Everything You Should Know About Power Banks. Tech charge power bank

0mAh to 120000mAh: What’s the Best Capacity for A Power Bank?

Yes, there are fixes to stop your phone, tablet, or laptop battery from draining fast. But not everyone wants to compromise. That’s why portable power banks or battery packs exist.

For those who are new to power banks or have difficulty deciding which kind to get, capacity is the first and foremost thing to consider because it determines how often you can charge your device.

Ever wondered what the best capacity for a power bank is?

What Do You Need to Know About Power Bank Capacity?

I once explained about the numbers printed on power banks. Capacity is one of those complicated technical terms. But the rule is simple: the actual capacity of a power bank is about 2/3 of the rated capacity. Part of the energy will be lost in the conversion and during charging.

Capacity typically measures in mAh (Milliamp Hours), like our smartphone batteries. The bigger the number is, the larger the capacity. A power bank with a 10000 mAh battery has a capacity of about 6000-7000 mAh. The iPhone 12 mini has a 2227 mAh battery. So one full charge of a 10000 mAh power bank can charge the iPhone 12 mini from 0 to 100% two or three times (7000 divided by 2227).

If a 10000 mAh power bank can barely charge your iPhone 12 mini twice, then probably it’s so poorly made that too much energy loss happens during charging, it has a low conversion efficiency or simply contains far less capacity than claimed.

1000 mAh Power Bank

Power banks with a capacity less than that of the regular smartphone are rarely seen nowadays. To many, they seem pointless, but those who are not addicted to handheld entertainment may love the idea of a backup battery pack that they can attach to their key chains or keep in their wallet.

4000~5000 mAh Power Bank

A power bank of about 4000 mAh should suffice in ensuring your phone lasts well over a day even if you’re a heavy phone user, given that most people don’t leave the house with a dead phone. Phone users welcome these kinds of power banks with good reason: sufficient capacity with portability. If you are looking for a portable power bank for your phone, you may want to look at those 4000-5000 mAh power banks that can fully, or almost fully, charge your device. They’re also very portable and convenient to carry.

7000 mAh Power Bank

If you’re going to places where you regularly rely on your phone, and it may be a while before you come across a wall charger, then a medium-capacity power bank is the best option. A power bank with a capacity of around 7,000 mAh can not only charge your phone once, but you can share it with other people or charge other small devices like earbuds.

10000 mAh Power Bank

The average battery capacity of a standard smartphone falls below 4,000 mAh. So, a power bank with a 10,000 mAh capacity (actual capacity 6,000-7,000 mAh) is enough to fully charge most handsets at least once and charge small phones like the iPhone 12 mini three times. The downside is that power banks of this size tend to be larger and heavier than your cell phone.

20000 mAh Power Bank

A power bank with a capacity of 12000 mAh is more than enough for a smartphone. You can even charge a tablet like the iPad mini (5124 mAh) or Samsung Galaxy Tab S7 (8000 mAh).

If you have the iPad Pro 2020 with a battery of nearly 10000 mAh, or a standard laptop, then a 20000 mAh power bank seems to be the best option. After charging your iPad Pro once, the power bank still has energy left for a smartphone.

20000 mAh Power Banks

Power banks with a capacity of over 20000 mAh are comparably expensive and sizeable. So, be careful if you see some power banks with an extremely high capacity and an unreasonable price tag. They can support all your portable devices for a day and tend to be used for camping or traveling.

120000 mAh Power Banks

These kinds of power banks are more like portable generators, capable of lasting for days. They are usually found in a car’s trunk and can charge appliances, such as a mini-fridge. They typically feature multiple charging ports to charge several devices simultaneously.

What is the Best Capacity for a Power Bank?

As you already know, the more capacity a power bank holds, the more it can provide. On the flip side, the more powerful a power bank is, the bulkier it is. They also require a longer charging time and may not be allowed on flights.

You can’t have it both ways.

So, the best capacity for a power bank depends on your needs.

For regular phone use or a daily commute, take a look at power banks between 4000-5000 mAh, which are portable and have adequate juice.

For phone users with unique needs or for particular scenarios, 7000-10000 mAh are good options. If you want a power bank mainly for your tablet or laptop, they’d better be above 10000 mAh.

You might be interested in:

Everything You Should Know About Power Banks

Is there anything worse than battery anxiety? We’re all becoming dependent on wonderful mobile technologies such as smartphones to make our lives easier and more pleasant. While these devices have become incredibly power-efficient, we’re still pretty far away from only having to recharge once every few days.

Modern smartphones barely manage 24 hours of charge with moderate use, so we’ve grown used to moving our devices from one charger to the next. We charge at home, in our cars and at work. Just to keep that dreaded “low battery” warning at bay.

Which is why the ubiquitous “power bank” has become so popular over the last few years. These compact bricks of various sizes can store enough juice to keep your phone topped up for days. Power banks have probably saved the day more than anyone knows, but most people use them without really knowing anything about them.

Sure, a power bank is literally a “plug-and-play” product, but there are some things every user of these popular devices should know. After all, they are much more sophisticated than most of us realize. To help you be a more informed user (and buyer) of power banks, here are some essential facts you should commit to memory before using one again.

Power Banks Use (Potentially Dangerous) Lithium Ion Batteries

Battery technology is way, way better today than ever before. That might seem like an obvious observation, but few people remember how older technologies like nickel-cadmium took forever to charge and held barely any power.

Unfortunately, these modern wonder batteries come with some caveats. With such high energy densities, there’s always the chance that the battery will release it all in one uncontrolled burst.

That translates to an explosion or fire, which is pretty serious! You may have heard horror stories about houses burning down from faulty hoverboards or phones exploding in people’s s. That’s what happens when lithium ion batteries go bad.

The only reason the actual accident rates are acceptable comes down to the host of safety standards and technologies built into lithium devices. However, your power bank’s lithium battery can turn into a dangerous object through misuse as well. Being pierced or crushed is one surefire way of causing an internal short and subsequent flameout.

The same goes for being exposed to heat from lying in a hot car window or being too close to a heat source. So be circumspect about how you handle your new power bank and treat it with the correct level of respect.

At the same time, you should only buy and use power banks that are branded and have certification from consumer safety organisations. UL certification is probably the most common standard in the USA, with other territories having their own equivalents.

Power banks needs to have several features such as overcharge, overvolt and overheating protection to be considered safe for use. Unbranded, uncertified products may have only some or none of these features. Which is a recipe for disaster!

Power Bank Capacity Isn’t Always What it Seems

Power banks are almost universally rated in milliampere hours, abbreviated as “mAh”. This is a measure of how much electrical charge the battery can hold.

The battery inside your smartphone or laptop also has a rating in the same unit. So if you buy a 10 000 mAh battery and your phone sports a 2500 mAh battery, you should get four full charges out of it, right?

It turns out that there’s some mild marketing dishonesty going on here, as well as a measure of overhead thanks to the laws of physics.

The marketing spin has to do with the voltage difference between the battery and the device’s charging input. Lithium cells have a “nominal” voltage of 3.7 volts. However, USB operates at a minimum of five volts and so the device will expect to be charged at least at that voltage.

To see how this makes a difference we need yet another unit, the watt hour (Wh). This is the unit your electric bill is measured in and indicates the actual energy used.

Using an mAh to Wh calculator, we see that at 3.7V our 10 000 mAh power bank has 37 Wh of energy. However, our 2500 mAh phone battery charged at 5V needs 12.5 Wh. That only give us about three full recharges rather than four at best!

On top of this you have to consider that there is no such thing as lossless energy conversion. Converting the chemical energy in your power bank to electricity and back to chemical storage will dump some of it as waste heat.

In the end, you can roughly estimated the “actual” battery capacity of a power bank for charging devices at about two thirds of the capacity stated at a 3.7V nominal voltage. Some battery banks actually state two capacities at both voltages, which makes your job easier. Just remember that it’s the 5V number that actually matters.

The Amps Matter Too

Standard USB charging happens at 5V and 0.5A. If you leave the voltage the same and increase the amperage, the rate at which electricity flows increases. That means the bank will discharge more quickly and the target device will charge more quickly in turn. That is, if it supports charging at higher amperages.

Almost all modern smartphones and tablets can charge at 2.1A. Consequently it’s pretty common for power banks to have at least one port rated at 2.1A or 2.4A. It’s perfectly safe to plug any USB-compliant device into the high-amperage port. It will only receive as much current as it requests. Plugging your phone into this port will charge it at a speed similar to using a wall-charger.

know, power, banks, tech

There is a downside to this though. Faster discharging causes increased heat in the battery. The hotter the battery gets, the less efficient it is. So using the faster port could have a noticeable impact on how much charge you get out at the end of the day.

If you are trying to get as much out of the bank as possible, don’t actively use the phone and leave it overnight on the 0.5A output. Switching it off while charging would be optimal. This is the sort of scenario you’d encounter while camping away from mains power. Where every watt counts.

If you’re going to get to a place where you can recharge your power bank before you’re out of options, then it’s generally better to always use the high-amperage port. Especially if you want to actively use the phone for power hungry applications such as GPS navigation.

Speaking of charging, what about charging the actual power bank?

Quick Charge Standards Make All the Difference

If you have a modern, mid-range or better smartphone, you’ll know that it can charge pretty quickly from the wall. So it may be surprising when many power banks can take a whole day to charge up. There are various reasons for this, but if you are going to use a power bank often and not simply keep one for emergencies, faster charging times are critical.

Modern phones and tablets usually support one or another form of “quick” charging. There are too many charging standards to discuss here, but luckily all you have to do is ensure that the power bank’s stated supported standards match at least one of the standards your charger provides. This will cut down significantly on the total time it takes to top up the cells.

Pass-Through Charging Is a Useful Feature

Which brings us to another issue. Assuming that you only have one charger, should you charge your power bank or device first? If you have a power bank with support for pass-through charging, then this is one dilemma you don’t have to face.

Such power banks can charge themselves from the wall while also passing charge on to another device. One charger, two happy devices. It’s a feature worth looking out for.

Some Laptops Can Be Charged By SOME Power Banks

Phones,tablets and other small electronics have more or less standardized on 5V USB power, but laptops are different. These larger devices accept 12V power from a supply that converts the high-voltage AC current coming from the wall into something palatable for the delicate electronics inside your beloved lap-warmer.

You need to use a true USB-C cable that has the oval USB-C connector on both ends. Your laptop charger might use a removable USB C cable, in which case you can simply move it over to the power bank when needed. USB-C PD cables are rated for 3A, but some are rated for 5A. If your charger and laptop both support charging at 5A then it is worth getting a compatible cable. In most cases however you’ll get 3A charging with a total power delivery of 30W from the typical power bank designed for laptop charging.

Now, what if you have a laptop that doesn’t support charging via USB-C? Then you’ll need a special power bank with a 12V laptop output. This is a non-USB port that works with a proprietary cable provided by the power bank maker.

You Can Jump Start a Car With Special Power Banks

It’s true! There are some specialized power banks out there that come with an attachment that allows you to jump-start your car. These are more expensive than your run-of-the-mill power banks and are best left in a safe spot in your car.

They can be a real lifesaver, since not only can you get your car started with them, you can also juice up your phone to call for help if that doesn’t work. Now, to be clear, you can’t use any power bank for this purpose, but the basic power bank technology is the same.

Limited Lifespans Are The Order of the Day

One of the reasons that some people are none too happy that modern devices don’t have removable batteries is that a lithium battery is the one component that has the shortest lifespan. While the rest of your phone might work for decades unless you physically damage it, the battery will almost certainly be out of puff within a few years.

Lithium batteries gradually lose their charge capacity with every recharge. It’s not like an on-off switch where the battery will work one minute and then stop the next. The total amount of power that the battery can store just gradually becomes less until it really starts to drop off.

These days you can expect most lithium batteries to go through around 500 full charge cycles before starting to lose a noticeable amount of power. That’s a full recharge cycle. If you, for example, charge your power bank from 50% to 100% twice, that only counts as one full recharge.

You also can’t expect power banks to hold their charge indefinitely. So make a point of topping them up every few months if you haven’t used them.

Never Worry About Running Out of Power Again

Perhaps one day we’ll finally get that super-battery breakthrough that science journals are always promising. Some type of super-capacitor or room-temperature superconductor technology that will run a smartphone for 100 years.

For now, we’ll have to make do with battery technology that’s not quite magic, but definitely usable. Thanks to power banks, we can enjoy slim, attractive devices while also having some way to top them up when away from mains power or a car’s charging socket. No more FOMO or battery anxiety. As an informed power bank user, you can enjoy the benefits of having as much power as you need on tap. Wherever you are!

Review: EC Technology 22,400mAh Power Bank

High capacity power banks are not only able to provide a high capacity but they’re also able to provide more traits that make a charging experience better.

Having a high capacity can only be as good as what the charger has to offer. In this case, this EC power bank has some things to offer but are they things that make the charger better? Well not exactly.

This EC portable charger is able to talk the talk but its got some kinks that it still needs to work out a little bit. Now let’s take a look if high capacity is all a power bank charger needs to be awesome.

Similar 20,000mAh Power Banks:

Power Capacity

The first thing that you’re going to need to know about this EC power bank is that its got a power capacity of 22,400mAh.

With that said, quite a big chunk of the power is gone during charging and as a result, you end up with an 18,000mAh power capacity.

Just remember, this isn’t to say that the company lied about the power capacity, it’s just that the power capacity that you’re really going to receive after heat during charging, takes some power away and you end up with 18,000mAh.

However, this is still a big problem because in some cases this depletion in power can be avoided and be closer to the initial power capacity that a charger is supposed to hold.

With all that said, the 18,000mAh power capacity still places this power bank charger to still hold plenty of charges within it.

You can expect to charge many smartphones over 4 times. A tablet like an iPad can charge about 2 times or other tablets with smaller battery capacities can charge even more times.

Overall the power can last for days and probably even weeks depending on your usage with this charger.

EC Tech 22,400mAh Power Bank (Output Capacity = 18,000mAh)Phone CapacityEC Tech 22,400mAh Power Bank Left Over Capacity after One Charge

Now onto charging capabilities of the charger. The power bank has 3 charging outputs and each of them is able to charge at different charging speeds.

The most notable thing about the charging Output ports is that they have labels. The charging ports are labeled as iPhone, Samsung, and iPad. The logic here is that you’d plug in the device you need to charge that corresponds to the charging port. Here are the charging speeds each of the ports.

Powerful Charging

These charging speeds are actually pretty good considering that one is at the max standard charging speed (The iPad charging port) and another one is at 2 Amps.

The ports are somewhat labeled correctly as well because it makes sense to connect an iPad to the iPad port because that’s the max speed that it will charge at.

However, it makes sense to plug a smartphone into either the Samsung or iPad port if you’re not charging any tablets at all; because many smartphones can actually charge beyond just a single Amp, so the iPhone port is really only useful if you’re charging a tablet on one of the charging ports.

Then there’s the bad news to go with this power bank’s charging capabilities.

But has a Limit

Even though each of the ports is able to deliver some fast charging, they’re not able to deliver it all together. This is because the max output for the power bank is only 3.1A.

So if you plug an iPad into the iPad port the Output will be 2.4A and then if you plug a smartphone into the iPhone port, then the Output will be 3.4A; but that’s impossible since the max output can only be 3.1A.

So the iPad charging speed will be cut down to 2.1A so the total Output can be 3.1A.

This is where the power bank’s powering comes to a rather minimal disappointment because if you want to charge 3 devices at the same time, then this power bank will charge each of the devices at 5V/1.0A, which is some really slow charging.

However, this doesn’t mean that is power bank charges slow. It just means that you have to strategize on what you want to charge with what. Charging 2 smartphones is good. Charging 1 smartphone and tablet is good. But charging 3 tablets at the same time or 3 smartphones at the same time will not provide an ideal charging experience.

Input (Recharge Speed)

The recharging speed of this power bank is to be expected at 5V/2.0A via a Micro-USB Input port, and you can expect it to be fully recharged in about 8-9 hours.

For it to charge in the time that I mentioned, I highly recommend using the wall charger that is capable of charging at 5V/2.0A or higher, otherwise, anything lower will result in the power bank being recharged at a much slower rate.

Size and Weight

Like many other high capacity power banks, this one is quite big and heavy. It comes with the abilities of the power bank and it’s not something to be surprised about because of the bigger the capacity of a power bank, the more charging tech it has; means the bigger it will most likely be.

The portable charger’s length is 6.3 inches, 2.9 inches in width and it 0.8 inches in thickness. The weight of the charger is 1.4 pounds.

So ultimately, the “Portable” aspect of this charger is somewhat not present. Sure the power bank can be held in a single hand but are you really going to hold it in your hand, charge your phone and still use your phone? It’s half a foot long and it’s heavy.

With that said, it’s best to opt for the setting the charge down and using it. You can put it in a bag and use it at a location that you plan on staying.

Functional Components

The functional parts of the wall charger are in a few different places. The 3 charging ports are lined up one after another, with their labels under each of them but not the charging speed.

There’s a LED light that’s above the middle port. The LED light has 3 settings that can be changed via the power button, and the 3 setting of the light is Soft Light, Hard Light, and an SOS light.

Speaking of the power button, you can find it on the left side of the power bank, near the charging ports. Its functions are very limited because it’s only used to check the capacity of the power bank, turning off the power bank. If you hold it down for about 5 seconds.

Speaking of the power button, you can find it on the left side of the power bank, near the charging ports. Its functions are very limited because it’s only used to check the capacity of the power bank, turning off the power bank.

If you hold it down for about 5 seconds, it changes the LED flashlight settings. There are 4 LED power capacity indicators on top of the charger. You can find the Micro-USB port to the right side of the power bank.

The power bank has the ability to begin charging automatically and it turns itself off once the device it’s charging is fully charged.

When you recharge the power bank, the LED power light blinking according to what capacity the charger is at. So if it’s nearly full, the power bank will have only a single LED light blinking while all the other lights are just constantly on. Once the power bank is at full charge, all the LED lights are on.

The design of the charger is really straightforward and highly resembles the design of the KMASHI power bank. with a smooth and straightforward design.

Structure and Material

The entirety of the power bank is made of plastic and the structure has 3 main pieces that are connected to make the charger whole.

know, power, banks, tech

The top and bottom piece and a centerpiece of where all the functional parts are held are what make the power bank whole. Overall the charger does a great job at being structurally strong.


The charger has support for plenty of safety tech that includes Over-Voltage Protection, Over-Current Protection, and Short-Circuit Protection.

So even with its large capacity and ability charge 3 devices at the same time, you expect your devices to be very safe.

With that said, though, the charger can heat up and the result is the lessened power capacity. Even with its limited charging speed, the power bank is still able to heat up and I think this it’s bad quality on part of the batteries.

EC should consider the way they handle their temperature control during charging because this way the power capacity could be closer to the initial capacity.

The heat will only lessen the Amp current being sent out is lessened. Long-term heat will be able to damage the batteries.


This power bank poses itself to be reliable and it tries hard to deliver but I really don’t understand how it’s reliable when you’re going to be receiving a very mediocre charging speed.

The max output of this power bank is 3.1A. It would actually make more sense to get a 2 port power bank that has a similar power capacity like the PowerCore 20100 ; because it has nearly the same capacity but the max output of the PowerCore 20100 is 4.8A.

So this leaves most of the reliability to the capacity and it definitely delivers because of the power capacity, even with its missing chunk after some is lost during charging, is still able to deliver plenty of charges to smartphones and tablets.

The power capacity can very well last for days depending on the way you use it. And that’s really where most of the reliability end.

Sure, you can charge 3 devices at the same time, but you have to prioritize what devices you want to charge with what. You can’t charge 3 devices all at once and expect them all to charge at their max speeds because the max output is only 3.1A. So for fast charging, you have to be selective.

The portable charger isn’t very portable so you’re going to have to set it down and use it. Although this goes nearly all high capacity power banks since they’re heavy and large; and this charger is not an exception.


It’s got a real power capacity of 18,000mAh and can last for a few days with constant use.

The charging power of the power bank is on the weak side with 3 ports but the max output of the charger is only 3.1A. As a result you have to prioritize what devices you want to charge; otherwise, you’ll be stuck with slow charging.

Like many high capacity portable chargers, this power bank is big and heavy.

It’s not the best power bank to hold and use, but it will do very well if you set it down and use it.

All the functional parts are easy to find and use. Its design features are quite welcome with the charger being able to start charging automatically, and the power button being able to control the LED light, checking the power bank’s capacity and turning off the charger.

Made entirely of plastic throughout all of its pieces, the charger’s structure holds strong. On the inside is an array of safety tech that keeps your devices safe.

The charger can heat up quite a lot, which is the reason for such a loss of power capacity and the heat can damage the battery in the long-term.

It’s nearly a perfectly reliable charger when it comes to its capacity because it’s so big.

However, the reliability logic goes downhill after you consider the charging power. The charger only has a max output of 3.1A, so if you’re charging 3 devices at once, then they will charge slowly.

It’s a big charger, which is to be expected, so it’s best to use it in one place. But even with that logic, for what you’re getting, the charging experience will be mostly mediocre.


The EC high capacity portable charger tries to be better than it is, but it ultimately falls short.

The power capacity is still large, even with a good chunk of it missing. Although that missing power can be corrected if the tech was better at handling high temperatures.

The main thing to watch out for other than the large size and heavy weight of this power bank; is the charging speed and the charging ports. There are 3 ports but the overall max charge rate is 3.1A, which is very limiting if you plan to charge 2 devices or more.

The Best Portable Chargers and Power Banks for 2023

Is your phone, tablet, or laptop typically in the battery red zone before the day’s end? These portable chargers and power banks give you the most boost when you’re out of juice.

I love portable technology—if you can put it in a or a bag, I’m probably into it. I’ve covered phones and tablets of all shapes and sizes, and reviewed everything from game consoles to laptops in my decade-plus career. Prior to joining PCMag, I wrote articles for Android Authority, How-To Geek, MUO, New Atlas, Tom’s Hardware, and plenty of other tech publications.

Apple MagSafe Battery Pack (Credit: Steven Winkelman)

Watching your phone or tablet steadily run out of power when you’re nowhere near an outlet is stressful. Fortunately, third-party portable batteries are available in many sizes and capacities. Some power banks offer fast charging, wireless charging, built-in cables, AC adapters, and LED flashlights—and even the ability to jump-start your car. Regardless of your budget, you can find a portable charger that keeps your device going when your battery icon starts to dip into the red.

But with so many options to choose from, how do you know which one is right for you? Read on for our tips, followed by the most important points to consider as you shop.

Recommended by Our Editors

Best Affordable PD Power Bank

Anker PowerCore Slim 10000 PD

Why We Picked It

Despite its reasonable price, the Anker PowerCore Slim PD 10000 offers high-end features like USB Power Delivery for fast charging, as well as both types of USB ports.

Who It’s For

This 10,000mAh charger doesn’t have the highest capacity, but it’s more than enough for people who need just a little extra power throughout the day and don’t have the patience for slow charging speeds.

Best Ultra-Portable Power Bank

Anker 321 Power Bank (PowerCore 5K)

Why We Picked It

A huge battery capacity is convenient, but sometimes you need a small device that you can carry around without a backpack. The 5,200mAh Anker 321 Power Bank fits that need perfectly, especially because it offers both a USB-A and USB-C port.

Who It’s For

This is ideal for people who care more about portability than capacity. It won’t charge your phone multiple times, but it can still get you through a long day.

Best for Charging Laptops

Anker 737 Power Bank

Why We Picked It

The Anker 737 features 140W output, which means it can charge bigger, more power-hungry devices like a laptop just as effortlessly as it can juice up a phone or tablet.

Who It’s For

If you often need to charge a laptop when you’re nowhere near an outlet, this 24,000mAh backup battery can lower your stress levels. It’s more expensive than other options on this list, so people who tend to charge smaller devices like phones or tablets are better off with the more affordable choices.

Apple MagSafe Battery Pack

Why We Picked It

True to its name, Apple’s MagSafe Battery Pack is notable for its MagSafe support. You can simply stick it to the back of your phone to charge it wirelessly.

Who It’s For

If you need to keep your iPhone running while away from home, you won’t find a more convenient solution. People with older iPhones (before the iPhone 12) need to look at other options, though, as MagSafe isn’t supported.

Best High-Capacity Power Bank

Mophie Powerstation XXL

Why We Picked It

The Mophie Powerstation XXL does it all—it has a considerable 20,000mAh capacity, 18W PD charging, and both USB-A and USB-C ports.

Who It’s For

If you’re looking to recharge a phone or tablet several times on the go (and quickly), this is a top choice. The only drawback is that it doesn’t support larger devices like laptops.

Most Durable PD Power Bank

Otterbox Fast Charger Power Bank

Why We Picked It

Many people know Otterbox for its durable phone cases, but the company is now bringing that expertise to the world of power banks. In addition to its strong build quality, the Otterbox Fast Charger Power Bank has all the key features you need, such as fast charging with PD, both types of USB ports, and several options for battery capacity.

Who It’s For

If you are worried about damaging your backup battery when you travel or commute, this is one of the safest bets. It also comes with a limited lifetime warranty.

Best Solar-Powered Portable Charger

QiSa Solar Charger

Why We Picked It

The QiSa Solar Charger can use the sun to recharge itself, supports both wired and wireless charging, and even has a built-in flashlight. Best of all, it offers a massive 38,800mAh capacity.

Who It’s For

If you spend a lot of time outdoors, this is among your best choices for keeping your devices running while off of the grid. In other words, it’s camping approved.

What Size Battery Do You Need?

On the.friendly front, most smaller batteries have a capacity of around 5,000mAh, which is typically enough to top up most phones once.

Meanwhile, a 10,000mAh battery can give today’s flagships two full charges. A 20,000mAh battery can charge a flagship four times, or two phones two times. Some power banks have enough juice to power laptops. Of course, a higher capacity often translates to a heavier, larger, and more expensive battery.

Most companies advertise how many times their products can recharge popular phones, but if you want to calculate that number for yourself, RAVPower has a useful guide (Opens in a new window) that can give you an estimate.

In the end, it’s best to assess your typical needs before buying. If your phone hits the red zone by mid-afternoon and you only need enough juice to get you to the end of the workday, a 5,000mAh battery should be plenty.

What’s the Difference Between Power Input and Output?

You’ll find three types of ports on today’s portable batteries:

Generally speaking, you charge the battery itself via micro USB or USB-C (input). Some batteries charge faster than others and USB-C charges much faster than micro USB.

Nearly all batteries include a standard USB-A port (output). This is for plugging in USB-A-to-micro-USB, USB-A-to-Lightning, or USB-A-to-USB-C cables for charging your iPhone or Android device.

Some batteries include built-in output cables and these generally have micro USB, USB-C, or Lightning connectors.

The most important thing to do is to match the battery’s output to your phone’s input. For example, if you have an iPhone, be sure the battery has its own Lightning connector or supports USB-A-to-Lightning or USB-C-to-Lightning cables.

Larger batteries with higher capacities might include a multitude of ports to support input and multiple outputs at the same time. You may see two USB-A and two USB-C ports, for example, though micro USB ports are becoming less common.

If you picked up an iPhone 13 or iPhone 14 and were surprised by the lack of an included wall charger, see our article on charging your iPhone.

What Is Fast Charging?

Another factor to consider is how quickly a power bank can charge your device. Battery output is measured in voltage and amperage. Amperage (or current) is the amount of electricity that flows from the battery to the connected device, while voltage is the amount of potential energy. Multiplying volts by amps gives you wattage, the measure of total power. To make devices charge faster, most manufacturers either vary the voltage or boost the amperage.

Today’s devices support a wide range of Rapid-charging technology, such as Qualcomm QuickCharge, USB Power Delivery, or proprietary fast-charge systems.

Quick Charge works by increasing voltage rather than amperage. This standard typically allows you to charge supported phones to 50 percent capacity in 30 minutes, which is especially helpful when you need power in a pinch.

Power Delivery is a newer protocol in which two compatible devices negotiate on the fastest charging option available based on the charger, cable, and circuitry. It also allows for power to flow both ways.

The most common devices (Apple iPhones and Samsung Galaxies) support charging rates of 27W and 45W, respectively. It’s best to look for batteries that can support charging in that range.

Is Pass-Through Charging Safe and Useful?

Pass-through charging is another feature to consider; with it, you can charge devices and the portable power bank simultaneously. That’s convenient if both your phone and backup battery are running on empty. You shouldn’t encounter any safety issues if the manufacturer of the portable battery you buy advertises pass-through charging as a feature, but the power output might change in this mode.

How Does Wireless Charging Work?

Wireless charging has become popular because it allows you to power up compatible devices without a cable. Qi is the dominant standard for compatible Android phones (up to 18W) while Apple iPhones rely on MagSafe charging (up to 15W). iPhones will charge wirelessly on Qi chargers, but only at 7.5W.

Some battery makers have built Qi or MagSafe-compatible wireless charging into the surfaces of their portable batteries. Such batteries mean you can leave the cables at home.

Should You Buy a Battery Case Instead of a Power Bank?

If you find that you often forget to carry your backup battery when you need it most, you should consider a dedicated battery case instead. These combine the portability and protection of a case with additional battery capacity to keep your phone topped off at all times.

There are several drawbacks. First, they have limited additional capacity on board. Second, they are limited in terms of the number of phones they support (mostly just iPhones, Galaxies, and Pixels). Third, you can’t charge much else with them.

The Best Wireless Chargers

Why fumble around for a charging cable when you can rest your phone on a wireless charging pad? Whether you’re an Android user or an iPhone fan, check out our roundups of the best wireless chargers and the best MagSafe chargers to help you cut the cord.

Steven Winkelman contributed to this story.

Leave a Comment