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.
Table of contents
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.
How we picked and tested
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.
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.
|MacBook Air (45 watts)||Toshiba Chromebook 2 (65 watts)||42″ LED LCD TV (75 watts)||15″ MacBook Pro, pre-2015 (85 watts)||Asus 17″ gaming laptop (130 watts)|
|Xcellon PB-1200AC (65 watts max)||Maybe|
|Goal Zero Sherpa 100 (100 watts max)|
|ChargeTech Portable Power Outlet (90 watts max)|
To get some idea of the inverter quality, we also used our Kill A Watt meter to check the unit’s voltage when under load and without a load, as well as the power frequency. Modern power supplies—the bricks on power cords—often include filters and circuits that ensure they provide good power to your devices.2 But power out of the standard frequency range, over- and under-voltage conditions, and noisy power can all degrade electronics slowly and cause them to reach their end of life sooner. All three of our small candidates use modified-sine-wave or pulse-width modulation (PWM) inverters, the cheapest versions of which are notorious for noisy or uneven waveforms; instead of the smooth wave of power that comes out of a standard wall outlet, PWM inverters put out power that steps up and down.
We asked electrical engineer Lee Johnson to examine each battery on an oscilloscope and generate the waveforms you can see above. They look pretty janky next to nice, smooth, pure sine waves, but they’re on a par with what we’d expect, and none stands out as better or worse than the others. Audio equipment and video gear may encounter unpredictable side effects, from static on analog signals (which can be audible on speakers or headphones, or visible on nondigital displays) to flickering power. Devices with motors—such as drills and saws—can sometimes run hot, at uneven speeds, or at higher-than-normal power consumption. For the most part, though, we’ve come to accept these waveforms as the cost of having portable AC power without spending a fortune.
Pure-sine-wave inverters, which perfectly mimic the power at home and help avoid occasional problems with finicky electronics, are available but are generally much more expensive. The larger Yeti line from Goal Zero, the Anker PowerHouse, and Renogy’s Firefly all use pure-sine-wave tech, but none of the smaller models we tested offer it.
All of those data points on capacity and power quality are important, but when you’re spending hundreds of dollars, build quality and usability quirks come into play as well. In addition to our quantitative tests, we recorded our impressions while using each model to keep laptops and phones running through at least one workday.
Our pick for most people
For anyone looking for a portable power source to charge a laptop or other small electronics that get power from a standard AC outlet, the ChargeTech Portable Power Outlet (27 Ah) offers the best combination of size and capacity, and is useful enough to justify its price.
The ChargeTech has a roughly 97 watt-hour (Wh) capacity—that’s enough to charge most midsize laptops once or twice. For comparison, a 13-inch MacBook Air carries a battery of around 40 watt-hours, our favorite Chromebook has a 45 watt-hour battery, and our favorite gaming laptop has a 66 watt-hour battery. The Goal Zero Sherpa 100 with the Sherpa Inverter attachment has an almost identical capacity rating but costs twice as much. At other end of the price range, the Xcellon PB-1200AC offers about 40 percent of the power of the ChargeTech for 60 percent of the price. That isn’t a huge difference in cost per watt-hour of capacity, but the PB-1200AC’s roughly 43 watt-hour capacity is so small that it just doesn’t seem worth buying for half a laptop charge.
Estimating the number of times one battery can charge another is relatively easy: You just divide the capacity of one by the other. But if you’re looking to power something directly, such as lights, fans, or TVs, you need to know the wattage of the device to be powered—unlike capacity, which is a cumulative measurement, wattage is an instantaneous measurement, similar to a car’s speed versus how far it can drive at that speed. And just as a car going 50 mph for one hour will go 50 miles, a 50-watt television running for one hour will use 50 watts × 1 hour = 50 watt-hours. Because the ChargeTech offers a 97 watt-hour capacity, it should have enough energy to keep a 50-watt TV going for almost two hours. But that’s just the math. In our real-world tests, we expected (and measured) about 75 to 80 percent of the calculated capacity for all the models we tried. One reason for this result is that advertised ratings are based on a battery’s maximum potential, but it’s fundamentally impossible to drain all the energy from a battery like that. (We generally expect discharged capacity to be 90 to 95 percent of advertised capacity.) Another reason is that the small, inexpensive inverters inside these batteries aren’t particularly efficient—when they convert DC battery energy into standard AC power, they lose around 10 percent of the capacity.
No tiny inverter can power a high-draw device like a refrigerator or large plasma TV, but with a claimed maximum output of 90 watts, the ChargeTech should handle any laptop, battery charger, or other small electronics without a problem—you could even run a fair-size LED TV in a pinch. In contrast, the Sherpa Inverter from Goal Zero is rated at only 75 watts, and the Xcellon, rated at just 65 watts, will have trouble with bigger or older laptops.
Because the ChargeTech is about the size of a small hardcover book, and a similar weight, it’s compact enough for you to carry it in your bag whenever you’re out with your laptop. The Xcellon is noticeably smaller, to the point that you could carry it with you all the time “just in case”—but with only 40 percent of the ChargeTech’s capacity, it doesn’t seem worthwhile. Meanwhile, the Goal Zero Sherpa 100 feels heftier, to the point that we’d carry it only if we were really sure we’d need it. That extra heft is due in part to the fact that the Sherpa 100 is the only model with fans to keep it cool. Fans are a catch-22 for manufacturers: Although the ChargeTech and Xcellon both got uncomfortably hot in our tests, the Sherpa 100’s fans added weight and were so loud that using the battery was conspicuous in quiet settings—you’d definitely be the loudest person in a library or lecture hall.
Capacity, output, and some amount of heat and noise are all trade-offs involved in using one of these batteries. For a real-world test, we tried to power an aging 2012 11-inch MacBook Air (with a battery that can hold only around 22 watt-hours of its original 39 watt-hour maximum) through a Wirecutter workday on portable power alone. When we started the day with the MacBook fully charged, the ChargeTech gave us a second full charge midday and had a little to spare for the evening, too. For comparison, we also performed a test with each battery in which we plugged the Air, with less than 5 percent charge, into the fully charged pack. As we used a steady mix of two Web browsers, an email client, Slack, Messages, and iTunes, the ChargeTech kept the MacBook running while it charged the computer’s battery to 100 percent, leaving the ChargeTech with about a third of its own capacity remaining. The Goal Zero Sherpa 100 is rated for roughly the same capacity as the ChargeTech, so we weren’t surprised to see that model perform almost identically: It charged the MacBook to 100 percent, with a bit over 20 percent of its own battery left. The Xcellon PB-1200AC, in contrast, shut down after filling the MacBook just halfway.
Flaws but not dealbreakers
Although the ChargeTech Portable Power Outlet (27 Ah) offers the best value in its size category, it has a few drawbacks. In our tests, both it and the Xcellon got noticeably hot in use, whether charging or discharging. This result isn’t surprising, because inefficient inverters often lose power to heat, but the battery gets warm enough that we wouldn’t leave it unattended, just to be on the safe side.
The build quality of the Portable Power Outlet feels on a par with that of your average battery pack, charger, or portable hard drive—it isn’t amazing, but it isn’t flimsy, either. ChargeTech warranties the Portable Power Outlet for a year, with support available mainly through email.
The matte-black finish of our “special edition” review unit—the casing and box appear to be the only things different from the standard editions—is prone to fingerprints, oils, and scuffs. None of the ports have reliable protection from debris: The USB ports aren’t covered at all, and though the AC outlet comes with a small cover, that piece isn’t attached in any way—unless you’re judicious about such things, just plan to lose the cover the first time out. Even some basic protections here would make the ChargeTech as competent at a campsite as it is in a café.
The device charges via a small DC port and an included charger, a cable with a soap-bar-size power brick in the middle. If future versions were to take advantage of a high-power USB charging spec, that would eliminate the power brick and the need to carry a proprietary charger, as you could use any standard USB charger you might already be traveling with.
These are all nitpicks, to be sure, but in a battery priced around $185 at this writing, they’re much more annoying and obvious than in an accessory costing a quarter of the price. But even with its flaws, the ChargeTech Portable Power Outlet is the most convenient and affordable tool for the job.
When you need more power
If you’re looking for more oomph, the Goal Zero Yeti 400 Solar Generator should do the trick—as long as you don’t need to carry its 30 pounds very far, that is. Newer, more compact competitors have been introduced recently, but the Yeti 400 has three years under its belt and remains a good value with a reputation for reliability. In our tests, it offered four times the available power of our smaller pick (the ChargeTech Portable Power Outlet), but it costs only about twice as much at this writing. With that much power, the Yeti 400 can charge a 13-inch laptop a handful of times or keep a 75-watt television going for almost four hours.
The Yeti 400’s reliance on older, lead-acid battery technology is the reason behind the model’s biggest upside, more-affordable capacity—but it’s also the reason for the product’s biggest downside, considerable weight. The lead-acid battery is pretty similar to what you have in your car, and the basic technology has been around a long time. It’s reliable and affordable, but the “lead” part is no joke—it’s freaking heavy. The Yeti 400 is a stout little box (10 by 8 by 8 inches) that easily fits in a plastic milk crate; each time we lifted it, we were surprised by just how heavy it was. (Thankfully, it has a sturdy, extendable handle on top.)
The Anker PowerHouse, which offers similar capacity at a similar price, is about a third of the weight of the Yeti 400 thanks to its use of lithium battery cells. That weight difference seems compelling at first, but 10 pounds is already too heavy for most backpacks, and the PowerHouse is still too bulky to lug around in a day bag—we wonder how many people would take a 10-pound battery anywhere that they wouldn’t bring a 30-pound battery. When spending $400 or more for a giant battery, longevity is definitely a factor. Goal Zero made a smart decision here, as the lead-acid battery inside the Yeti is user-replaceable and not prohibitively expensive—a branded replacement costs $100, and a comparable generic is available for around $65. The same can’t be said of the PowerHouse, which is a completely sealed unit. If the battery fails to hold a charge after a couple hours, the only options are sending it back to pay for a repair or replacement—assuming Anker continues to support the device—or to recycle it and start over. We know that engineering swappable lithium battery packs can be a challenge due to extra power management circuitry required, but it’s a challenge that Goal Zero has promised to overcome in the lithium versions of the Yeti lineup due out later in 2017. Hopefully the next version of the PowerHouse will follow suit.
Aside from the battery, the other main feature of a portable AC power source is the inverter—how much power it can provide, and the quality of that power. Though the Yeti 400’s large battery has pros and cons, the savings the company achieves by using older battery technology gets you a much better inverter than what’s available in our smaller pick: The ChargeTech Portable Power Outlet can provide just 90 watts at any given moment, but the Yeti 400 can power up to 300 watts continuously, and it has a 600-watt surge capacity. Thanks to its extra power, the Yeti 400 can also offer a second outlet and easily power two computers at the same time, or manage lights, fans, or battery chargers without problem. The Anker PowerHouse can output only 200 watts at a time and is limited to a single AC outlet. Though that won’t be a problem for less-rigorous uses, it limits the versatility.
Despite the difference in output, both the PowerHouse and the Yeti do use higher-quality pure-sine-wave inverters compared with the cheaper modified-sine-wave inverters in smaller units like our Chargetech pick. That may sound technical, but what it means is that instead of rougher power that a small fraction of devices won’t handle well, these better inverters produce smoother power that any device can handle—power that’s just like what the utility companies send out to standard wall outlets. Most of the time, rougher power doesn’t make a big difference, but some devices will have side effects from modified-sine-wave inverters: Audio equipment may buzz, chargers may not work as efficiently, motors may not maintain consistent speeds, and some power supplies may get warmer than normal.
Because each claims to have high-quality inverters, we took a look at the power quality of both units using BitScope DSO software and a BitScope Micro Oscilloscope and Analyzer that Bitscope provided for testing. Both portable power units put out pure-sine-wave power as promised, and neither will cause any problems with even the most sensitive electronics. That said, Anker’s inverter does create a bit more noise in the waveform than the inverter in the Yeti. It shouldn’t make a practical difference, but this could point to Goal Zero using slightly higher-quality components or designs in order to get cleaner power output.
The Yeti 400 also offers some additional features that you won’t find in smaller devices. Along with its two AC outlets and two USB ports (capable of up to 2.7 amperes each or 3.5 amperes combined in our tests), the Yeti 400 includes three DC-output ports. Goal Zero also sells vehicle and solar chargers for the unit. Though the vehicle charger would be handy on long road trips, the solar charger doesn’t seem practical unless you have no other option: The company says that its 30-watt Boulder solar panel would take 26 to 52 hours to completely recharge the Yeti 400. For a serious (and less mobile) investment, you could chain several panels together to speed things up, but we think most people will end up just charging at home and budgeting their power while on the go. (That goes for other high-output, portable solar products as well. The integrated 20-watt panels in the Renogy Firefly, for example, seem much more convenient than separate external panels, but even with the much smaller battery, Renogy estimates that a complete recharge will take 9½ hours—you should assume that amounts to two days’ worth of sun. Anker has promised solar accessories for its PowerHouse unit, but no details were available at the time of this writing.)
Large sources of portable AC power have their place for road warriors, car campers, or anyone who works on location or in the field, and the Goal Zero Yeti 400 Solar Generator currently occupies the sweet spot between small battery packs like the ChargeTech Portable Power Outlet and large gas generators.
What to look forward to
We plan to test several large units, including Renogy’s Lycan Powerbox and Firefly, Jackery’s Power Pro, and a few other upcoming models, to find out how they stack up against the Goal Zero Yeti 400. EnerPlex released the Generatr S100 while we were testing; we’ll also look into that model for a future update.
Goal Zero recently released a lithium-based version of our more-power pick. This new Yeti 400 is around 30 percent smaller and lighter than the lead-acid model and could open the door to more scenarios where portability is important. But the shift to new batteries and a more-advanced inverter almost doubles the pricing. We’re looking into testing the lithium version, but we think it’ll be a few years before the technology is no longer cost-prohibitive for most people.
The Anker PowerHouse offers a credible alternative to the Goal Zero Yeti 400, but falls short in just a few ways. Though the lighter weight (about 10 pounds) and smaller size (6.7 by 7.9 by 6.5 inches) are both welcome reductions, the PowerHouse is still too big and too heavy to comfortably carry in a backpack, so campers will probably want to stick with car camping. And though it offered almost 30 percent more available capacity than the Yeti in our tests, the maximum power output is also about 30 percent lower, making the PowerHouse less versatile for high-power uses, including small appliances or lighting equipment. It’s a difference highlighted by PowerHouse’s single AC outlet, compared with the two outlets on the Goal Zero. And though the PowerHouse’s lithium cells should have a slightly longer life span than the lead-acid battery inside the Yeti, the PowerHouse is a sealed unit with no user-replaceable parts. That means that when the battery capacity starts to degrade, your only option is to recycle the entire unit, or send it back to Anker for a replacement.
RAVPower came out swinging this fall, releasing two battery packs with AC outlets, the RAVPower AC Portable Charger 27000mAh and the RAVPower AC Portable Charger 20100mAh. The larger of the two competes directly with our pick, the Portable Power Outlet from ChargeTech, as it offers the same 98 watt-hours of power, a single AC outlet, and two USB ports. It adds a USB-C port, but that component is for power output only—the pack still requires you to recharge it with a cumbersome power brick jacked into a DC port. But even though the features and price make this model competitive with the ChargeTech unit, RAVPower let a major dealbreaker slip into the design: Instead of including a three-prong outlet, the charger has only has a two-prong outlet. This design decision makes sense from a safety and engineering standpoint—the ChargeTech and any other portable power sources are obviously not grounded, and the third slot is really just a dummy port—but it makes the RAVPower 27000mAh charger unusable for any laptop with a three-prong power cord. That affects a good chunk of PC laptops, as well as any Apple laptop that has an attached cord extension. RAVPower recognized this and began sending adapters to existing customers who requested them—and including adapters in future orders—but even so, no one wants an extra adapter in their bag when other options don’t require one.
The smaller new charger from RAVPower, the AC Portable Charger 20100mAh, offers some welcome variety, as it’s roughly the size and dimensions of a 14-ounce coffee cup from a café. It fits well in a large cup holder, or in the water-bottle pocket of a backpack. Though it holds about 25 percent less energy than our pick from ChargeTech, it’s also about 40 percent cheaper. In reality, the capacity (72 Wh) and output (70 W) are still plenty to charge most laptops—and to charge smaller ones twice. Like its big sibling, it also has a USB-C port, though again frustratingly only for power output; you’ll need to lug the wall adapter and power brick with you to charge it back up. It also has the same dealbreaking two-pronged outlet as the bigger model does. Even though RAVPower included a third slot on the outlet, it isn’t actually a US-standard shape. It looks close, but the grounding prong slot is just ⅛ inch too far away from the other slots to fit a standard grounded plug. It’s a maddening flaw. Even if that were to be corrected, the flap that covers the outlet hinges in a way that prevents large power adapters from sitting flush in the outlet. We’ll be looking forward to version 2.0, but until then our picks are still the best options.
The Xcellon PB-1200AC 12,000mAh Power Bank with AC and USB Outlets has many similarities to our pick from ChargeTech, but overall it doesn’t offer as good a value in terms of capacity per dollar. In tests it filled our small laptop only roughly halfway during use, in contrast to the full charge and then some that the ChargeTech Portable Power Outlet provided. Though the ChargeTech costs more, that model’s added capacity makes it more flexible and therefore more valuable to carry than the Xcellon unit. But the other commonalities may make the Xcellon a good buy if the ChargeTech is too expensive for you. Interestingly, when we compared the build quality of the PB-1200AC against that of our Portable Power Outlet unit, we noticed enough similarities to suspect that they came from the same factory. All of the Xcellon’s component parts—the buttons, switches, outlets, and casing—seem to be from the same materials as the ChargeTech’s corresponding parts. Aside from the labeling, even the power adapters are the same. (We asked Gradus Group, the company that makes the PB-1200AC, if the battery shared any manufacturing processes with the ChargeTech Portable Power Outlet, but the representative told us that the company does not disclose manufacturing locations.)
Though the component parts and waveforms of the two devices looked similar in our analysis, we couldn’t explain some strange MacBook behavior after powering the laptop with the Xcellon model. After the PB-1200AC brought our test 11-inch MacBook Air to a 53 percent charge (according to the computer’s battery meter), the MacBook ran for only about 40 minutes or so. That’s half of the time the computer normally lasts with half a charge, but we weren’t able to determine why this happened—the problem could be related to the MacBook’s battery meter rather than to the battery pack itself.
The Goal Zero Sherpa 100 Power Pack with the Sherpa Inverter attachment was hands down the most well-constructed device of those we tested, but it seems a bit dated in a few ways, not the least of which is its big price tag: At its current price of $400, the Sherpa 100 doesn’t reflect the dropping costs of lithium batteries since the line’s initial release in 2010, or the Sherpa 100’s release in 2013. And though the Sherpa 100’s internal fan helped to keep it cooler than the other two models we tested, it’s incredibly loud. You don’t want the fan to start up in a quiet room, because it will be noticed. Add to that a slight electronic whine due to the type of inverter Goal Zero uses in the Sherpa 100, and this device could ruin a quiet day in the library or a silent night in the woods. If Goal Zero were to drop the price to match the hardware, or upgrade the hardware to match the price, it would be a much more compelling option.
Even though the Sherpa line feels dated, the Goal Zero Yeti products are a solid choice, assuming you really need the power and you don’t object to the extra weight. The Yeti 400 is our larger-model pick because the other two sizes in the line—the Yeti 150 and the Yeti 1250—won’t hit the sweet spot for as many people. The Yeti 150, offering 150 watt-hours of energy capacity, costs a little more than our top pick from ChargeTech but isn’t nearly as portable. And like the 10-pound Anker PowerHouse, the 12-pound Yeti 150 is too heavy for a carry-on or backpack, so you might as well move up to the 30-pound Yeti 400. At the other end of the spectrum is the Yeti 1250, which costs $1,600 at the moment; with a price tag that large and 100 pounds of heft, it isn’t a practical option for anyone but professionals.