Running out of battery while on the go is really troublesome, isn’t it?
However, when you actually try to buy one, there are so many types and technical terms that many people might wonder, “Which one should I choose?”
If you make the wrong choice, you might not be able to use it as expected, or in the worst case, there is even a risk of it leading to an accident.
Among all factors, safety is the most important part that can never be compromised.
In this article, to help you avoid making mistakes when choosing a power bank, I will explain five truly important points that I want you to keep in mind from my perspective in an easy-to-understand way.
Specifically, we will look in detail at product specifications such as capacity (mAh), output (W/A), fast charging standards, and input, types and number of ports, and size and weight, in addition to the particularly important aspect of safety.
What you will learn in this article!
5 Points to Avoid Failure with Power Banks
By understanding these points, you will surely be able to find the perfect power bank for yourself.
Capacity (mAh)
- Compare power bank capacity with device battery capacity: Confirm how many times you can charge your own device.
- Check size and weight: Consider the balance between portability and battery capacity.
- Assume usage scenarios: Choose the optimal capacity based on whether it’s for daily use, long trips, or outdoor activities.
Capacity refers to the amount of electricity that can be stored in a power bank, expressed in mAh (milliampere-hours).
The larger the mAh value, the more electricity can be stored, allowing for multiple charges of smartphones and other devices.
| Capacity (mAh) | Main Intended Use | Smartphone Charge Estimate (4000-5000mAh base) | Size/Weight Trend |
|---|---|---|---|
| Below 5000 | Emergencies, focus on lightweight/compact | Less than approx. 1 charge | Small/Lightweight |
| 5000-10000 | Daily use for 1–2 smartphone charges, focus on portability | Approx. 1–1.5 charges | Slightly small, relatively lightweight |
| 10000-20000 | Multiple smartphone charges, tablet charging | Approx. 2–3 charges | Standard size and weight |
| 20000 or more | Long trips, outdoors, laptop charging, disaster prevention | Approx. 3+ charges | Large/Heavy |
Ms.ガジェットHow specifically should I calculate how many times I can charge my smartphone?
Mr.ガジェットA realistic estimate is obtained by dividing about 70% of the labeled capacity by your device’s battery capacity.
While a larger capacity stores more power, it also affects size, weight, and price. It is important to choose based on the balance between capacity and portability according to your usage.
Output (W/A) and Fast Charging Standards (PD/QC, etc.)
Output refers to the amount of power supplied from the power bank to the device, expressed in W (Watts) or A (Amperes).
The higher the output, the faster the charging speed.
Also, PD (Power Delivery) and QC (Quick Charge) are fast charging standards that enable higher speed charging between compatible devices.
Mr.ガジェットPD is especially important!
For example, for fast charging a smartphone, it is convenient to have at least 18W of output.
Furthermore, if you want to charge a tablet or laptop, you need to choose one that supports higher outputs, such as 45W or 60W.
Mr.ガジェットEspecially high output is often required when charging a computer.
| Device Example | Estimated Required Output | Fast Charging Standard Examples |
|---|---|---|
| Smartphone | 18W–35W | PD, QC |
| Tablet | 30W–45W | PD, QC |
| Laptop | 30W–100W | PD |
Here is a table summarizing the features of PD and QC.
| PD Version | Release Date | Max Power | Max Voltage | Key Features |
|---|---|---|---|---|
| 1.0 | July 2012 | 100W | 20V | Communication with 5 fixed power profiles |
| 2.0 | August 2014 | 100W | 20V | Up to 100W supply and USB-C Alternate Mode for video/data via one cable; automatic optimal power negotiation with backward compatibility |
| 3.0 | 2015–2017 | 100W | 20V | PPS※1 for fine-grained voltage adjustment in 20mV increments and heat reduction |
| 3.1 | 2021 | 240W | 48V | Introduced EPR (Extended Power Range) mode for power supply exceeding 100W; bidirectional power, hub communication (optional) |
※1 PPS (Programmable Power Supply) = A mechanism that efficiently charges by changing voltage and current in fine increments according to the device’s request.
| QC Version | Release Date | Max Power | Voltage Range | Key Features | USB PD Compatibility |
|---|---|---|---|---|---|
| 1.0 | 2013 | 10W | Max 6.3V | Automatic determination of optimal current for each smartphone | None |
| 2.0 | 2014 | 18W (A) / 60W (B) | 5V/9V/12V/20V | Supports 3-stage voltage switching and dual charging※2 | None |
| 3.0 | 2015–2016 | 36W | 3.2–20V (200mV increments) | Suppress heat by adjusting voltage in fine increments | None |
| 4 / 4+ | 2016–2017 | 100W | QC: 3.6–20V / PD: 5V, 9V, PPS | PD Compatible | Yes |
| 5 | 2020 | Over 100W | 3.3V–20V+ | USB PD PPS compatible, enhanced thermal management, full backward compatibility | Yes (via PPS) |
※2 Dual Charging = Simultaneous charging via two independent power circuits to shorten charging time.
Ms.ガジェットCheck the standards supported by your device before choosing.
Mr.ガジェットThere are also power banks that support wireless charging or other standards not mentioned here, so if there are specific standards you need, please be sure to check those thoroughly as well!
Input Level
- Charging speed of the power bank itself: Check the time it takes to charge the power bank itself.
- Input port type: Confirm whether the connector of the cable used for charging is USB Type-C or Micro USB.
It is often overlooked, but “Input,” which relates to the charging speed of the power bank itself, is also important.
The higher the input, the shorter the charging time for the battery unit.
Choosing a model with a USB Type-C port that supports fast charging standards like PD or QC is convenient as the unit itself can be charged in a short time.
Mr.ガジェットThis is a point that is often overlooked, but it is important!
Especially as the capacity increases, the charging time tends to lengthen, so caution is required.
Ms.ガジェットAlso, make sure to choose a Type-C input port!
Those that still use Micro USB are out of the question, so please do not choose them under any circumstances!
Types and Number of Ports
- Need for simultaneous charging: Choose the number of ports based on the number of devices you want to charge at the same time.
- Max output of each port: Confirm if the maximum output from each port meets your needs.
- Performance during charging: Check how output is distributed when multiple ports are used and whether each port can provide maximum output independently.
- Compatibility with devices: Confirm the types of ports required for your devices (USB Type-A, USB Type-C, etc.).
Ports are the terminals used to connect devices to the power bank.
The type of port (USB Type-A, Type-C, etc.) and the number of ports determine which devices and how many can be charged simultaneously.
Choose the number of ports according to the number of devices you wish to charge at once.
For example, if you want to charge earphones or portable game consoles along with your smartphone, having at least two ports is convenient.
Currently, the most common are USB Type-A and USB Type-C ports.
Type-C ports are particularly recommended as they are reversible and many support high-output charging like PD.
| Terminal Name | Shape Description | Main Features | Input/Output | Device Examples |
|---|---|---|---|---|
| USB Type-A | Rectangular | Traditional standard terminal | Output only | Older chargers, PC ports |
| USB Type-C | Symmetrical oval | Reversible, supports high-speed data transfer and high output (USB PD) | Both Input/Output | Latest smartphones, tablets, laptops, earphone cases, etc. |
| Lightning | Apple proprietary slim shape | Apple proprietary terminal | Mainly Input | iPhone (14 and earlier), specific iPads, AirPods cases, etc. |
| Micro USB Type-B | Small trapezoidal shape | Former standard for small devices, still used in some cases | Input only | Older Android smartphones, power banks, Bluetooth speakers, etc. |
Ms.ガジェットIf there are many ports, can they all fast-charge at the same time?
Mr.ガジェットEven with more ports, the maximum output of each port may decrease when used simultaneously.
In cases where there are multiple ports, using all of them simultaneously often results in the total output being divided, which can lower the maximum output of each individual port. It is advisable to check the specifications for this detail.
It is important to choose a model with the necessary types and number of ports according to your device configuration.
Main Body Size and Weight
- Ease of portability: For daily carrying, choose a slim and lightweight model. Consider a size that fits easily in bags or pockets.
- Balance with capacity: High-capacity models tend to be heavier and larger. Choose the most compact model possible with the minimum required capacity.
- When will you use it?: For outdoor activities or long-term travel, it is desirable to choose a high-capacity, durable model even if it is slightly larger.
The size and weight of the power bank are important factors that directly affect portability.
Generally, the larger the capacity, the heavier and larger the unit tends to be.
Ms.ガジェットI want to carry it daily; what size should I use as a guideline?
Mr.ガジェットFor daily use, I recommend the 10000mAh class, which has a good balance between capacity and size.
If you often carry it in a bag or pocket daily, it’s best to choose a model with a good balance of capacity, size, and weight.
On the other hand, if you plan to keep it in your home or car for emergencies, or if you absolutely need a large capacity for long trips, you might opt for a larger, high-capacity model.
Recently, many products are becoming more compact even with the same capacity, so be sure to check the size carefully.
Safety (PSE Mark) Above All Else
- Protection features: Confirm whether features protecting the device from overcharging, over-discharging, overheating, and short-circuiting are provided. These are essential for safe battery use.
- Certification marks: Check for marks indicating the product complies with safety standards, such as the PSE mark (Japan), CE mark (Europe), or FCC certification (USA).
- Reliable brands: Purchase from reputable manufacturers or brands. Refer to reviews and ratings to check safety feedback from other users.
Safety is the most, most important factor in choosing a power bank.
Power banks sold in Japan are required by the Electrical Appliances and Materials Safety Act to display the PSE mark, which indicates compliance with national safety standards.
I want everyone to always choose products that display this PSE mark.
| Safety Checklist | Why it’s Important | How to Confirm |
|---|---|---|
| Presence of PSE Mark | Proof of compliance with Japanese safety standards; reduces risks like fire accidents | On the product unit or package |
| Protection features (Overcharge, over-discharge, overheat, short circuit, etc.) | Prevents battery degradation, abnormal heating, or fire | Product specs, description |
| Purchase from reliable manufacturers/retailers | Quality control is solid, and support can be expected | Official manufacturer site, trusted retailers |
Ms.ガジェットIs there any other way to confirm safety besides the PSE mark?
Mr.ガジェットConfirming that protection features like overcharging or overheating protection are included and choosing from reliable manufacturers also leads to peace of mind.
Lithium-ion batteries can cause heating or fire if used incorrectly or if there is a problem with the product.
You should absolutely avoid products from unknown manufacturers that lack the PSE mark.
When disposing of used batteries, products from manufacturers that are not members of **JBRC** (an organization promoting the collection and recycling of batteries, which includes many unknown Amazon brands) may reportedly be rejected by collection boxes at electronics retailers.
Mr.ガジェットI recommend purchasing from major manufacturers that are members of JBRC (Anker, CIO, Elecom, Buffalo, etc.)!
Additionally, it is even safer to confirm whether protection features against overcharging, over-discharging, overheating, and short-circuiting are provided.
It is recommended to purchase from reliable manufacturers.
Mr.ガジェットFor your safety, please always check for the presence of the PSE mark.
Ms.ガジェットThis is a point where you absolutely cannot compromise.
Get a Safe and Secure Power Bank
In this article, I explained important points so that you won’t get lost when choosing a power bank.
In particular, safety is a criterion that can never be compromised to protect your digital life.
- Guideline for required capacity (mAh)
- Output (W/A) and fast charging standards (PD/QC) appropriate for the device
- Desired size and weight for portability
- Types and number of ports for the devices you want to connect
By keeping these points in mind, you can find a safe and secure power bank that’s perfect for you.
Please use the knowledge you’ve gained today to find the ideal one.
Frequently Asked Questions (FAQ)
- What is pass-through charging?
-
Pass-through charging is a feature that allows you to charge the power bank itself from an outlet while simultaneously charging a connected device, such as a smartphone.
With this feature, if you connect the power bank and smartphone before going to sleep at home, both the power bank and the smartphone will be fully charged by morning, which is very convenient.
However, as power banks tend to generate more heat during pass-through charging, please pay attention to safety during use. - How long does it take to charge the power bank itself?
-
The time required to charge the power bank itself varies greatly depending on its capacity and the magnitude of the power bank’s “input.”
The higher the input wattage (W), the shorter the time it takes to complete the charge. - What do terms like W (Watt) and A (Ampere) seen in power bank specs mean?
-
The W (Watt), A (Ampere), V (Volt), and mAh (milliampere-hour) often listed in power bank specs have the following meanings:
- V (Volt): Voltage. The force that pushes electricity.
- A (Ampere): Current. The amount of electricity flowing.
- W (Watt): Power. Calculated as Voltage (V) × Current (A), it directly affects charging speed. Higher numbers mean faster charging.
- mAh (milliampere-hour): Capacity. The total amount of electricity stored in the battery. Higher numbers mean you can charge devices more times.
To use an analogy, V is the water pressure in a pipe, A is the amount of water flowing, W is the total supply capacity of the water pipe, and mAh is the capacity of the storage tank.
It is important to choose a power bank with specs that match the power (W and A) your device requires and the number of times (mAh) you want to charge it.
Thank you for reading to the end!
- The views expressed in this article are the independent opinions of this website.
- Unless otherwise stated, product prices and information are current at the time of writing.
- Please note that we cannot be held responsible for any errors or omissions. Thank you for your understanding.
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