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How to Choose a Power Bank

How to Choose a Power Bank

On the face of it, power banks and portable chargers are super simple devices. It’s just a big battery, right? Err, yeah actually, that is right! With that said, there are a ton of different ports, capacities, and technologies to consider if you and your devices are going to make the most of their power. 

As the world’s most well-known power bank brand, you can trust our advice. And if you don’t end up choosing  Anker, that’s cool! We’re just spreading the charging love. 

This is a complete beginner’s guide so feel free to jump to other sections if you’re already up to speed on some stuff.

Jargon Buster

There are 3 main specs that you’ll need to be familiar with when you’re power bank shopping.

Capacity - This is how much juice the power bank holds, usually measured in milliamp hours (mAh). 

Input - This is the amount of power required to recharge the power bank itself.

Output - This is the amount of power the charger can give to other devices.

Port  - This is the type of socket or connector. A lot of power banks are now recharged via a USB-C port, but they can often give power out via USB-A (the traditional style USB plug) too.

Size Vs Power

As with everything in life, your power bank is a compromise. You’ll have to balance how much power you want with how big of a brick you want to carry around with you. A pocket-size charger isn’t going to keep you going through a week in the wilderness, but a big slab of plastic isn’t going to look great dangling out of your purse in the bar. 

Pocket Chargers (3000-9000 mAh) will get you one, or maybe two, full charges for your phone so they’re great for a night away. They also come in hundreds of colors, shapes, and sizes, so you can style it out or keep it hidden. Generally, at this size, you’ll also be able to give your tablet a slow charge but it might not reach 100%—laptops and anything bigger are out of the question.

Medium Chargers  (9000-15000 mAh) will get you at least two or three charges for your phone or one for a tablet. They’re usually too big and heavy for a pocket so you’ll have to carry them in a bag if you’re on the go. Depending on the power bank’s output, you’ll potentially be able to start charging laptops in this range. 

Big Chargers  (15000 mAh+) are basically unlimited in how many charges they can give and what devices they can power. These power banks can keep your phone charged for a week or more and can power anything from laptops to well... anything! Would you like a cold drink from my fridge powered by  PowerHouse?

How Many Charges Can I Get?

Almost all rechargeable batteries (including power banks and the batteries in your phone and tablet) are measured in milliamp hours (mAh). For example, iPhone 12 has a 2,815 mAh battery. 

If my phone has a 2,815mAh capacity battery and my power bank also has a 2,815mAh capacity, it should charge my phone exactly once, right? WRONG. If only life were so simple… The process of transferring the charge from one battery to another requires energy. With most power banks you can expect to lose up to around 30% of the total capacity just pushing the charge from one side to the other (higher quality power banks will lose less).

So if I have a 10,000mAh power bank, only around 7,000mAh of that is going to be usable. You’d get just under 3 charges for an iPhone 12.

Input and Output

Power banks and phones are smart enough to decide exactly how much power should be given and received. 

Say, for example, your phone has an input of 5 volts and 2 amps (5V/2A). If you have a power bank that has the same output as that phone’s input then it’ll recharge at its fastest possible speed. If the output of your power bank is lower than 5V/2A, then it’ll recharge just fine but slower. If the power bank’s output is higher than 5V/2A then you’ll charge at full speed and the extra power is no risk to your phone or charger.

The important thing to remember is that if you want the fastest possible charge, then match the input and output. But the worst that can happen if you don’t is your devices or power bank might charge slowly.

What About Fast Charging?

Once upon a time, there was only a single fast-charging technology:  Qualcomm Quick Charge. Nowadays almost all Android phones have their own proprietary fast-charging hardware. These brands don’t like to share their secrets, so unless your charger or power bank has their exclusive hardware, it won’t charge at full speed (even if the input and output are completely matched). So if you want a power bank that charges your phone at its maximum possible speed, you’ll probably need to get a power bank directly from the same manufacturer. 

If they don’t make one, you’re going to be charging lots of different devices, or you don’t want to pay a premium, any power bank will still charge your phone perfectly well (albeit not at maximum speed).

What Should I Get for My Phone?

Now, we can make some recommendations for power banks for your specific phone. Remember, you don’t have to buy  Anker, that’s just our recommendation because we think they’re the best. A charger with the same capacity and output ports will work for you.

For iPhone and Android Phones




PowerCore 5000

The super-compact portable charger gives your phone at least one complete charge, making it perfect for use at home or on the go.

PowerCore Slim 10000 PD (USB-C)

The slimmest and lightest 10,000 mAh portable charger provides around 2 charges for your phone.

 PowerCore III Elite 25600 (USB-C)

Known for its high capacity and incredible speed, this portable charger will get your phone anywhere between 5 and 8 charges.

For Tablet & Laptop



PowerCore III Sense 10K (USB-C)

This 10,000 mAh portable charger has enough power to take a 2018 iPad Pro from empty to full once, adding 10+ hours onto your tablet. 

PowerCore+ 26800 PD 45W (USB-C)

Ultra-high 26,800 mAh capacity is capable of powering three devices simultaneously to keep you going for days. Equipped with USB-C Power Delivery, get one full charge for your MacBook laptop.

Something else to consider is the cable you use with your phone. If you charge with a USB-C cable then it would be worth investing in a portable charger that also recharges via USB-C, that way you’ll only need to carry one cable. Unfortunately, iPhones still use Lightning connectors which is proprietary Apple hardware so you won’t find a power bank that can recharge with that connector (sigh).

Wireless and Magnetic Chargers

After the iPhone 12 was released in 2020 with MagSafe, power banks began appearing that magnetically stick to your phone. They’re a great option as long as you’re using the latest generation of iPhone. Anker 622 Magnetic Battery (MagGo) fits the bill perfectly, and if you want to see more from our full range of magnetic wireless chargers for iPhone, just click here.

If you’re not an iPhone user but still loving the convenience of wireless charging,  PowerCore III 10K Wireless is a great choice! That can be wirelessly recharged and wirelessly charge your devices.

Remember though, wireless charging is less efficient than charging with a cable so you’ll lose extra capacity during the power transfer.

Wrap Up

Our power banks are consistently rated the best in the world, so you can trust us when it comes to anything to do with charging. If you still have questions then feel free to browse our  store, or visit our  community and get help from other experts.

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