What Is a Power Bank? Benefits, Buying Tips & Top Picks for 2025

If you’ve ever had your phone die at the worst possible moment, you know how frustrating it can be. That’s where a power bank comes in handy. But what is a power bank exactly, and how does it work?

In this guide, you’ll learn everything you need to know, from how power banks function and the benefits they bring to what to look for when buying one and the top models worth checking out this year. By the end, you’ll be able to choose the right power bank with confidence and keep your devices powered up wherever life takes you.

What Is a Power Bank?

A power bank, often called a portable charger, is a rechargeable battery pack that lets you charge electronics like phones, tablets, earbuds, and even laptops when you don’t have access to a wall outlet.

These handy gadgets store energy in internal battery cells and release it when you plug in a device through a charging cable. Most connect through USB-A or USB-C, and some newer models also support wireless charging.

They come in a wide range of sizes and capacities. Whether you’re travelling, hiking in the mountains, or simply out and about, power banks give you the freedom to stay connected anywhere.

How Does a Power Bank Work?

Now that you know what a power bank charger is, let’s dive deeper into how it works. A power bank is basically a rechargeable battery with smart circuitry that lets it safely store and deliver power to your devices:

1. Storing energy: Inside are lithium-ion or lithium-polymer cells. When you charge the power bank from a wall outlet, these cells store the energy for later use.
2. Power management: A built-in control circuit board manages how the battery charges and discharges, making sure it doesn’t overcharge, overheat, or deliver unsafe voltage to your devices. It also converts the battery’s native voltage (usually around 3.7V) into standard 5V USB outputs (or higher, with fast charging) that your phone or tablet needs.
3. Charging your devices: When you plug in a phone or tablet, the power bank transfers stored energy in a controlled, efficient way. Standard output is 5V, but fast-charging models can deliver 9V, 12V, or more if your device supports it.
4. Extra Features: LED indicators show remaining power, and some models add multiple ports, exact percentage displays, two-way fast charging, or wireless charging.

Benefits of a Power Bank

Power banks have become one of the handiest tech accessories you can carry. Here’s why:

• Stay powered anywhere: The biggest perk is obvious: you don’t have to hunt for an outlet. Whether you’re travelling, commuting, going on camping trips, or just out for the day, a power bank ensures your devices stay charged and ready when you need them most.
• Fast, flexible charging:Most modern power banks use USB-C and USB-PD for faster speeds and compatibility with a wide range of devices, including laptops.
• Charge more than one device: Many models include multiple USB-C and USB-A ports, so you can top up your phone, tablet, earbuds, or a friend’s device at the same time, as long as the bank can support the load.
• Compact and travel-friendly: Despite their capacity, most power banks are lightweight and easy to slip into a bag or a pocket, making them practical for daily use.

How to Choose the Right Power Bank

Not every power bank is built for the same purpose. Some are made for slipping in your pocket for emergencies, while others are designed to power laptops through a long workday. Here’s what you should pay attention to before you pick one.

Capacity: mAh vs. Wh

Think first about how much battery backup you really need. A slim 5,000 mAh pack is enough for a quick charge during the day. Move up to 10,000 mAh and you can usually recharge your phone one or two times.

Around 20,000 mAh is where you’ll have the freedom to top up a phone, a tablet, or even a handheld console without worry. Beyond that, you’re in laptop-grade territory, best suited for heavy users who need to keep multiple devices alive.

When it comes to air travel, airlines don’t care about milliamp-hours (mAh)—they go by watt-hours (Wh). Most follow International Air Transport Association (IATA) guidelines, which CATSA and other agencies also adopt:

• Up to 100 Wh (≈27,000 mAh at 3.7V):allowed in carry-on luggage without restrictions
• 101–160 Wh:typically allowed with prior airline approval, often with a limit of two units
• Over 160 Wh:not permitted on passenger flights

If the label only shows mAh, you can convert using:

Wh = (mAh × V) ÷ 1000

where V is the nominal cell voltage (about 3.7V for most lithium cells). A 20,000 mAh bank, for example, works out to roughly 74 Wh, well under the 100 Wh threshold.

Charging Output and Fast Standards

A decent power bank should do more than just trickle power into your phone. Aim for one with USB-C ports that support Power Delivery (PD), today’s standard for fast, efficient charging. For everyday phone use, a power output in the 20–30W range is usually enough.

For tablets, laptops, or multiple devices at once, you’ll want something stronger. PD 3.0 supports up to 100W, while PD 3.1 increases the ceiling to 240W. In practice, consumer power banks usually max out around 140W, which is still enough to handle most demanding laptops.

Some devices may use other fast charging standards. Samsung, for example, uses PPS (Programmable Power Supply). If you own a Galaxy S24 Ultra, Z Fold, or another device that supports 45 W Super Fast Charging 2.0, make sure the bank lists PD 3.0 with PPS at 45W, otherwise you won’t get full speed.

How Quickly It Recharges

It’s easy to overlook how long a power bank itself takes to fill back up. Models that accept 30W+ USB-C input can go from empty to full in under two hours with the right wall charger. Lower-rated models may need several hours, which can be frustrating if you rely on your bank daily.

Ports and Cables

USB-C has become the universal standard, so look for power banks with multiple USB-C ports. A USB-A port can still be handy for older accessories, but it shouldn’t be your priority. Some models also include built-in cables, which save space and reduce the risk of forgetting cords.

Weight and Build

More capacity usually means more bulk. If you want something pocket-friendly, stay under 250 g. For backpack use, weight isn’t as critical, but durability is. A tough case with reinforced corners will better handle drops, scratches, and the wear of travel.

Safety and Standards

Battery safety is important. Certifications like UL 2056 confirm that a power bank has been tested for issues such as fire risk, over-current, and accurate capacity labeling. If you travel abroad, check that it meets UN 38.3 standards, which ensure compliance with international lithium battery transport rules. These marks of quality aren’t just nice to have—they can prevent airport hassles and give you peace of mind.

Wireless Options

Finally, think about convenience features. If you’re using an iPhone or other MagSafe-compatible device, a magnetic wireless pack can snap on and charge without cables. The latest Qi2 standard aligns the coils with magnets, making wireless charging more efficient and raising speeds to 15W—double the older Qi limit of 7.5W.

Best Power Banks in 2025

The latest power bank models bring faster charging speeds, better safety systems, and smarter designs that make them easier to use every day. Here are four of Anker’s standouts in 2025:

Anker MagGo Power Bank (5K, Slim)

The Anker MagGo Power Bank (5K, Slim) is all about portability. With 5,000 mAh capacity, it’s perfect for quick top-ups during the day. It magnetically snaps onto MagSafe-compatible iPhones and delivers up to 15W Qi2-certified wireless charging, so you can power up without hunting for a cable.

A 20W USB-C port is also available when you need a faster wired charge. At just 8.6 mm thin and 122 g, it’s lighter than most phones and slides easily into a pocket or purse. Thanks to its graphene cooling system, dual NTC sensors, and smart charging optimization, it runs cooler and safer while charging.

Best for: Everyday iPhone users who want the lightest, most portable bank for emergencies and quick snap-on wireless charging.

What’s good:

• 15 W Qi2 wireless chargingfor fast, aligned top-ups
• 5,000 mAh capacityin a super-slim, 122 g body
• 20W USB-C portfor wired flexibility
• Graphene cooling + NTC sensorsfor safer operation

Anker MagGo Power Bank (10K, Slim)

Need more backup? The Anker MagGo Power Bank (10K, Slim) doubles the capacity to 10,000 mAh while staying sleek enough for everyday use. It offers 15W Qi2-certified wireless charging plus a USB-C port with up to 30W PD output for faster wired charging. The bank itself also recharges at up to 30W, meaning you can quickly top it up with a compatible wall adapter.

At around 200 g and just under 15 mm thick, it still fits neatly into a work bag or purse. With Anker’s ActiveShield 2.0, the device checks its temperature millions of times per day, keeping both your phone and the power bank safe from overheating.

Best for: Users who need a slim, everyday power bank that can handle 2 full phone charges and both wired and wireless fast charging.

What’s good:

• 10,000 mAh capacity(about two full phone charges)
• 30W USB-C PD output + 30W inputfor fast charging and refills
• 15 W Qi2-certified wireless charging
• ActiveShield 2.0 safety systemwith advanced thermal monitoring
• Compact, slim design (~200 g)
• Matte UV finish, metal frame, and aerogel thermal insulation for comfort

Anker Nano Power Bank (10K, 45W, Built-in Retractable USB-C Cable)

The Anker Nano Power Bank (10K, 45W, Built-in Retractable USB-C Cable) is made for speed and convenience. With 10,000 mAh capacity and 45W USB-C output, it can charge not just phones and tablets but also many thin-and-light laptops. It also supports Samsung Super Fast Charging 2.0 (PPS, up to 45W), so Galaxy owners get full performance.

Its standout feature is the built-in retractable 0.7 m USB-C InstaCord, which means no extra cables to carry. A smart display shows real-time charging status, and the bank itself refuels at up to 30W with a PD charger.

Safety is handled by ActiveShield 3.0, which constantly monitors temperature. With two USB-C outputs (the built-in cable + a port) plus a USB-A, you can charge up to three devices at once when needed.

Best for: USB-C device owners who want fast charging (including Samsung 45W support) and the convenience of a built-in cable.

What’s good:

• 45W USB-C outputwith Samsung Super Fast Charging 2.0 (PPS) support
• Convenient built-in retractable USB-C cable (0.7 m)tested for durability
• 30W USB-C inputfor quick recharges
• Smart displaywith live input/output and battery level
• ActiveShield 3.0 thermal protection
• Three outputs(2× USB-C, 1× USB-A) for multiple devices

Anker 737 Power Bank (PowerCore 24K)

For those who need serious power, the Anker 737 Power Bank delivers with 24,000 mAh capacity and 140W PD 3.1 two-way charging. It can comfortably recharge laptops, tablets, and phones, making it a true all-in-one solution. With two USB-C ports and one USB-A, you can power multiple devices at once, and the smart digital display gives you real-time power flow and time-to-full estimates.

At about 630 g, it’s heavier than pocket-sized models but still compact enough to fit in a backpack or work bag. This is the powerhouse you reach for when you need to keep everything—from an Ultrabook to earbuds—running smoothly.

Best for: Power users who need laptop-level charging plus the ability to run several devices at once.

What’s good:

• 140 W PD 3.1 bi-directional fast charging
• 24,000 mAh capacity(about 4–5 phone charges)
• Three ports(2× USB-C, 1× USB-A)
• Smart digital displaywith power/time info
• Solid, durable build (~630 g)

Tips to Prolong Your Power Bank’s Life

A good power bank should last you years if you treat it well. These habits will help keep its battery healthy and reliable:

• Avoid full drains and overcharging:Lithium-ion cells perform best when kept between about 20–80% charge. Don’t let your bank sit at 0% for long periods, and unplug it once it’s full.
• Use quality chargers and cables:Always recharge with a reputable wall adapter and certified cables. Low-quality accessories can shorten battery life or damage internal circuits.
• Keep it cool:Heat accelerates battery wear. Avoid leaving your power bank in hot cars, direct sunlight, or tightly packed bags where it can overheat while charging.
• Recharge regularly:Even if you don’t use it often, top it up every few months to keep the cells active and prevent deep discharge.
• Store properly:For long-term storage, keep the battery at around half charge (40–60%) in a cool, dry place.

Conclusion

Now you know what is a power bank, how it works, and how to choose and care for one. The right portable charger can keep your phone, tablet, or laptop powered up wherever you go, without the stress of a dying battery. Brands like Anker make reliable, certified options that balance capacity, speed, and safety. Whether you want a pocket-friendly wireless battery pack that snaps on or a high-capacity 20,000mAh+ multi-port power bank for busy days, you’ll find your perfect match at Anker.

FAQs

What is the purpose of a power bank?

A power bank is a portable battery pack that lets you charge your devices when you’re away from a wall outlet. It’s especially handy during travel, long commutes, emergencies, or outdoor activities where access to power is limited. With one in your bag, you can keep your phone, tablet, earbuds, or even laptops powered up and ready to use whenever you need them.

What are the disadvantages of a power bank?

Power banks are convenient, but they’re not perfect. They add extra weight to your bag, need time to recharge, and low-quality ones may wear out quickly and lack safety features, posing risks like overheating. Larger-capacity models can be bulky, while smaller ones may only offer a single charge. It’s important to choose a reliable power bank that balances portability and performance to suit your needs.

Do power banks need to be charged?

Yes, power banks must be charged before they can recharge your devices. They work like a reusable battery pack—once used, they need to be “refilled.” Charging frequency depends on the size of the power bank and how often you use it, but keeping it topped up ensures it’s ready when you need it.

How long will a power bank charge last?

A power bank can typically hold a charge for up to six months, though this depends on quality, usage, and storage conditions. High-quality models may only lose 5–10% of their stored power per month, while lower-quality ones may drain much faster. To prolong standby life, store it in a cool, dry place and recharge it to about 50% every few months.