What Is a Power Bank?

(Last Updated On: March 15, 2024)

Power banks are versatile gadgets with numerous applications. Originally gaining popularity for charging smartphones, the power banks of today can power everything from vape pens and Kindles to computers, often simultaneously.

Sound like something that would be helpful in your life? Let’s take a deeper look at what a power bank is and how to find the best one for your devices.

What Is a Power Bank?

You may also hear power banks called portable chargers, and that gives you a good basic idea of what they do. A power bank is basically a secondary battery you can charge up and take with you. They allow you to recharge devices like phones and tablets even when you’re not near an outlet.

Power banks come in a variety of sizes and capacities. Typically the larger the power bank is, the more power it can hold. Most pocket-sized power banks are designed for charging things like smartphones, portable speakers, and other small devices, while bigger models can even recharge laptops.

what is a power bank
These things are quite powerful

Most power banks can be recharged through a wall outlet. You can also find power banks that recharge via solar panels. These models are ideal for hiking and camping since you can recharge your devices even when you’re far from an outlet.

Types of Power Banks

There are a lot of options out there when it comes to portable chargers. You can differentiate them based on three main criteria: the size of the charger, the type of battery, and how the charger receives and distributes power.

Power Bank Size

Size-wise, power banks come in two main categories: Mini Portable Chargers and High-Capacity Chargers. Compact mini chargers often weigh less than a pound and are small enough to fit into your pants pocket. These are some of the most useful and popular chargers on the market since they’re so easy to take anywhere. The downside of mini chargers is their comparatively low capacity.

High Capacity chargers can provide 20,000mAh or more between charges. Many offer multiple charging ports so you can plug in all your devices at once. They typically also charge devices faster than mini chargers because of their higher capacity.

Type of Battery

There are 2 battery styles you’ll see employed in most power banks:

  • Lithium-ion batteries. Lithium-ion (or Li-ion) batteries are generally the more affordable option. They also tend to have a lower capacity and are found in many mini portable chargers.
  • Lithium-polymer batteries. Lithium-polymer cells can be larger than Li-ion batteries. This gives them a higher capacity and also prevents them from suffering the memory effect that lowers their capacity over time. On the flip side, they tend to cost more.

Charging Style

This is where you’ll see the most variety and innovation in the power bank market. Some of the options you’ll find include:

  • Universal Power Bank. The most common form of the portable charger, universal power banks are designed to charge a variety of devices. They’re available in many sizes and configurations and can be recharged through a wall outlet. Most high-capacity power banks are of this style.
  • Charging Phone Cases. These devices integrate a charger into a case for your smartphone. This makes re-charging easy and guarantees you’ll never forget your power bank. Though they’re convenient, they’re limited in use, only working for smartphones that fit into the case.
  • Solar Power Bank. These chargers are equipped with built-in solar panels that capture the sun’s energy, converting it into power for your devices. Their main advantage is that they free you from reliance on an outlet. Most also come with a cord for charging when there’s no access to sunlight. The disadvantage of solar power banks is that they’re often slow to charge.
  • Smart Power Bank. This is a variant of the universal power bank above. A power bank with smart technology recognizes the type of device you’ve plugged in, identifies the voltage, and determines the best level of charge. Smart power banks are more efficient, often charging devices more quickly without the risk of damage.
  • Quick Charge Power Banks. These power banks are designed to provide a higher rate of charge. This charges your devices up to 75% faster than traditional power banks. You do have to use more caution with a quick charging bank to avoid damage to your device’s battery.

How Long Does a Power Bank Last?

If you’re wondering how much power you can get from a power bank between charges, that depends on the capacity. This is measured in milli-Ampere-hours or mAh. The higher the mAh rating of the portable charger, the more devices you can charge with it before you need to plug it in.

Both li-ion and polymer batteries have a low self-discharge rate. This means that most power banks don’t lose much of their charge in storage. Most can sit for 6 months or more with minimal charge loss.

When it comes to long-term durability, power banks typically have a lower lifespan than other device batteries. You can expect a power bank to last through about 500 discharge cycles. For most users, that equates to around 2-3 years.

Power Bank Technology: How Does a Power Bank Work?

In the most basic terms, a power bank is a battery that receives energy from one source (e.g. a wall outlet or solar panel), stores it, and delivers it to other devices as needed.

Power banks are usually very simple in their design. There is typically one input power port, where you plug in the charging cable. On the other side are one or more output ports, often USB or Type-C, though you can find power banks with traditional 3-pronged outlets.

The power bank holds onto its power until a device is plugged into one of the output ports. Most modern power banks surround this battery with sophisticated electronics for regulating the charge, even if they’re not considered a “smart power bank”. This can include safety protections against over-charging and over-voltage.

So How Do I Choose the Right Power Bank?

As you can see, power banks are very useful little devices, especially as more and more of our lives are built around electronics. When you’re buying a power bank, start by identifying which devices you’ll want to charge and how much power they need.

Devices have a mAh rating, as well. A good rule of thumb is to match the mAh rating of your device with the portable charger you buy. If you want to charge a variety of devices, a smart power bank or universal power bank is typically your best bet.

Bonus: check out our guide on how to change a car battery!

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