Is it worth buying a no-name powerbank on Aliexpress? Blind purchases and 50 Ah measurements

p.kaczmarek2 1485 6

TL;DR

A no-name AliExpress powerbank labeled “Power Bank” and claiming 50 Ah at 3.7 V was bought for about 50 PLN (~15 USD) to see whether the bargain is real.
The casing advertises “fast charging,” but the unit has no Quick Charge support, only 5 V/2.1 A output, and a QC trigger cannot raise the voltage.
Charging from 0 to 100% draws less than 16 Ah at 5 V, while discharge tests deliver about 12.5 Ah at 5 V.
The biggest red flag is the mismatch between 50 Ah and 74 Wh: the numbers imply roughly 20 Ah, suggesting bad labeling, a typo, or creative marketing.

Generated by the language model.

This content has been translated

View the original version here

Report a violation of the law

Reply Cool? Ranking DIY | New topic

Notify about new articles

📢 Listen (AI):

» | Topic author Helpful post? (+11)

Post #1
21874718 31 Mar 2026 14:25

I've been presenting my capacity tests of various powerbanks on the forum for a while now, but I've recently realised that I've been too conscious of choosing good models such as Baseus , JoyRoom or Romoss . For this reason, I decided to go for the first cheapest 50 Ah powerbank from China and see what happens. Will I get a package at all, or will they send a brick?
I paid about 50PLN (~15USD). The price is quite small, but maybe that's because importers don't have to make money when I buy direct from overseas?

The case says "fast charging" but not "quick charge" - there will be no QC standard, i.e. supplying higher voltage than 5 V?

Look in vain on the casing for information about the model of the powerbank. According to the sticker, the model is simply "Power Bank". The "Container" on the packaging is already some kind of a nameplate.

There is quite a long product description on the packaging, but I don't see any specifics.

A USB C cable is included.

Finally, on the powerbank itself, there is what looks like a model name - GB35590-2017. These 2017s are worrying. Declared capacity: 50 Ah at 3.7 volts,. That would make a good match. What surprises me is the 74 Wh.
After all, if you multiply, it comes out rather 185 Wh of energy? Even if they were to take losses into account, it blandly comes out many times less. Could it be that it is not 50 Ah after all, but, say, 20 Ah?
Let's check further. Production date May 2025. I am also concerned about the voltage and current - only 5 V and 2.1 A? There is not even QC.
Ports - supposedly the orange colour indicates a higher current port?

The manual says some interesting things, supposedly the input can be up to 20 volts, I would be afraid to check this.

First load tests.
The powerbank is able to provide a total current up to about 2.5 A, then the voltage drops. My phones (Xiaomi 11 and iPhone 7) are charged at 5 V, current up to 1 A. The QC Trigger is unable to trigger a higher voltage.

Next it is time to check the capacity.
Charging is done with a current of just under 2 A. Charging from 0 to 100% shows on the meter less than 16 Ah drawn (at 5 V).

After multiplication, here we have 80 Wh. You can already see that the expected 50 Ah output will be far short of this, as there are losses both when charging the cells and when discharging them. Nevertheless, let us check. Three separate tests:

At 5 volts, approximately 12.5 Ah can be obtained. This gives us 62 Wh. And the capacity?
The nominal 50 Ah is at a cell voltage of 3.7 V, so you have to recalculate. You also have to take into account the losses on the inverter; in this series I have taken a fixed conversion factor of 0.85. Output: 12.5 Ah at 5 V, nominally 20 Ah. Unfortunately ...

In summary , there are two problems here.
The first problem is the lack of QC, this significantly slows down the charging of modern devices. The packaging slogans 'fast charging', but that's just marketing text, it's different to supporting the Quick Charge standard.
The second problem is capacity. The first thing that surprises me is the declaration of 74 Wh of energy while claiming 50 Ah of capacity. How did they come up with that? As the cells inside are nominally 3.7 V, after all, from 50 Ah it will come out around 185 Wh rather than 74 Wh. To get 74 Wh at nominal 3.7 V, the capacity would have to be ~20 Ah, not 50 Ah.
You could even conclude that this is a 20 Ah powerbank that a creative marketing person changed 20 to 50 to make it look better, while forgetting about those watt-hours because he probably didn't even know what they were...
Or a typo crept in.

Cool? Ranking DIY
Helpful post? Buy me a coffee.
About Author
p.kaczmarek2 p.kaczmarek2

Moderator Smart Home
Offline

Joined: 26 Dec 2014

Posts: 14333

Help: 648

Posts rating: 12235

Points: 139826
p.kaczmarek2 wrote 14333 posts with rating 12235, helped 648 times. Been with us since 2014 year.
ADVERTISEMENT
#2 21874764 31 Mar 2026 16:01

E8600 E8600

Level 41

» | Helpful post? (0)

Post #2
21874764 31 Mar 2026 16:01

I could be wrong but I infer from the casing that it is on 18650 cells the question is how many 16? Then with 3.5 Ah cells it is possible that it would show close to 50 Ah. A bit strange with this fast landing because similar cases handle up to 12 volts.
ADVERTISEMENT
#3 21874821 31 Mar 2026 18:52

tzok tzok

VIP Meritorious for electroda.pl

» | Helpful post? (0)

Post #3
21874821 31 Mar 2026 18:52

The Chinese have an original way of counting capacity in Ah - it doesn't matter how the cells are connected, they simply multiply the capacity of one by the number of cells and state this on the case. Add to this their 'miracle' 18650 cells with a 'capacity' of 6 Ah, and there we have what we have.
ADVERTISEMENT
#4 21875246 01 Apr 2026 12:48

kotbury kotbury

Gantry automation specialist

» | Helpful post? (+8)

Post #4
21875246 01 Apr 2026 12:48

No longer just Chinese. I use 6V zinc cells for roadside warning lights and I bought one with a capacity of 7Ah (perfectly OK) and the importer also sold one with a capacity of 50 Ah. To my tentative remark that this is physically impossible (unless they are selling camouflaged nuclear fuel cells) the salesman said (sic!) that this is new technology and, after further prodding on my part, announced that he had rewritten the Chinese label. HANDS DOWN....
ADVERTISEMENT
#5 21878509 06 Apr 2026 16:18

partyzancik partyzancik

Level 25

» | Helpful post? (+2)

Post #5
21878509 06 Apr 2026 16:18

E8600 wrote:
I could be wrong but I infer from the casing that it is on 18650 cells the question is how many 16? Then with 3.5 Ah cells it is possible that it would show close to 50 Ah. A bit strange with this fast landing because similar enclosures handle up to 12 volts.

No . There are usually 9960115 flat cells inside and the difference in capacity often depends on the number of cells used and multiples of 10000mAh capacity.
https://a.allegroimg.com/original/114aff/b965...ulator-Bateria-Tablet-PowerBank-10000mAh-3-7V
From left Baseus 30Ah , 20Ah , redmi 20Ah and baseus 10Ah
#6 21878736 06 Apr 2026 22:09

Mateusz_konstruktor Mateusz_konstruktor

Level 37

» | Helpful post? (0)

Post #6
21878736 06 Apr 2026 22:09

What is the role of the USB Type C port?
In addition to charging the powerbank itself, can an example of a smartphone be charged via this port?
#7 21879594 08 Apr 2026 09:46

lukepopek lukepopek

Level 3

» | Helpful post? (0)

Post #7
21879594 08 Apr 2026 09:46

What’s the point of buying a Chinese power bank without QC and then complaining that it doesn’t support that protocol? You knew exactly what you were ordering, after all... Secondly, to me, a power bank without QC is just electronic waste, so I wouldn’t want one even if it were free – but everyone has different requirements.
Create an account, log in here. You will receive points by participating in discussions.
Join this discussion.

Install Elektroda application

Didn't find an answer? Ask Artificial Intelligence

*I agree to send the question to OpenAI, Anthropic PBC, Perplexity AI, Inc., Kagi Inc., Google LLC - owners of language models in order to prepare the best response. The companies may monitor and log information entered into the form.

*I agree to publicly display my question and answer. The question and answer will be publicly available to everyone. The process may take a few minutes. Upon completion, you will be redirected to the page with the answer.

Wait...(2min)

Reply Cool? Ranking DIY | New topic

Notify about new articles

📢 Listen (AI):

Report a violation of the law

FAQ

TL;DR: This FAQ is for buyers comparing cheap marketplace powerbanks with branded options. A unit sold as 50000 mAh delivered only about 12.5 Ah at 5 V, and the tester summed it up: "fast charging" is just marketing text when Quick Charge is missing. It helps you spot mislabeled capacity, fake charging claims, and risky blind purchases before you spend even 50 PLN. [#21874718]

Why it matters: A low sticker price can hide slower charging, lower real capacity, and labels that contradict basic watt-hour math.

Alternative	Price paid	Claimed capacity	Measured / described result	Quick Charge
No-name AliExpress powerbank	~50 PLN	50 Ah, 74 Wh	~12.5 Ah at 5 V, about 62 Wh output	No
Baseus / JoyRoom / Romoss	Not stated	Not stated	Mentioned as previously chosen "good models"	Not stated

Key insight: The 74 Wh marking is the giveaway. At 3.7 V, 50 Ah would be about 185 Wh, so this unit behaves much more like a 20 Ah product relabeled as 50 Ah. [#21874718]

Quick Facts

The tested unit cost about 50 PLN and was advertised as 50 Ah, yet its own casing also listed only 74 Wh, which conflicts with a true 50 Ah rating at 3.7 V. [#21874718]
In load testing, total output current reached about 2.5 A before voltage sagged, while the printed output rating was only 5 V, 2.1 A and no higher QC voltage could be triggered. [#21874718]
Charging from 0% to 100% drew under 16 Ah at 5 V, or roughly 80 Wh at input, already far below what a genuine 50 Ah claim suggests. [#21874718]
Three discharge tests produced about 12.5 Ah at 5 V, equal to roughly 62 Wh output; using the thread’s 0.85 conversion factor gives a nominal capacity near 20 Ah, not 50 Ah. [#21874718]
One commenter estimated the case may hold 16 cells and another noted that some sellers simply add each cell’s rated Ah together, regardless of connection method. [#21874764]

Why does a no-name Aliexpress powerbank claim 50000 mAh but show only 74 Wh on the case?

Because the numbers do not match the same battery pack. At a nominal cell voltage of 3.7 V, 50 Ah would equal about 185 Wh, not 74 Wh. The tester concluded that 74 Wh fits a pack closer to 20 Ah, so the printed 50000 mAh looks inflated or creatively relabeled. That mismatch is the clearest sign the headline capacity is not trustworthy. [#21874718]

How do you calculate the real capacity of a powerbank from discharge results like 12.5 Ah at 5 V?

Convert the USB output into watt-hours, then back to nominal cell capacity. Here, 12.5 Ah at 5 V equals about 62 Wh. The thread then applies a fixed 0.85 conversion factor for inverter losses, which gives a nominal capacity near 20 Ah at 3.7 V. That is why the measured result is far below the claimed 50 Ah. [#21874718]

What is Quick Charge and how is it different from generic "fast charging" written on a powerbank package?

Quick Charge is a specific higher-voltage charging mode, while generic "fast charging" can be only marketing text. In this test, the package used the phrase "fast charging", but the powerbank delivered only 5 V and the QC Trigger could not force a higher voltage. The tester states directly that slogans on the box are different from actual support for the Quick Charge standard. [#21874718]

What is a QC Trigger and how do you use it to check whether a powerbank supports higher voltages than 5 V?

"QC Trigger" is a test tool that requests higher USB output voltages from a powerbank, instead of leaving it at the default 5 V. In this thread, the tester connected a QC Trigger and checked whether the unit would switch above 5 V. It did not, so the test showed no working Quick Charge output despite the packaging claims. [#21874718]

How should I interpret a powerbank label that says 50 Ah at 3.7 V but only outputs 5 V at 2.1 A?

Read it as a high capacity claim paired with a low-power output stage. In this case, the casing listed 50 Ah at 3.7 V, but output was marked only 5 V, 2.1 A, with no QC. The tester also measured practical output near 12.5 Ah at 5 V and a total current limit around 2.5 A before voltage dropped. That combination points to slow charging and overstated headline capacity. [#21874718]

Why do some cheap Chinese powerbanks count capacity by adding up all 18650 cell ratings regardless of how the cells are connected?

Because that method makes the printed number look bigger, even when usable output does not. One commenter says some sellers simply multiply the capacity of one cell by the number of cells and print that total on the case, without regard to how the cells are wired. The same comment also warns about so-called 6 Ah 18650 cells, which further inflates the label. [#21874821]

What is an 18650 cell and how many of them would a true 50000 mAh powerbank typically need?

"18650 cell" is a cylindrical battery cell format that commenters infer may be inside this case; in the thread, it is discussed as the basic unit whose capacities sellers may add together. One commenter estimates that 16 cells rated at 3.5 Ah each could add up to something close to 50 Ah on paper. That number is presented as an inference from the casing, not a confirmed teardown. [#21874764]

How can I test a powerbank's real charging and discharging capacity at home with a USB meter and load tester?

Use a meter for charge input and a load for discharge output. 1. Fully charge the powerbank and record input; this unit drew under 16 Ah at 5 V from 0% to 100%. 2. Discharge it through a tester and record output; this one gave about 12.5 Ah at 5 V. 3. Convert to Wh and compare with the printed mAh and Wh labels. Repeating the discharge three times, as done here, helps confirm consistency. [#21874718]

Why would a powerbank with an orange USB port still fail to provide Quick Charge or higher output voltage?

Because port color is not proof of protocol support. The tester notes that the orange port supposedly suggests a higher-current output, yet the unit still stayed at 5 V and the QC Trigger could not negotiate any higher voltage. In practice, this sample behaved like a basic 5 V powerbank, not a real Quick Charge model. [#21874718]

What risks are involved in trying a 20 V input on a no-name powerbank manual that looks unreliable?

The main risk is damaging a device whose labeling already contradicts itself. The manual reportedly says the input can go up to 20 V, but the tester explicitly says he would be afraid to check it. When a powerbank already shows a 50 Ah / 74 Wh mismatch and lacks confirmed QC behavior, an unverified 20 V test becomes a blind gamble rather than a safe feature check. [#21874718]

Baseus vs JoyRoom vs Romoss vs a no-name Aliexpress powerbank — which offers the most honest capacity for the money?

The thread points toward the branded options as the safer bet for honest specs. The author says he had previously been too careful to choose models such as Baseus, JoyRoom, and Romoss, then deliberately bought the first cheap 50 Ah no-name unit to see what happened. That blind purchase measured closer to 20 Ah nominal and lacked QC, so the no-name option did not justify its headline claim. [#21874718]

How much real output capacity at 5 V should I expect from a genuine 20000 mAh powerbank after conversion losses?

This thread suggests about 12.5 Ah at 5 V is consistent with a nominal pack near 20 Ah after conversion losses. The author explicitly uses a fixed 0.85 factor for inverter losses when translating between 3.7 V cell capacity and 5 V USB output. So, in the thread’s own method, a real 20000 mAh class unit can land around 12.5 Ah at 5 V rather than the full nominal figure. [#21874718]

What does the marking GB35590-2017 on a powerbank usually refer to, and does it say anything about quality?

In this thread, the marking functions only as a label and not as proof of quality. The tester notes that the unit shows what looks like a model name, GB35590-2017, and says the 2017 part is worrying. He then relies on measured behavior instead: 5 V only, no QC, and effective capacity near 20 Ah. So the marking alone did not predict good performance or honest labeling here. [#21874718]

Why do modern phones like Xiaomi 11 and iPhone 7 charge slowly from some powerbanks even when the packaging says fast charging?

They charge slowly when the powerbank only offers plain 5 V output and lacks real fast-charge negotiation. In the test, both Xiaomi 11 and iPhone 7 charged at 5 V with current up to about 1 A, and the QC Trigger could not unlock a higher voltage. The author states clearly that box text saying "fast charging" is not the same as actual Quick Charge support. [#21874718]

What are the warning signs that a cheap marketplace powerbank is rebranded, mislabeled, or using creative marketing instead of real specs?

Look for contradictory labels, vague naming, and missing charging standards. This unit had a model listed simply as "Power Bank", packaging branded as "Container", a claim of 50 Ah but only 74 Wh, and no working QC despite "fast charging" text. The author’s sharpest conclusion is that it may be "a 20 Ah powerbank" relabeled as 50 Ah by creative marketing. Those signs together are stronger than any single sticker. [#21874718]