Power banks
11 products
Buying a power bank starts with one question: how many times do you want to be able to charge your phone without a wall outlet? At Strex, you can compare compact 12,000 mAh power banks for daily use with XL 27,000 mAh models for travel and festivals — including a version with wireless Qi charging, so you can leave the cable at home.
How much mAh do you really need?
The calculation is simpler than salespeople make it seem. An average smartphone battery is 4,000 to 5,000 mAh, but about 30 to 35% of the energy is lost to heat and voltage conversion during the transfer — that is physics, not a bad power bank. So, calculate with about two-thirds of the stated capacity:
| Capacity | Phone charging (±) | For whom |
|---|---|---|
| 12,000 mAh | 2 times | Daily use, in a bag or coat pocket |
| 27,000 mAh | 4-5 times | Weekend trips, festivals, multiple devices |
Still in doubt? Consider what the power bank will have to deal with most often: just a phone, or also earbuds, a smartwatch, and your travel companion's phone. If you are using more than one device per day, 27,000 mAh is the more stress-free choice.
Can a power bank go on the plane?
Yes — provided it is in your carry-on luggage, never in checked baggage. Aviation regulations allow power banks up to 100 Wh without separate permission; 27,000 mAh comes to about 97 Wh, so it remains within the limit. Practically, this means: all Strex power banks can be taken into the cabin. Place them separately in the bin at the security check; it saves questions.
What should you look for when choosing?
- ✔ Capacity — 12,000 mAh for daily use, 27,000 mAh for travel (see table)
- ✔ Number of ports — charging two devices at once avoids the "who's first?" question
- ✔ Wireless Qi charging — place your phone on it and you're done; ideal if you forget cables
- ✔ Weight — more mAh is heavier; you won't notice a 12,000 mAh, but you will feel a 27,000 mAh in your coat pocket
- ✔ Warranty — 2 years standard at Strex
Wireless charging: convenience with one condition
A Qi power bank charges any phone that supports wireless charging — just place it on top, no cable needed. What almost no one tells you: wireless charging does not work or is slow through thick cases with card holders or metal plates for magnetic mounts. If placing it on the charger doesn't work immediately? Remove the case before concluding that the power bank is broken. For the fastest charging of the power bank itself, use a good USB charger — and while on the road in the car, a phone mount keeps your charging phone in sight. You can find more mobile power solutions under electronics & gadgets.
Frequently Asked Questions
How many times will a 27,000 mAh power bank charge my phone?
On average, 4 to 5 times for a full charge, depending on the battery size of your phone. Due to conversion loss, you lose about a third of the capacity — this is normal for any power bank. For a tablet, count on 1.5 to 2 full charges.
Can a power bank go on the plane?
Yes, in your carry-on luggage — never in your checked suitcase. Up to 100 Wh (approximately 27,000 mAh) requires no permission from the airline. All Strex power banks fall within that limit and can therefore be brought on board as standard.
How long does it take to charge the power bank itself?
That depends on the capacity and the charger used: a larger power bank contains more energy and therefore needs more time. A practical tip: plug in a large power bank to charge at night, so capacity is never the problem — forgetting to plug it in is.
Can I charge my phone and earbuds at the same time?
Yes, power banks with multiple ports charge two devices simultaneously. The available power is distributed, so charging per device is slightly slower than solo — handy to know if you're in a hurry: charge the device you need first, first.
Check out the Strex power banks — from compact to 27,000 mAh with Qi — and choose the capacity that fits your day.
Want to know more? Read our article "Which power bank do I need?".