re going for longer stretches away from the grid, if you have a large device to power, or if you want to take care of multiple smaller devices, you need to move up a category. Weighing 10 to 30 pounds, larger packs such as the Goal Zero Yeti 400 are meant to be kept in a vehicle or lugged to a single spot to stay put for a while—think of car camping or tailgating, portable presentations, or on-location work for everyone from construction crews to photographers. Though the capabilities of such overgrown battery packs pale in comparison to the output of a gas generator, they’ll quietly power your gear in places where a noisy generator isn’t practical.

You don’t need one of these packs if you’re looking to power small devices like smartphones, tablets, or Wi-Fi hotspots. If everything you have can work with USB power, you can get the same capacity for as little as a third of the cost with a traditional USB-only battery pack.

If you plan to power anything with a motor—such as a corded drill or saw—the modified-sine-wave output of the less expensive models, including our ChargeTech pick, may cause problems like inconsistent speed, heat buildup, or higher-than-normal power draw. And for the highest draws, from equipment such as power tools, appliances, or anything that heats or cools, you need a lot more power than the current generation of batteries and portable inverters can provide. In that case, you should look into a gas generator instead.
Why you should trust us

Though The Wirecutter and The Sweethome have a handful of offices scattered around the country, we’re mostly a remote organization. We’re often writing from coffee shops, scouting new gear at trade shows, testing products out in the woods, or driving across the desert to make sure our picks work as intended. In short, we’re exactly the people who want quiet, affordable, and portable AC power packs.

Personally, I travel full-time in an RV and am just as likely to be working from a state park as a café or library. Even though I have over 700 watts’ worth of solar panels and about 500 pounds of batteries, I never know where my next charge will come from, and I often wander away from my onboard outlets. In addition to testing these packs, I’ve researched and tested hundreds of USB battery packs for The Wirecutter, along with other power products such as surge protectors, uninterruptible power supplies, and solar chargers. At this point, I probably spend more time thinking about electricity than most electrons do.

If you need an AC outlet slapped on a battery, you don’t have many choices—the 12 models we seriously considered make up the bulk of the options when it comes to portable, affordable AC power sources. A few of them were released just in the past year, bringing some competition to an otherwise quiet category.

We split our dozen models into two groups based on capacity and price. Our main group of smaller batteries included eight models with a range of capabilities, priced from just over $100 to about $400. Some of them are based on mature, lead-acid battery technology, which makes larger capacities cheaper but much heavier. More-recent models use lithium-based batteries, which cost a lot more but weigh a lot less. Some models are simple, offering a single outlet; others have options such as car chargers or solar panels. Because of the range in features, purpose really drove our definition for this group: We wanted something that was reasonably affordable and made sense for a carry-on, laptop bag, or backpack, so we focused on the most portable models—generally lithium-based units that weigh less than 5 pounds. We narrowed the options further by looking at the dollar-per-watt-hour value of each unit and by sticking with well-regarded brands that are readily available at trusted retailers. We then tested the three most promising models: the Xcellon PB-1200AC 12,000mAh Power Bank with AC and USB Outlets, the ChargeTech Portable Power Outlet (27 Ah), and the Goal Zero Sherpa 100 Power Pack with a Sherpa Inverter.

Because none of these smaller models pack enough power for the additional gear that outdoor enthusiasts or field professionals might want, we also looked at larger options. Once you commit to spending $500 or more, you can choose from a handful of larger models that emphasize capacity over portability. (Spend over $1,000, and you can get power for days, but because those products are the size of a small generator and the weight of a baby elephant,1 we left out the biggest ones.) Though some additional models may crop up later in the year, we wanted to keep the focus on products you can purchase today. In the larger-models category, the Goal Zero Yeti 400 promised the best balance of price and capacity, so we tested it to see if the extra heft would be worth the investment for people who need more power than our top pick can provide.

We wanted something that was reasonably affordable and made sense in a carry-on, laptop bag, or backpack—generally a lithium-based unit that weighs less than 5 pounds.
Regardless of the size, an AC-capable battery is really just a small inverter mated to a battery pack—whether the battery is lead-acid (like a car battery) or lithium polymer (like a laptop battery) doesn’t really matter. The inverter takes the DC power of the battery and turns it into the AC power that a standard North American AC outlet normally pumps out. To test each of the products, we wanted to look at both the amount of power that the battery stored and the consistency of the power that the inverter put out.

To get data on the various batteries, we charged each unit to full and then drained it using a 50-watt light bulb—our easily reproducible stand-in for a small laptop. We monitored the power usage and cumulative watt-hours with a simple Kill A Watt meter. To check for variation, we repeated the process three times with each model. Because a single light bulb running at a steady load isn’t quite what most people would use these batteries for, we also checked the performance in the light-bulb test against a test using a 2012 11-inch MacBook Air.

In addition to those measures of capacity, we considered how many watts each battery could put out at a given moment. If you try to pull too much power at once, the device shuts down until you remove the load, just like a breaker tripping in your house. The smaller packs have only one plug for a reason—you can’t expect to power more than a single device, and not anything more demanding than a large laptop.