Welcome to PowerBank20! An independent website where we test portable chargers – also known as Power bank – on Amazon in order to recommend the best 20 models.
We are aware of the difficulty of choosing a quality and good performance power bank to charge our devices due to the infinity of brands and models we can find on Amazon with different features and prices.
For this reason, we have 2 clear goals:
- Turn the Reader into a Power Bank Expert: By reading our Guide, you’ll learn everything you need to know to buy the model that best suits your needs.
- Test and choose the 20 Best Power banks on Amazon: we constantly test new portable chargers with the aim of recommending those that really surprise us and are worthwhile.
We encourage you to read our Guide and share it in your social networks and, of course, if we aren’t able to solve your doubts, you can leave us your question in the comments section below and we’ll answer gladly! 🙂
- 1 What is a Power bank?
- 2 How does a Power bank work? Features
- 3 How to recharge a Power bank?
- 4 How to charge your devices the right way?
- 5 Power bank actual output capacity, efficiency and performance
- 6 How many times can I charge my phone with a Power bank? 📱
- 7 How to buy the best Power bank according to your charging needs?
- 8 List of the 20 Best Portable Chargers on Amazon (July 2021) 🚩
- 9 How we tested a Power bank 📊
- 10 Can I bring a Power Bank on a plane? ✈
- 11 Pros and Cons of Having a Power Bank
- 12 Frequently Asked Questions (FAQs)
What is a Power bank?
A power bank is a portable charger that will allow you to recharge your smartphone at any time and anywhere you want. This accessory becomes a must for travelers who spend long hours on a means of transport without being able to recharge their phone.
With the security of a portable charger for your electronic devices, you will be able to enjoy your applications, social networks and games such as Fornite without worrying about battery life.
Here on our website, we will help you choose the best power bank for you that fits the needs you really need.
How does a Power bank work? Features
A power bank is basically a lithium battery with a printed circuit board (PCB) that controls its operation.
When we connect the smartphone to recharge through the USB port, the power bank identifies the connected device and supplies the necessary power that such device can receive.
The following picture shows the basic components of a power bank, as you can see its construction is simple:
- PCB: integrated circuit that regulates the voltage and protects the lithium battery from overloads. It includes a USB port and micro USB to charge devices of these kinds respectively and the lithium battery of the power bank itself.
- 18650 lithium-ion battery with a specific capacity (mAh) and voltage (~3.7V).
How to recharge a Power bank?
Just like a smartphone, a power bank is recharged through a charger, connecting it to its Micro USB or USB C input port.
In addition, most current power banks, especially high-capacity models, also incorporate the Quick Charge (QC) or Power Delivery (PD) fast charging technology at their input port.
For this reason, we must differentiate between the 2 types of recharge that a power bank has:
- Standard Charge: it is the conventional charge that is done with any charger at a voltage of 5V.
- Fast Charge: it is a new charging system that works with a higher voltage (9V or 12V). It requires the use of a charger compatible with this technology.
How to charge your devices the right way?
In this section, you will learn to identify the specifications in the USB output ports of your power bank, this in order for you to choose the model that satisfies best your device’s charging needs.
As you already know, a power bank is able to charge most electronic devices with a USB port: cellphone, tablet, iPad, bluetooth headset, ebook reader, fitness tracker, smartwatch… even an E-cigarette or a laptop.
In addition, for the new generation cellphones, the fast charging technologies (such as Quick Charge and/or Power Delivery) are also available in the output ports (either USB-A or USB-C) in many power bank models, therefor, we can distinguish 2 different ways to charge our devices:
- Standard Charge: the output voltage is always of 5V, this is the default charge offered by any power bank.
- Fast Charge: it works with a higher voltage superior to 5V (such as 9V or 12V) in order to supply more power to the device during the charging process.
Note: The power bank must be compatible with the fast charging protocol implemented on the connected device, otherwise, it will trigger the default charging mode at 5V.
The following image shows the technical specs of model PBD01 by Tronsmart:
It can be seen on the label the type of USB output ports: USB-A and USB-C, the range of charging tensions supported: 5V-12V and the maximum current values (A) and power (W) supplied by each port:
- USB-A Output: DC 5-6V/3A, 6-9V/2A, 9-12V/1.5A (18W)
- USB-C PD Output: DC 5V/3A, 9V/2A, 12V/1.5A (18W)
Note: although the type C port shows the Power Delivery protocol, we also verified that it supports Quick Charge 3.0.
That is, with this power bank we can charge devices in both Standard Charge (5V) and QC 3.0/PD Fast Charge through its 2 output ports: USB-A and USB-C.
Being that said, you may come up with the question:
What smartphones can we charge with this power bank?
Lets see some examples:
The Google Pixel 3 has type C port and fast charging via the Power Delivery (PD) protocol only.
If we connect Pixel 3 to port C of the Tronsmart Trim power bank, its Fast Charge system would be enabled (compatible with PD) and the Pixel 3 will charge in less time than Standard Charge mode.
Instead, if we connect it to the USB-A port of the Tronsmart Trim (by using a USB-A to a USB-C cable), the Google Pixel 3 would charge at 5V (Standard Charge) since this port is compatible with QC 3.0 and the Google Pixel 3 doesn’t support Qualcomm Quick Charge protocol.
The Xiaomi Mi 5 counts with a type C port and fast charging through the Qualcomm Quick Charge (QC 3.0) protocol.
In this case, the Xiaomi Mi 5 may be plugged to the USB-A or the USB-C provided by Tronsmart Trim to be charged via QC 3.0.
Logically, for the USB-C port we would need a cable with USB -C connection in both ends.
Power bank actual output capacity, efficiency and performance
The indicated capacity in a power bank is the nominal capacity of its internal battery at a determined voltage, generally it is in the range of: 3.6V, 3.7V, 3.8V or 3.85V.
But the above mentioned capacity is not the actual output capacity that we have available in a power bank output to charge a device, that is:
We have already seen in the Power Bank’s specs, the range of possible voltages you may have in its USB output port: 5V, 9V or 12V.
That said, during the charging process of a device (or discharging the power bank), the internal circuit of the power bank increases the battery voltage (e.g. 3.7V) to the charging voltage of the device (e.g. 5V).
This process of conversion of voltage has an energy cost in which some energy is wasted in the form of dissipated heat.
Depending on the design and quality of the internal circuit components, the power bank will be more or less efficient to transfer its stored energy to the devices to be charged.
Therefore, we can define the discharge energy efficiency of a power bank as the energy it is able to supply based on its stored energy:
Power Bank discharge efficiency = output energy / input energy
In order to have a better understanding of this formula, let’s see an example:
On the Model PB108 specifications of the Ugreen brand, it shows that it has a battery with a nominal capacity of 10000mAh (milliamps per hour) at a voltage of 3.8V (volts) being the stored energy of 38Wh (watts per hour), this results of multiplying capacity (Ah) by voltage (V): 10Ah x 3.8V.
If we completely discharge the Ugreen power bank, we will get the actual capacity and energy available to supply our devices:
|Type of charge||Actual output capacity||Output energy||Conversion Rate|
|Standard (5.1V/2A)||6864mAh||34.89Wh||34.89/38 = 91.82%|
|QC 3.0 (7.3V/1,9A)||4701mAh||34.34Wh||34.34/38 = 90.37%|
As you can see in the table above, the actual capacity obtained would be different depending on the tension we charge our devices: 5.1V or 7.3V.
Although it’s not a very common practice in power bank manufacturers, in this case, Ugreen already indicates us that the minimum output capacity is 6500mAh (or 33.15Wh) for Standard Charge (5.1V/1A).
Efficiency vs Performance
No matter how efficient a power bank may be, what is its purpose? really, do you know what its main purpose is?
The purpose of a power bank is to charge one or more devices as many times as possible.
Put in different words:
The more power a power bank can supply, the more devices can be charged.
Obviously, the larger capacity (mAh) a power bank has, the most energy it stores (Wh) and, thus, the greater number of devices it will charge (unless it had a poor energy efficiency).
That is to say that with a 20000mAh power bank, you will be able to charge more devices than with a 10000mAh since the stored energy is larger: 74Wh vs 37Wh.
However, when comparing models with the same capacity, we should not focus only in knowing which one is more efficient, but also, which one can supply more energy, because the nominal voltage of the battery that incorporates the power bank plays an important role.
For this reason, when we talk about the performance of a power bank, we are referring to the number of possible charges the user will be able to get in one or more devices.
Commonly, the more efficient a power bank is, the more stored energy it can supply, although we may also find other less efficient models but that provide more energy, i.e. they have a better performance.
The following table shows the energy and efficiency results obtained in the Standard Discharge (5V) of several power banks with the same capacity:
|Power bank||Rated capacity||Battery voltage||Stored energy||Output energy||Conversion rate|
Both models have a battery with the same rated capacity and voltage, so, they accumulate the same energy (37Wh).
In this case, the most efficient power bank will be the one with the best performance: Omars.
These models have a battery with the same rated capacity but different tension, being the stored energy larger in the Ugreen power bank (38Wh).
Although Omars is more efficient than Ugreen (93.73% vs 91.82%), it supplies less energy (34.68Wh vs 34.89Wh), so, before the user, Ugreen has a better performance than Omars.
Finally, we see that Aideaz is the power bank that supplies more energy (35.83Wh) with less stored energy (36Wh) being also the most efficient model (99.53%).
In terms of energy, Aideaz could be considered an ideal power bank:
It is capable of transferring its stored energy to the connected devices with the lowest energy waste (most efficient) and the highest possible number of charges (most performance).
How many times can I charge my phone with a Power bank? 📱
With the following tool you can find out the number of charges that you will have in your smartphone through the Standard Charge of a power bank:
Did you expect more charges on your smartphone?
As we explained in the previous section, the real capacity of a power bank is always lower than the one adversited, that is:
You can’t just divide the Power bank’s capacity into the phone’s batery capacity in order to calculate the number of charges you will have on your smartphone.
If you want to learn more, you can read this article about the power bank real capacity.
How to buy the best Power bank according to your charging needs?
In this section, we will highlight the most important features you need to take into account when buying a power bank, according to your charging needs.
Before starting, we would like you to answer the following questions that will help you to have a clearer idea of which type of power bank you are really looking for.
- What kind of device you need to charge with a power bank: smartphone, tablet, iPad, laptop, bluetooth earphones, smartband, camera…?
- How often will you use it? Only on trips, on a daily basis…?
- How many times do you want to charge your phone with a power bank?
- Do you need your power bank to have a fast charging system?
The more capacity (mAh) a power bank has, the more times you can charge your devices but it also affects their size, weight and price.
For this reason, we say that it is important to be clear about which devices you are going to charge and how often:
For example, during trips or travels, it is recommended to use a 20000 mAh power bank to charge your smartphone and other devices without having a power plug for several days.
Tip: If you need more capacity but you are going to take a flight, please check that the power bank may be carry-on luggage.
Now, if your idea is to use a power bank daily to charge your smartphone at work, college, school… with a 5000 mAh power bank or a 10000 mAh one it will be more than enough for a full charge, besides the practicality to carry it with you.
Are you looking for a power bank which allows you to have N number of charges on your smartphone? If so, then you can check in the previous section what power bank capacity you will need.
Generally, the amount of USB output ports of a power bank will depend on its capacity, that is to say:
High capacity power banks (10000 mAh or more) usually include at leat 2 output ports to allow multiples devices to be charged at the same time, whereas other models with smaller capacity (5000-6000 mAh) have a single USB port because they are designed to charge phones only.
Obviously, there are exceptions to this, as in the case of some models of 10000 mAh of the Anker and RAVPower brands which include only one USB port.
Choosing the number of ports of the power bank will depend on the individual needs of each user. Prior to selecting a particular model, remember to ask the following question:
How many devices are you planning to charge? Are you going to share your power bank with your relatives or friends?
It is important that the power bank be light and easy to carry so it may not become an unnecessary and useless gadget.
After all, the user is interested in carrying portable power in a device that takes up as little space as possible.
Normally, the more capacity the power bank has, the larger its size, thickness and weight.
However, the use of lithium polymer batteries (LiPo) which substitute the classic 18650 ion lithium (Li-Ion) ones, have achieved to reduce the thickness of the power banks and thus offer more compact models, with dimensions and/or thickness similar to that of a smartphone, an example of this would be the Ultra Slim models.
Currently, a power bank with fast charging technology generally has a higher tag price than a power bank that only offers the standard charging. However, this has its advantages:
- 2×1: This offers both Fast Charge as well as Standard Charge for each of your devices.
- High capacity power banks can recharge in less time.
- Current and future smartphones use the fast charging technology.
Deciding on whether or not to choose a fast charge power bank will only depend on what devices you will need to charge and on your budget. Besides, many brands offer the same power bank model without fast charge.
To sum up:
If your smartphone doesn’t have this technology and you are not thinking to change it in the near future then you may buy a simpler and more affordable power bank.
On the other hand, if you want to enjoy the fast charge in your smartphone, the power bank must be compatible with the fast charging protocol of your smartphone: Quick Charge, Power Delivery, Huawei FCP, Dash Charge…
Do you have a phone with a USB-C charging port?
The new reversible USB type C port is present in the new mobile generation and the trend is that it will keep on growing in the future as the substitute of the classic micro USB port.
Similarly, the new power banks come with the USB-C port as an additional port or as substitute of the micro USB input port, since it may work as input-output port.
In addition, the fast charging protocol or Power Delivery is designed to only work with this port.
This is why, if you have a smartphone with a USB C port or you are thinking to purchase a new device in the future, it is advisable to use a power bank with a USB C port.
It is always important to check the technical features of the power bank you are going to buy and compare them with similar models of other brands. For this, ask yourself the following questions:
- What type and how many USB input ports does the power bank have to recharge?
- Does it come with a micro USB, Lighting port, or does it include the new USB type C port?
- Does the micro USB port support Qualcomm Quick Charge (QC) technology or it only has the Standard Recharge (5V)?
- Similarly, does the USB-C port support Qualcomm Quick Charge (QC) and/or Power Delivery (PD) or it only has the Standard Recharge?
- In the case of Standard Recharge, what’s the maximum power admitted in this port? 5W (5V/1A), 10W (5V/2A), 12W (5V/2A), 15W (5V/3A…)?
Tip: the more power (W) the power bank admits, the less time to it takes recharge it.
- What types and how many USB output ports does the power bank have for charging devices?
- Does it have a USB-C port or only the classic USB-A?
- Do USB-A ports support Quick Charge or only work with the Standard Charge?
- Likewise, does the USB-C port support Quick Charge and/or Power Delivery or only Standard Charge?
- In the case of Standard Charge, what’s the maximum power that each port can supply? 5W, 10W, 12W, 15W…?
Tip: The more power (W) the portable charger can supply, the faster your devices will charge.
Finally, you may also find power banks with accessories and additional features that adapt to a particular need, for instance : It
- comes with an integrated cable
- has an LCD screen to visualize the charge level
- has a LED flashlight
- is water resistant or anti-shock power banks
- works as a jump starter.
List of the 20 Best Portable Chargers on Amazon (July 2021) 🚩
To save you this whole process of searching for a quality power bank and after having thoroughly studied the market of portable batteries, we have developed our list with the 20 top models you can find on Amazon in a wide range of prices, sizes and capabilities.
How we choose the best Power banks
We find difficult to establish a single criterion to choose the 20 Best Power Banks, since many factors must be taken into account depending on each user’s charging needs and, of course, on their available budget.
However, after having compiled a large amount of information on the features and operation of many power banks in the market, we think we can establish a reliable criterion to recommend the best models.
Before starting, we would like to clarify 2 concepts that might confuse the user:
- The user should not confuse the official ranking of Amazon’s best-selling power banks with Amazon’s best power banks.
- A power bank with more ratings does not always mean that it is better than another model with lower rating.
Here are the main factors we have taken into account to choose the best portable chargers on Amazon:
Although product appearance is not the most relevant factor, we attach some importance to packaging, i.e. how the seller presents and protects the power bank and what information it displays in the box itself, as well as the contents of the box:
If the power bank has a USB-C port, we will value that a cable with USB-C connector or an adapter for it is included.
In addition, if the power bank supports fast recharge through Power Delivery, we will value that the same cable is compatible with this technology so that the user does not have to buy an additional cable..
Also, we appreciate small details that the brand has with its customers, such as including a little carry pouch or a Lightning adapter.
Containing flammable batteries inside, the power bank must be made of material resistant to knocks, falls and scratches and, obviously, include protection circuits against short circuits and overvoltages in order to protect your devices.
Some brands use aluminum housings while others opt for high quality plastic and even some models are covered with rubber to isolate them from blows or to improve their grip (anti-slip).
Although power banks with an aluminum housing have an aesthetically pleasing design, they are also more prone to scratches and dents. We prefer more robust models made of high quality plastic.
We value those power banks that offer the same benefits as other models but with a smaller size and lighter weight.
We are supporters of the power banks that meet the charging needs of the current smartphone market: the models with fast charging technologies, wireless charging and USB type C port have a greater presence in our ranking.
For example, we consider, almost essential, that the input port of a large capacity power bank (>= 10000 mAh) has a fast charging system (Quick Charge and/or Power Delivery) in order to avoid long waiting times.
However, we’ve also wanted to recommend some models without fast charging (only standard charging) for those users who are looking for a simpler and cheaper power bank.
What other features do we consider?
- Admitted power at the input port: a power bank that recharges to 5W (5V/1A) is not the same as another that recharges at 10W (5V/2A).
- USB output ports: it should have at least 2 ports (USB-A and/or USB-C).
- Power supplied to a device: Which power bank supplies more power per port? What is the total power it can deliver among all its output ports?
We also like to rate who is behind the product and what guarantee it offers to the customer:
- Is it a company specialized in smartphone charging devices? Or is it a seller who only imports products of questionable quality from China?
- What guarantee does it offer if the power bank fails a year after purchase?
Until now, all the factors analyzed can be checked by the readers themselves with the product information available on Amazon.
Also, if you also read the previous sections of this guide and our buying tips, you must already be a power bank expert!
However, there are other important parameters to analyze in order to distinguish between a good and an average model.
But, to do this, it is necessary to have the power bank in your hands and test it thoroughly. That is our job!
For that reason, in our valuation criterion, we take into account the different tests performed on a power bank:
- Efficiency in recharging
- Efficiency in discharging
- Maximum power/port
- Total power reached
- Standard and fast simultaneous charging
- Fast charging protocols supported
- Low Power Mode
- Charge devices and power bank at the same time (Pass Through Charging)
Our goal is to recommend quality power banks (previously supervised by our technicians) that offer the best performance at the lowest price.
How we tested a Power bank 📊
At Powerbank20, we aim to recommend our readers the best Amazon power banks in a critical and neutral way, that is:
Without being influenced by the customer reviews of Amazon and the “advertising” recommendations of influencers and webs from the tech sector.
In order to accomplish this difficult task, we must buy, test and compare a large number of power banks of different brands, features and prices.
Below, we will describe the technical tests performed on each power bank that will help us decide, along with other factors, which are the best ones:
Charging and discharging test
A full charge and discharge of the power bank is made by measuring each stage with this USB multimeter:
Thanks to these measurements, we can know, among other data, a power bank’s charging time, its real capacity or how efficient it’s to recharge and discharge it.
In addition, we’ve created a basic report in real time that answers the following questions of general interest for our readers.
Simply select the type of discharge: Standard (by default), Quick Charge or Power Delivery and the capacity to compare among several power banks correctly :
A device will charge faster with a power bank that can supply the power required by said device, that is:
If the device can be charged at 10W of power, the power bank should be able to supply those 10W (5V/2A) without problems.
Also, if the power bank has 2 or more USB output ports and we want to charge several devices at the same time, it is important to know the total power the power bank can supply.
In our tests, we checked the maximum power that each USB output port of the power bank can provide and the total power that all the USB output ports can supply at the same time.
Finally, we performed other checks that can make the difference between one model and another:
- Pass Through Charging: if you can charge a device at the same time as the power bank is recharged.
- Low Power Mode: if you can charge low power devices such as smartbands, Bluetooth headsets…
- Simultaneous Standard and Fast Charge: when we charge several devices at the same time, if the power bank is able to maintain the Fast Charge function or, conversely, disables it by working all its ports in Standard Charge.
Can I bring a Power Bank on a plane? ✈
Many users wonder if it is possible to bring a portable charger on a plane and the answer is YES, IT IS POSSIBLE AS HAND LUGGAGE.
According to the International Air Transport Association (IATA) in its Dangerous Goods Regulations, the power bank is considered as a spare battery and can not be checked-in, it can only be carried as hand luggage, as long as it does not exceed the nominal capacity of 100 Wh(Watt-hour):
Although the airlines are governed by these regulations, you can check their documentation on dangerous goods if they include other restrictions for portable chargers:
How to check if your Power Bank is allowed on a flight?
Typically, the power bank specification sheet usually indicates its rated capacity in Ah y Wh but if you can not find it you can always calculate it for yourself:
As you will already know, a power bank consists of a set of lithium-ion batteries with a certain capacity and a common voltage of 3,7V.
To know the rated capacity in Watt-hour (Wh), you must multiply the power bank’s total capacity indicated in mAh by this voltage and divide it by 1000:
Rated Capacity (Wh) = (mAh x V) / 1000
If our portable charger has a capacity of 20000 mAh at a voltage of 3,7V, the rated capacity will be:
Rated Capacity = (20000 mAh x 3,7V) / 1000 = 74 Wh < 100 Wh ✅
In the event that you carried in your hand luggage 2 portable chargers, you would have to add the total capacity and verify that you do not exceed 100 Wh:
- Power bank 10000 mAh = 37W
- Power bank 20000 mAh = 74W
Total Capacity = 111 Wh > 100 Wh ❌
Pros and Cons of Having a Power Bank
Are power banks necessary?
Below, we list the advantages and disadvantages of the need to have a portable charger as an accessory for our mobile phones.
The mobile phone has become the center of our lives, we communicate through WhatsApp, we manage our trips (ticket purchases, reservations …), we send emails, we buy online, we have fun on YouTube, social networks… and we now even pay through it.
For this reason, we believe that our mobile phone always has to be available at any time of the day without worrying about the lack of battery.
A portable charger is our great ally, as it allows us to stay always connected and guarantees that we will have extra energy to reach the end of the day. These are some of the most important advantages:
And what about the disadvantages? Like any other product, portable charges also have their drawbacks:
Have you thought about whether you really need to buy a Power Bank?
If you spend all day away from home or you often travel frequently, it may be useful to carry a portable battery, but, if in your everyday life, you see that you have enough battery in your mobile phone until you get home, you can avoid buying an extra gadget…
On the other hand, a low quality power bank can be dangerous and even explode due to a factory defect or a user’s misuse.
It is advisable to always read the manufacturer’s instructions, look for specialized brands in those products and flee from super low-priced offers.
Frequently Asked Questions (FAQs)
If you have any other doubt that has not be answered, you can write it in the comments below.