You can now get a popular power bank from Alza for just 359 CZK. All you need is this

A compact pocket power bank is one of those things you only appreciate when your phone battery runs out outdoors. The AlzaPower Onyx Gen2 10000mAh costs 399 CZK, or 359 CZK with AlzaPlus+, and offers three ports for that price. Users have also taken a liking to it, with over 5,000 units already sold and a rating of 4.7/5 based on 173 reviews.

Quick summary:
✅ Makes sense if you want an inexpensive pocket power bank for everyday use and travel, with three ports and charging for phones, headphones, and watches.
⚠️ Consider that the power bank itself charges slower (approx. 5.5 hours for the black version) and that the realistically usable capacity is lower than the 10,000 mAh stated on the label due to voltage conversion.
💡 At 399 CZK (359 CZK with AlzaPlus+), it’s one of the cheapest ways to have a backup power source from a trusted brand at hand.

Why this power bank is interesting

This AlzaPower power bank is aimed at people who want one universal backup power source for their pocket or backpack and are not looking for the most expensive premium model. With dimensions of 98 × 63 × 25 mm, it fits into a jacket pocket, and reviewers repeatedly praise its pocket size and low weight. Thanks to an output of up to 22.5 W and support for a range of fast charging standards (PD 3.0, QC 3.0, AFC, and others), it charges phones noticeably faster than older inexpensive power banks and can also handle tablets or wireless headphones.

Key parameters in plain language: how much you can actually charge

One thing about power banks that’s fair to say out loud: 10,000 mAh on the label is not 10,000 mAh that you’ll get into your phone. The capacity is stated at a cell voltage of 3.7 V (here 37 Wh), but the output runs at 5 V, and voltage conversion results in losses. Realistically, you can expect approximately 6,000 to 6,500 mAh usable at the output, which for a typical phone means about 1.5 full charges; for a smaller phone, you’ll get closer to two. This is not a flaw of this particular model; every power bank behaves this way, but it’s good to know in advance.

Good news for travelers: the 37 Wh capacity is well below the airline limit of 100 Wh, so you can take it in your carry-on luggage without any issues. Additionally, the package includes a reversible USB-C cable (30 cm), and the power bank features a Low Power Mode for safe charging of headphones and smartwatches, i.e., low-current devices that other power banks sometimes disconnect after a few seconds.

Practical aspects: ports, performance, charging

The connector setup is generous for an inexpensive power bank: 2× USB-C and 1× USB-A, so you can charge up to three devices simultaneously, and Smart IC technology automatically distributes power. However, two things are good to keep in mind. The advertised 22.5 W runs on the USB-A port, while the USB-C ports handle PD max. 20 W. And most importantly: when all three outputs are connected, the total shared power drops to max. 15 W, meaning three devices will charge slower simultaneously than a single one.

A weaker point is the charging time of the power bank itself, which the manufacturer states as 5.5 hours for the black 10,000mAh version, and some users criticize this in reviews. There are also occasional mentions that it heats up slightly under load, which is not unusual for compact power banks. The charging status is indicated by four LED indicators, not a percentage display, so you only have an approximate overview. For peace of mind, AlzaPower adds a 3-year warranty and 6-fold safety protection against overvoltage, overload, short circuit, overheating, overcharging, and under-discharge.

What users say

Ratings are a strong point here. The power bank has a rating of 4.7 out of 5 from 173 reviews on Alza (this number is shared for both 10,000 and 20,000 mAh variants and both colors), 93% of customers recommend it, and the return rate is very low, only 0.36% out of more than 5,000 units sold. People most often praise its compact size, fast phone charging, and price/performance ratio. It is repeatedly mentioned that it is truly pocket-sized and lightweight and that, unlike some competitors, it does not disconnect during charging.

Criticism mainly targets the slower charging of the power bank itself and, for the larger 20,000mAh version, its higher weight. A few reviewers encountered a defective unit (the power bank did not respond after unboxing), which Alza, according to their experience, resolved with an immediate replacement at a branch. One user also mentions that sensitive devices with very low power consumption (such as an aroma diffuser) sometimes disconnect even with Low Power Mode enabled. These are isolated comments, but it’s fair to mention them.

What is AlzaPlus+ and is it worth it for this?

The price of 359 CZK is the member price for the AlzaPlus+ program, not a regular discount. Membership costs 299 CZK annually (roughly 25 CZK per month) and primarily offers free delivery on anything without a minimum order value. But let’s be honest: for this power bank, the member saving is only 40 CZK, so the membership won’t pay for itself for a single item. It only makes sense if you regularly buy small items on Alza and primarily save on shipping costs. The program can be canceled anytime for free. If you don’t have a membership and don’t want to bother, the power bank is a good buy even at the basic price of 399 CZK.

When it doesn’t make sense

If you need to charge demanding devices or a laptop, opt for a model with higher power and capacity, such as the 27,000mAh version with 100 W. Similarly, if you want wireless MagSafe charging or a percentage battery status display, this Onyx Gen2 won’t offer it. And if you mind the longer charging time of the power bank, expect about 5.5 hours for the 10,000mAh version to fully charge. However, for a typical phone recharge on the go, the power and capacity are just right.

Verdict: who it’s worth it for

The AlzaPower Onyx Gen2 is an honest pocket power bank for a reasonable price. For 399 CZK (359 CZK with AlzaPlus+), you get three ports, fast charging up to 22.5 W, a mode for watches and headphones, and a 3-year warranty, all with a rating of 4.7 out of 5 and a very low return rate. The main compromises are predictable: slower charging of the power bank itself and real capacity lower than the number on the label, which applies to the entire category. As an inexpensive and reliable backup power source for everyday use and travel, it’s a sensible choice.

Do you carry a power bank with you every day, or only take it on longer trips?