Which power bank should you buy? How to choose by mAh, flight rules and MagSafe
How many mAh do I need, and can I take it on a plane? I hear those two questions at the counter every week, usually just before a holiday. Right after comes the third: is MagSafe worth it, or is a cable more practical after all? The right power bank depends on how you use it, and most people skip over that too quickly.
I’m Job from ThePhoneLab. My colleague Jeffrey, who started as a repair specialist in 2015 and now handles our purchasing together with Zohra, selected our power banks based on ten years of seeing what goes wrong at the repair counter. Below are my answers, so you know right away which power bank suits you.
In this blog, we discuss:
- How many mAh do you need?
- Which power bank can you take on a plane?
- MagSafe power bank or a power bank with a cable?
- Fast charging from a power bank: where it goes wrong
- A power bank in your emergency kit
- Which power bank do you choose?
How many mAh do you need?
For a day on the go, 5,000 mAh is enough for about one top-up, 10,000 mAh for a good one and a half to two full charges, and 20,000 mAh for several charges or a tablet and a light laptop. The mAh on the packaging is the capacity of the cells, but because of conversion loss and voltage differences, only 60 to 70 percent of it ends up in your phone.
Jeffrey explains in his tip in the shop why he selects on honest capacity: “You often read 10,000 mAh on the packaging, but in practice, you rarely fully charge a phone twice with it.” So don’t count on the packaging, but on what you need:
- 5,000 mAh: in practice, one top-up. Weighs next to nothing, fits in your jacket pocket.
- 10,000 mAh: a good one and a half to two top-ups. The size most customers choose.
- 20,000 mAh: three to four times, or a tablet and a light laptop. You’ll feel that one in your bag.
His most important advice: “The best power bank is one you actually take with you.” A heavy 20,000 mAh that sits in a drawer at home won’t help you.
How often also depends on your phone’s battery, which varies a lot by model. An example: of 10,000 mAh, about 6,500 mAh ends up in your phone. That charges a battery of around 3,500 mAh almost twice, and a large one of around 5,000 mAh (Pro Max, Galaxy Ultra) just over once.
Charging wirelessly via MagSafe always loses extra: it is less efficient than a cable, because part of the energy leaks away as heat. So count on fewer charges.
What does mAh actually mean? It stands for milliampere-hour: how much charge a battery can store. Think of your power bank as a jerry can and your phone as the tank of your car: the more litres in the jerry can, the more often you can refill the tank.
Exactly how often also depends on the tank. From the same jerry can, you can fill a small tank more often than a large one. And you always spill a little when pouring: with a funnel (the cable) only a bit, without a funnel (wireless) more.
Which power bank can you take on a plane?
A power bank may only go in your hand luggage, never in your checked baggage, and up to 100 watt-hours (Wh) without permission. Above that, up to 160 Wh, you need permission from the airline; more than 160 Wh is not allowed. All our power banks are well below that limit: 10,000 mAh is about 37 Wh and 20,000 mAh about 74 Wh.
To calculate it yourself: mAh divided by 1,000, times 3.7 volts. So 27,000 mAh is around 100 Wh, the practical upper limit for flying.
Make sure the capacity is legible on your power bank; at security, a power bank without a label can be refused. And more and more airlines ban using or charging a power bank during the flight, or want it within reach instead of in the overhead bin. Check your airline’s rules before you leave.
MagSafe power bank or a power bank with a cable?
A MagSafe power bank snaps magnetically onto the back of your iPhone and charges without a cable, while you keep calling or navigating. A power bank with a cable charges faster, works with any phone and can often charge several devices at once. With an iPhone 12 or newer (except the 16e) or a case with a magnetic ring, MagSafe is worth it. With a Samsung without a magnetic case, or if you also charge a tablet or laptop, choose a cable.
Our MagSafe power banks of 5,000 and 10,000 mAh work via the Qi2 standard, with a magnetic ring that snaps onto any MagSafe iPhone. They charge wirelessly, but also by cable via USB-C, so you always have the fastest option.
To be fair: it is not Apple-certified 15-watt MagSafe charging, but a stable wireless connection that doesn’t easily come loose. One condition: your case needs magnets, otherwise the power bank will be on the ground after your first step. You can read why in What is MagSafe?
Power bank with MagSafe
5,000 or 10,000 mAh, snaps magnetically onto your iPhone and also charges by cable via USB-C. Four lights show how much charge is left.
Fast charging from a power bank: where it goes wrong
A good power bank with Power Delivery charges your phone almost as fast as a fast charger in the wall socket, and neatly scales back as soon as your phone signals it has had enough. That scaling back is exactly what goes wrong most often with cheap power banks. Jeffrey sees the consequences at the counter: batteries that wear out much sooner than they should, because they were charged day in, day out with unstable current from a cheap power bank.
So look for four things:
- Power Delivery via USB-C for fast charging iPhones and modern Android phones.
- A good cable. A power bank never charges faster than the cable allows; use a cable that supports fast charging.
- Protection against overheating, short circuits, overcharging and deep discharge. A power bank sits close to your body: in your pocket, in your bag, on your bedside table.
- Lights or a display, so you can see how much charge is left and don’t head out with an empty power bank.
If you want to know which adapter and cable go with your iPhone, read my blog Which charger do you need for your iPhone?
USB-C to USB-C charging cable
Fast charging up to 60 watts with Power Delivery, reinforced connectors and a sleeve that doesn't kink easily.
A power bank in your emergency kit
The Dutch government advises every household to have an emergency kit to get through the first 72 hours, including a battery-operated radio and your mobile with a charged power bank. If the power goes out, your phone is your flashlight and, as long as the network works, your contact with the outside world. A 10,000 mAh is a good minimum for that; 20,000 mAh gives you three to four full charges, enough to keep a family reachable for a day or two.
A power bank in the cupboard slowly loses charge. Keep a daily one at around half, but keep the one in your emergency kit full: set a reminder in your calendar every three months and top it up. Add a cable for every phone in the house: USB-C to USB-C for newer phones, USB-C to Lightning for an older iPhone.
Power bank 20,000 mAh
Four ports and a display with the exact percentage. Enough for several charges, and allowed in your hand luggage.
Which power bank do you choose?
It comes down to three questions: how much do you want to charge, do you want a cable or not, and will you really take it with you? Answer honestly and the choice makes itself. Say yes to the laptop or no to MagSafe, and you end up with a cable version; want it in your pocket every day, and light beats big:
- A light spare for your pocket, with a MagSafe iPhone: the 5,000 mAh with MagSafe.
- One power bank for everything, without a cable: the 10,000 mAh with MagSafe and USB-C.
- A Samsung or Android without a magnetic case, or two devices at once: the 10,000 mAh with USB-C and USB-A.
- Lots of travel, camping or topping up your laptop: the 20,000 mAh with four ports and a display.
See all power banks in the shop. Combine it with a cable and a case and you pay for two of the three: the cheapest one is free, online and in our stores.
And if your phone is empty before lunch, a power bank only treats the symptom. First have your iPhone battery replaced, usually done within 30 minutes and with a 12-month warranty, or check all repairs for your Samsung.
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How many times can I charge my phone with a 10,000 mAh power bank?
Count on one and a half to two full charges for an average phone. The packaging states the capacity of the cells; because of conversion loss, 60 to 70 percent of that ends up in your phone. If your phone has a large battery, like a Pro Max, you’ll get just over one charge.
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Can I take a 20,000 mAh power bank on a plane?
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How long does a power bank last?
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Can a power bank charge my laptop?
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Why does my power bank charge my phone slowly?
About ThePhoneLab
For more than ten years, ThePhoneLab has been repairing phones, tablets and laptops, every day, throughout the Netherlands. Every repair starts with an honest diagnosis, no cure no pay, and then you choose what suits you: original parts or a more affordable alternative from our own brand, for every budget. Because repairing is almost always smarter than replacing, for your wallet and for the planet. No wonder customers give us a 9.5, in tens of thousands of reviews.
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