Matravers School cookery competition

The Power Of The Human Jaw

ATEN-POUND bite requires a forty-pound contraction of the human jaw muscles. That is because the jaws are built on the principle of a pair of tongs, The power is applied near the joint, while the work is performed at the opposite extremity of the jaw levers. Had a mechanical engineer designed the human frame, he would no doubt have built the jaws after the fashion of a nut cracker, with the muscles placed at the ends of the jaw levers, and the teeth between these ends and the joint or fulcrum, so that a powerful bite could be obtained with a very small expenditure of muscular effort. However, in the physiology of man and all other animal life, for that matter, mechanical advantage weighs for little in the presence of other broader considerations. This is why nearly all the principal muscles of the body must be far more powerful than would be necessary were they to act directly upon the work. When chewing we have an almost direct application of the power of the muscles, as they nearly overlie the third molars. There is a vast difference between chewing and biting. In order to determine the average strength of the jaws, Dr. G. E. Black, president of the Chicago Dental University, some time ago devised an instrument of very simple design but with a name that would put the average jaw to a severe test the gnathodynamometer. With this instrument he made gnathody-namometric tests of the jaws of a thousand persons. They were selected at random, and probably represent a good average of civilized people. He found that the limit of the bite was not determined by the muscles, but by the teeth themselves. In nearly every case, the patient would cease his efforts, owing to the fact that his teeth hurt. This would depend largely upon the condition of the peridental membranes, and upon the habits of the patient in accustoming his teeth more or less to chewing hard foods. The average of the thousand persons showed 171 pounds for the molar teeth and much less for bicuspids and incisors. Out of the one thousand persons, seventeen developed a force equal to the full registry of the instrument, which was 275 pounds. In a recent publication, Dr.. Black has tabulated the records of about fifty persons who were tested with the gnathodynamometer. The list includes men and women of all classes, from a blacksmith to a Chinese laundryman, and from a servant girl to a. Music teacher. It is natural to picture a butcher as a man with a well-developed and powerful jaw, hut among the patients in the list, the butcher showed a power of only 165 pounds with his molars, from which we may infer that he is accustomed to selecting' tender meats for use on his own table. The man with the highest record was a printer who registered 270 pounds; (but any compositor will admit that printers' pie is tough) while the second honors went to a dentist with 240 pounds. Among the women the highest record reached was 160 pounds, while the lowest was 45. Strangely enough, the schoolgirl who made the latter record was able to register 70 pounds with her incisors, which might indicate that she had accustomed her dental membranes of the front teeth to harder work by biting a pencil, or something of the sort. At any rate she was one of those unfortunates who "bite off more than they can chew." In this list of records, males showed an average of 150 pounds with the molars and 83 with incisors, and females 108 pounds with the molars and 57 with incisors. The instrument with which these records were made comprises a pair of steel arms, which are normally spread apart by spring tension.' Each arm is equipped with a rubber pad, on which the biting is done. When the patient bites the pads, the levers are forced toward each other and cause an index needle to travel over a graduated arc which shows the force of the bite in pounds. One of the difficulties that had to be contended with was that the full power of the muscles cannot be exerted until the jaws are nearly closed. This made it necessary to reduce the biting pads to a minimum compatible with safety. In selecting patients whose jaw muscles were to be tested, it was imperative that the teeth be examined for any indications of decay which would weaken them to such an extent as to cause injury when biting on the in- strument. In addition to the gnathodynamometer, Dr. Black has invented another instrument with an equally terrifying name — the phagodynamometer, with which he tests the resistance to chewing offered by various foods. This instrument comprises a pair of plungers with toothed surfaces at their adjacent ends. By means of a lever one of the plungers is forced against the other. The latter acts upon a spring, connected with an index needle arranged to sweep over a dial. The pressure of one plunger upon the other plunger may then be read on this dial. With this instrument, some important studies have been made of the force required in the mastication of food. These are shown graphically at the top of this page. In place of muscles the jaw is represented as being provided with a scale beam and a 10-pound sliding weight on the beam. If the weight be moved to the point marked 50, a fifty-pound crushing force will be exerted at the second molars. The tenderest meat was found to be boiled tongue, the central part of which offered a re- Rear vjew 0f the device. Sistance of from three to five pounds. Boiled tongue, when cold, offered a resistance of from fifteen to twenty pounds. In order to crush pork chops, loin, a force of from twenty to twenty-five pounds was necessary. Mutton chops required from thirty to forty pounds; beef, round, from forty to fifty, and beefsteak, well done but rather tough, from sixty to eighty pounds. An experienced butcher selected some very tough meats, from the neck of an old animal, which stood up against a force of from seventy to ninety pounds before the crush occurred. These tests were made a number of years ago, before storage meat was used to the extent it is now. The figures should be reduced about one-third for meat made tender by storage. With these data, the mathematically inclined may proceed to figure out the horse-power developed at the boarding-house table. A surprising fact brought out by the use of the phagodynamometer is that the hardness of food does not determine its danger to the teeth. For instance, candies that are quite hard offer much less danger to the teeth than gum drops, which ordinarily are mashed out of shape at from twenty to thirty pounds. If part of the gum drop became wedged between the cusps of the teeth, it was found that frequently it could not be completely crushed with a pressure of less than 250 pounds. Sticks of licorice proved particularly dangerous in this way. But the most remarkable discovery was that even bread might cause the breaking of a cusp. To quote Dr. Black, "With my personal observation, more teeth that seem sufficiently strong have been broken with bread crusts, and not very hard crusts either, than with any other one thing. I used sometimes to feel that persons relating these accidents were not quite honest in their statements, but when I tried the bread and found that it would wedge in between the cusps of the teeth, and not be crushed out with a force of 350 pounds, I changed my mind,"

This article was originally published with the title "The Power of the Human Jaw" in Scientific American 105, 23, 493 (December 1911)

doi:10.1038/scientificamerican12021911-493

Top 10 Best UFC Southpaws Of All Time, Ranked

Coming in as my number one southpaw is easily one of the most underrated fighters in MMA history, Yves Edwards.

Yves Edwards is one of the most underrated fighters in MMA history.

Savvy southpaw striker, introduced devastating clinch tactics to UFC before Anderson Silva, beautiful counters, wrist controls, kimura traps… this guy did it all.

FULL CAREER HIGHLIGHT: https://t.Co/Zv2I4WN0qO pic.Twitter.Com/N0uWGerdn6

— Dan Tom (@DanTomMMA) June 27, 2023

Aside from the fact that Edwards was executing Demetrious Johnson-level clinch knees on the HOOKnSHOOT circuit all the way back in 1999, there was a point in time when the "Thugjitsu Master" was considered the best lightweight in the world.

As many hardcores know, the UFC has traditionally mistreated the lighter weight classes on its proverbial totem pole – particularly the lightweight division. And after multiple failed attempts that saw them lose a sitting champion in Jens Pulver and a star-in-the-making with B.J. Penn, the UFC seemingly had little enthusiasm in putting another belt up for grabs when Edwards collided with Josh Thomson back at UFC 47.

Despite not getting his flowers as one of the best lightweights on the planet, Edwards still went out and provided one of the greatest highlights of all time en route to what should've been the biggest victory of his career.

📆 #OnThisDay in 2004 – Yves Edwards landed this UNBELIEVABLE headkick!

Watch more insane KOs ➡️ Only on @UFCFightPass! Pic.Twitter.Com/yScL576cTi

— UFC (@ufc) August 21, 2020

Edwards would continue to take on top talent around the world and took some tough losses as a result, but still managed to produce many inspiring moments late into his career.

From checking leg kicks to building off of bodywork, watching a young Edwards operate was like looking into the future. The man was ahead of his time and inspired so many of your favorite fighters, including Dustin Poirier (who Bruce Buffer still introduces as a "Thugjitsu fighter").

For me, the most important punch for a southpaw to master is the check right hook – and I don't think anyone will have a more masterful example of one than Edwards.

I miss watching Yves Edwards work. One of the most technical southpaws in the game who set traps (as well as examples), especially when it came to my favorite punch: the check-hook pic.Twitter.Com/FlCRzOFie4

— Dan Tom (@DanTomMMA) January 6, 2018

*Honorable mentions: Lyoto Machida, Tim Means, Jens Pulver, Michael Johnson, Benson Henderson, Rick Story, Kenny Florian, Chris Curtis, Vitor Belfort, Nick Diaz, Nathan Diaz, Islam Makhachev, Johny Hendricks

Best Portable Power Stations For June 2023

$1,099 at Anker

Anker 757 PowerHouse

Best portable power station for backup

Show more (1 item) In this article:

As electronic devices become ever more integrated into our daily lives, the need to keep those devices powered and online increases. But we can't bring the power grid with us wherever we go. Portable power stations are the perfect solution to keep us... Well, portably powered. There are enough bells and whistles these days to justify adding one of these to your normally powered life as well.   

If you're looking to juice up your devices, your options are no longer limited to bulky, simple power banks with basic outlets. Major improvements have been made to portable power stations since we first started reviewing them here at CNET. As the industry has matured, it's brought even more portable power station options. Many of these include features like USB ports, solar panel inputs and wireless charging. You can even daisy-chain some models for even more power, or connect them to your home's electrical system, giving you backup power in an emergency or power outage. 

Chris Monroe/CNET

Gas-powered generators were your main option for "off-grid" power where electricity is needed, especially in more temporary situations like camping if you didn't have an RV or another power supply for your campsite. 

I put each power station through its paces and considered factors such as battery life, power output and input charging options as well as output options for juicing up my gear. (Power stations that only sport AC outlets and forcing you to use adapters are no longer viable.) Each is more than just an on-the-go phone battery charger or glamping must-have. These power bank performers have wide-ranging uses from building and construction to staying connected with the office or family to having access to emergency lighting and power wherever you roam or call home. 

This was the toughest category to pick. The Jackery Explorer 240 and Bluetti EB3A were also top contenders, and they both cost less than the Togo model. Nifty features and an extra 40%-plus battery capacity give the slightest edge to Togo.

There were two main features that made the difference for me. All three units have an AC plug, 12-volt socket and USB-A connections for devices. But Jackery doesn't offer a USB-C connection. Additionally, Togo was one of the few units overall to offer wireless charging. (The Bluetti EB3A also has this.)

Togo also showed us the largest measured capacity percentage compared to its stated capacity at 346 watt-hours at 98.95%. This unit isn't particularly fast to charge, however, taking 4 hours, 17 minutes to fully charge from empty.

The Bluetti 50S comes in as the second lowest "price per watt-hour" metric I've tested to date. When looking at the feature list, that is enough to get you "best value" in this product space. 

As well, the 50S also captures our best midsize portable power station title. The midsize portable power station category is a crowded space and there are a few nearly equal alternatives to the 50S like the Ecoflow River Max or the Oupes and BioLite models. 

You're getting all the input-output charging options you could ask for, including what seems to be the new industry standard of compatibility with solar panels for charging. This one does take a bit longer to charge than some of its siblings. Seven hours to full compared to just under five hours for the Bluetti AC200P which offers four times the battery capacity, or the similarly sized Bluetti EB55 (537Wh compared to 500Wh from the 50S) which can achieve 0-100% charge in about three hours. 

Bluetti does tend to put wireless charging into most of their devices, and that's a personal favorite feature of mine. The 50S has one, as well as another must-have feature for me -- a USB-C port. I'd like for it to have more than the one port, but considering many units still are limited to USB-A, I'll take what I can get. 

The previous title-holder (Bluetti AC200P) weighed in at just over 60 pounds, and was not for the faint of heart or weak of arm. The Anker PowerHouse 767 is even heaver (7.4 pounds more!) with a major difference that makes that weight a bit more bearable -- literally. The 767 is built on wheels and even has a suitcase-style retractable towing handle. You'll still have to lift it on or into vehicles our countertops, but when you're moving from place to place, this makes the task much more accessible. The 767 body is also reportedly impact-resistant, shock-proof, anti-UV and flame retardant. Could be fun to test -- but I'll take their word on it. For now. 

It sports a LiFePO4 battery for over 3,000 charge cycles. Charge it with up to 1,000 watts of solar power. Tons of output options (three USB-C ports!) and the only one missing in my opinion is a wireless charging base. I suppose there are enough other options to connect a wireless charging pad if you really wanted. 

Another often overlooked aspect of portable power stations is the output wattage and power rating. This is different from the continuous power rating (in watts) for each unit. For example, the 767 boasts a maximum  2,400-watt output power rating. That means, if you wanted to connect several LED lights that were each rated at 200-watt power output, you could expect to be able to run twelve of those simultaneously. When LED lights are turned on, generally, they don't require any "extra" power to get going. 

The Powerhouse 757 is a solid, sturdy machine (our second heaviest one at nearly 44 pounds). It's a great pick among the over-1,000Wh choices, and really only missed out on winning the large power station category due to some extra bells and whistles other units in that category have. But there are a couple of notable features Anker's put into this unit that give it the gas to dominate this category. 

For starters, the battery itself is the newer LiFePO4 makeup, compared to the more common Li-ion batteries. This newer battery type can be safer to use and can last five to six times longer than the Li-ion ones. This means that compared to the current standard of a 500-cycle lifespan, LiFePO4-donned units could run 3,000 cycles or more. This gives Anker the opportunity to offer a five-year warranty compared to the two-year warranty of many competing units.

Next, many of the current-gen power stations are coming with a "UPS Mode" to offer backup power to critical pieces of equipment during power failures. You plug the power station into your wall outlet and the equipment in question into your power station. With UPS mode enabled, the power station will kick in and power whatever is plugged into it from its internal battery. But before you run out and replace your existing UPS units with one of these, you should know that it is almost the same as a UPS. But not entirely.

A dedicated UPS could have a transfer time (the amount of time it takes for its battery to take over one the grid power has failed) of anywhere from 0 milliseconds to 12ms, and most of them try to stay at 8ms or faster. Anker states a transfer time of "less than 20ms." That's great as far as portable power stations go. But as a dedicated UPS that you might want protecting a core piece of tech or important medical device, you might consider a different solution. But by all means, your TVs, laptops, fridges and other devices will be well looked after.

By camping, I don't mean "glamping." I'm not trying to power your PS5, beer fridge and jacuzzi. Since solar panels are more common now, and most every portable power station offers an option to charge with them, we don't have to be quite as concerned about overall battery capacity or our ability to get to grid power to recharge. 

Even if it does carry a hefty price tag (though it's often on sale for less than its normal retail price of $999), I feel like this model hits a sweet spot of basic functionality, capacity and price. Even though you have the option of charging via solar panels, you can probably survive a weekend trip with a full charge -- obviously depending on what you're powering. And that helps when you're in sub-prime conditions for solar charging such as overcast or rainy days. 

You have plenty of output options, lots of AC ports and at just under 24 pounds, this unit isn't too heavy to cart around or move-as-needed during your outing.

If you happen to be a solo flier, or otherwise have very minimal electrical needs when you camp, check out the Jackery Explorer 240. It offers all the basic needs, reliable construction and also happens to be the cheapest power station on our list. 

It's also worth mentioning that even though the GoSun PowerBank 1100 didn't finish in the top of our testing, GoSun offers a whole suite of camping and solar-friendly equipment, including a nifty folding solar table that I'm hoping to add to an upcoming solar panel best list.

I like the Jackery line of portable power stations. I would still like to see wireless charging in a Jackery battery, but otherwise, the Jackery Explorer 2000 Pro checks a lot of boxes, not least of which is charge time. 

We run all of our portable power station charge tests using AC power, and based on those results, this Jackery is blazing fast when it comes to charge time. Jackery claims 2,160Wh for this unit, and our tests show that it can go from completely dead to 100% in 117 minutes. There are only a handful of units we've tested overall that can charge faster than that, and most of those boast half the capacity. 

The great thing is, if you're really in a pinch, you could attach your six Jackery SolarSaga 200 solar panels for 1,200 additional solar charging watts and nearly cut that time in half (the 2000 Pro offers a max of 1,400 input watts for solar charging -- also the largest we've tested to date). 

If you plan on draining your capacity super fast, and you'd like to recharge ASAP via AC, solar or both, (even while you're draining it) the Jackery Explorer 2000 Pro should be your first choice.

Other portable power stations we've tested

Energizer PPS700 (626Wh): OK performance and features overall, but one of the lowest tested capacities, making the usable capacity closer to 477Wh.

EcoFlow River Max (576Wh): Blazing fast charging and a low cost per watt-hour make this a reasonable pick, however this unit did test lowest in measured vs expected capacity, putting it at 425 usable watt-hours. Where'd those extra 151 watt-hours go?

Speedwatt (298Wh): Just kind of OK. Capacity is good, but we tested two separate units and both seemed to have some disconnect between the actual performance of the unit and the information displayed on the user screen. Currently listed as unavailable. 

GoSun PowerBank 1100 (1,100Wh): I really wanted to like this unit more, partially because of GoSun's extended offerings of solar-friendly devices, and as far as capacity goes, this runs in the middle of the pack, but man is it slow to charge. It took nearly 12 hours -- over six times as long as our largest power station (Jackery Explorer 2000 Pro) that offers nearly twice the capacity. At $1,299, I'd like to see a faster charging option and maybe more outputs or at least wireless charging.

Bluetti EB55 (537Wh): We've liked most every unit from Bluetti, and three of them took titles in this best list, but this unit just got overshadowed by its siblings. Just as good or better offerings at better prices keep the EB55 out of the winner's circle.

Fanttik Evo 300 (299Wh): This is a solid pick in the small power station category. And this unit sports my favorite display -- extra large and easy to read. Average performances on our charging and capacity tests.

BigBlue Cellpowa 500 (537.6Wh): This is a better-than-average performing unit at better-than-average pricing. Nothing outstanding to speak of. 

Jackery Explorer 240 (240Wh): We've been fans of all the Jackery units we've ever tested in the past, and that doesn't change here. Just missing the best small power station title, this unit still boasts the second best capacity rating of all the ones we tested. A little slow to charge, but a great price.

Generark HomePower One (1,002Wh): This unit was the second slowest overall to charge, but did well on its usable capacity rating at 91%. Its display is small, but offers all the standard input and output features you'd want.

Oupes 600W (595Wh): Not a bad little unit -- not a great one, but definitely not bad. I love that it has the LiFePO4 battery. It performed about average (maybe a hair under par) and I feel like it could be cheaper. Also, how do you pronounce that name? "Oops" is the current best guess.

Goal Zero Yeti 200X:: The Goal Zero products are pretty solidly made, but we did get the lowest score in our 'usable capacity' tests from this unit -- about 65% compared to the industry-accepted norm of 85%. There are better products in the small portable power station category. 

Rockpals 300W: This unit also came in under the line in usable capacity. Given the industry standard of 85%, Rockpals' 78% is a bit lacking. In terms of charge speed, this unit is one of the faster small portable power stations. Decent features -- kind of looks like a handheld radio. 

BioLite BaseCharge 600 (622Wh): Here's a unit that's totally ok with a totally ok price. 87% usable capacity, Li-ion battery, average features, maybe a little slow on the charge time. But hey -- it does have wireless charging! 

Jackery Explorer 1000 Pro (1,002Wh): The 1000 Pro falls into our large portable power station (begins at 1,000Wh -- this Jackery weighs in at 1,002Wh), same as its big brother the 2000 Pro. I like the 2000 for several reasons more than the 1000, so the 1000 never really had a shot at taking the 'large' category. But still, good performance, nice features and pretty amazing charge times. Can't go wrong.

Anker 555 PowerHouse (1024Wh): More and more portable power stations are shipping with LiFePO4 batteries and I love that. The 555 is slower to charge than most of its competitors, but sports a 94% usable capacity and an attractive price point vs number of watt-hours. All the better to power those six AC outlets!

EcoFlow Delta 2 (1024Wh): The EcoFlow Delta 2 is very similar to the Anker 555 PowerHouse across the board -- features, pricing, etc. The main differences you can see from our tests are the usable capacity percentages: Anker with 94% versus EcoFlow with about 70% and charging rates -- both being rated at 1,024Wh. The EcoFlow Delta 2 charged to full in only 86 minutes, 275 minutes faster than the Anker model. Another cool point for EF with having the capability to wire in a secondary battery module, taking the capacity from 1,024Wh to 2,048Wh. Expect to pay an additional $800 for that battery expansion. 

Geneverse HomePower One Pro (1,210Wh): This is the grownup version of the Geneverse HomePower One. The feature specs are about the same, but at $500 more, you're only getting about 200 extra watt-hours. As well, the standard One model comes in at 91% usable capacity versus the Pro model's 73%. That gives you 912.6 usable watt-hours with the standard and only 886.7Wh on the Pro. The Pro did however charge in almost a quarter the time it took the standard version. 

BioLite BaseCharge 1500 (1,521Wh): Having tested both the 600 and 1500 models of the BioLite BaseCharge, I can tell you that this company is fairly consistent when it comes to their product manufacturing. The BaseCharge is about 2.5 times the capacity of the 600. And that 2.5 modifier carries across the board fairly accurately from price to capacity, charge times, everything. So, if you like the 600 but you wish you had two-and-a-half of them, save yourself the effort and just buy the 1500.

Renogy Phoenix 200 (189Wh): Slower to charge, but a whopping 96% usable battery capacity paired with the lowest price of any unit we've tested, makes this a great option for smaller use cases or generally for people interested in checking out portable power stations without breaking the bank. 

Zendure SuperBase Pro 2000 (2,096Wh): The first unit we've tested with the Li-NMC battery composition. This unit also just missed the best large portable power station title. It does have a weight-to-capacity ratio likely thanks to the NMC composition, and boasts  our highest solar charging capacity to date at 2,400 watts. It's telescoping handle and wheels do make it easier to manage, but the form makes it a little more compatible navigating paved walkways versus 'off-road' terrain. 

Runhood Rallye 600 (648Wh): There are a couple of these types of units on the market now, and I've been waiting for their arrival. This Runhood unit is the first modular style portable power station I've been able to get my hands on, and I love what it means for the industry. Performance-wise this thing was about average, but it could offer you more in flexibility and convenience than many other units. The batteries are swappable, so you can pick up extra ones as well as stand alone AC and USB modules that can use those extra batteries without being plugged into the main power station unit. Could be a game changer for trips where every member of the family is off in a different area draining some electronic device. I look forward to adding a "best modular power station" category soon.

Jackery Explorer 1500 Pro (1,512Wh): The latest in Jackery's flagship line of power stations. If you're already familiar with the Explorer Pro line, you won't find many surprises here. Some design improvements, but overall user experience remains unchanged. That is to say, this is a great robust power station that will deliver as promised. 

Portable power station FAQs

How many years do portable power stations last?

How many years a portable power station will last depends on three key factors -- how well the product is maintained, how often it's used and the battery type.

We have researched and spoken with several manufacturers and most units boast a 500-cycle lifespan. In some cases, such as the Anker 757, a unit may use LiFePO4 batteries compared to the more common li-ion battery and offer up to 3,000 cycles or beyond.

One cycle means using the product from fully charged to zero charge (or at least 80% in some cases). Therefore, if you use your portable power station several times a week, it might only last a year or two. But if you use it less frequently, it could last for much longer.

What can you run on a portable power station?

Portable power stations are generally designed to power smaller electronic devices and appliances, from phones and table fans to heavy-duty work lights and CPAP machines. Pay attention to the estimated watt-hours each brand provides in its specs to determine which model makes the most sense for what you'd like to power.

If a company says its portable power station has 200 watt-hours, it should be able power a device with a 1-watt output for about 200 hours. I go into more detail on this in the "How we test" section below, but consider the wattage of the device or devices you want to power and then the number of watt-hours your portable power station would need to have. 

Can a power station run a refrigerator?

Possibly, depending on the fridge and the portable power station. 

For example, this standard LG refrigerator has an estimated annual energy consumption of 608 kilowatt-hours. That works out to 1.67 kilowatt-hours per day, or 1,670 watt-hours per day. 

1,670 watt-hours per day works out to just under 70 watt-hours per hour. If you have a short-term power outage and only need to power your fridge, a 200-watt-hour power station could keep it running for nearly three hours. You'd need a power station with higher estimated watt-hours to run your fridge for longer. A mini fridge would last much longer than a larger model. 

Always confirm the electrical requirements for your specific fridge and portable power station before trying this, especially your refrigerator's peak and startup watts. 

How long can you run a portable power station?

You can get close to the answer with some basic math. If you have a power station that is rated at 1,000 watt-hours, and you plug in a device, let's say a TV, rated at 100 watts, then you can divide that 1,000 by 100 and say that it will run for 10 hours. 

However, this isn't usually the case. The industry "standard" is to say that you should take 85% of the total capacity for that math. In that case, 850 watt-hours divided by 100 watts for the TV would be 8.5 hours. 

The reality is that you should expect somewhere between 8.5 and 10 hours in this example.

How is a portable power station different from a generator?

A portable power station is essentially a big rechargeable battery that you carry around. Deplete it and it's useless until you can recharge. 

A generator, by definition is a device which actually will convert some type of energy to usable electricity in whatever circuitry you have it connected to. Examples of this would be gas generators -- commonly used as power sources for remote areas or as whole-home backups, electric generators -- not very common, but they convert some type of mechanical action to electricity and solar generators which can use solar panels to power devices or homes, often using a battery to temporarily store the electricity. These batteries are often portable power stations themselves. 

How we test

Every company that sells portable power stations provides the expected number of watt-hours its products are supposed to last. For the Jackery Explorer 240, that's 240 watt-hours; for the Ecoflow River Max, it's 576 watt-hours. Bluetti AC200P claims 2,000 watt-hours. 

That means if you run a device with a 1-watt output on the Jackery Explorer 240, it should last for about 240 hours. You'd get 576 hours from the Ecoflow model and a whopping 2,000 hours using the Bluetti generator. That would last you almost three months! For reference, a USB-C iPhone charger draws up to 18 watts, a 3-quart Instant Pot draws 700 watts and a standard microwave draws around 600 to 1,200 watts, depending on the model. 

Currently, we look at two main performance metrics for the portable power stations: charge time and discharge capacity. A power station's capacity should be a no-brainer. You should be able to look at a device's rated watt-hours and purchase accordingly based on your needs. And, generally, you can do that. I've found that you typically won't see the entire capacity rating as usable power, however. 

There are lots of factors that can affect this, and most of them center on how the manufacturer chooses to build their units' internals to manage their charged capacity. There is some (usually negligible) amount of power that goes to fuel the various indicator lights and readable led panels on the units. Some of the larger units even have their own operating systems, so it's almost like powering an additional mini-pc on the inside. Other units can have power-saving features where they reduce outgoing bulk power as they near depleting their charge.To run our capacity tests, we connect some number of 10,000 lumen LED work lights rated at 110 watts to each unit (the number of work lights is based on the overall watt-hour rating of the unit under test or UUT). We record the outgoing voltage and wattage using external measurement instruments or the UUT's own measurements if available. Once we have this data, we can math our way into a dizzying array of information about the UUT's performance. But the main piece of information we look at here is the observed capacity, based on our measurements, compared to the UUT's stated capacity.

Usable battery capacity comparisons for all tested portable power stations. 

Steve Conaway/CNET

In every case, that percentage ends up at less than 100%. (Most manufacturers say you should calculate expected usage at 85% of stated capacity.) Two of our smaller units both clocked 98% capacity -- the Jackery Explorer 240 and the Togo 350. Generally speaking, the midsize units didn't fare well. The largest units did better, with the Bluetti AC200P scoring highest at almost 96%. Now, if you blindly accept both a unit's stated capacity and our work light wattage rating of 110 watts, the numbers look very different. For example, we will take the GoSun PowerBank 1100 (to make the math easier) and attach four of the 110-watt lights. That load rating is now 440 watts and the GoSun's capacity of 1,100 divided by 440 is 2.5. We would expect to see 2.5 hours of usage. The actual run time for this unit was 2 hours, 50 minutes -- 113% capacity. Great! Right? Well, we're missing some key factors. Without going into a long(er) explanation of how to more accurately measure power, the fact that this unit has an output of 110 volts AC (compared to 120VAC) and the actual output wattage to the four lights is 352 watts, our real expected run time is 3 hours, 8 minutes, which drops the capacity rating to 90%.Here is the calculated capacity data for the tested units. One note for these numbers -- the Oupes data might be slightly off. The unit turned off the lights at 9%. It would allow me to start the lights again, but would turn them off again after some time. I repeated this process at least 20 times before the unit wouldn't power the lights for more than a couple of seconds at a time.

Charging performance can be nearly as important as knowing your actual capacity stats. It helps to know how long your device will take to charge, especially if you're crunched for time or need to be able to charge quickly for whatever reason. Will it take an hour? Two? Ten? Twelve (this is an actual number from our tests!)? We report three data points for charging performance. Each unit is plugged in for AC charging and we record how long it takes to reach 50%, 80% and 100% charge. Half-full is probably the least amount of power you're going to want, especially from the smaller units. 80% is the "magic number" for many rechargeable batteries. 

Keeping it simple-ish, imagine a swimming pool with room for 100 people, each person representing 1% of the total space. When you first start charging, and that first person dives in, you don't really have much to worry about. You're not going to run into anyone else, so dive, splash around, whatever you want. Now, as we add people, it gets a bit more crowded, and complicated. You've got less room for people. Once you have 80 people in the pool, that next person is going to take a few extra seconds to more carefully choose their entry so as to not cause any issues by just jumping and hoping no one is in the way.

Each manufacturer deals with this purposeful slow-down in their own way, so you won't see the exact same performance changes from one manufacturer to the next. And often true to the analogy, person number 100 into the pool can sometimes be very slow, taking several times longer to get in than any of his predecessors.

Take a look at the charging data. Charge times in minutes are listed, with a bonus "watt-hours-per-minute" metric that no one asked for other than myself. In most cases, you'll see how the charge rate is fairly constant between 0 and 50% and from 50 to 80%, then slows from 80 to 100%.

Charge times for all tested portable power stations from zero to 50, 80 and 100%.

Steve Conaway/CNET Here Are 23 Ways to Save On Your Electric Bills Right Now See all photos More home recommendations 

---