Review, Teardown: *Fake* Xiaomi (Mi) NDY-02-AD Silver 10400mAh Power Bank

It might seem that I’ve been singing the praises of Xiaomi/Mi power banks lately, and that’s because they’re very good products. However, the journey to obtain the product is often fraught with more difficulty than expected.

In my case, when I ordered my initial silver unit for my own review, it was lost in the post, delaying my progress. I decided to try and order a second batch of units from a different seller to try and speed up the process of getting one, while the first seller eventually agreed to ship me another unit.

The initially ordered unit was the one that went into the silver review, and that unit was a genuine. However, the order from the other seller turned out to be counterfeit. This is one of the big problems of trying to buy the Xiaomi – there are so many counterfeits! Alas, there are many sites which tell you how to spot one, but sellers rarely provide enough information to tell at a glance, and sometimes they will send you a product which differs from their pictures.

After a protracted several-week back and forth with the seller, which included some terms I was less than happy about, I managed to get a full refund for the products. Many people weren’t as lucky. This gave me certainty, as I could then proceed to test the products and find out if they were any good.

So in a bit of a twist from the regular, I’m going to do what few people have done before, and actually review a counterfeit product. This might come in useful for people who have purchased one, and need some support when it comes to identification and proof of counterfeit product.

The Items

It was pretty much a case of “I knew you were trouble when you walked in …” with these counterfeits. These were sold out of a trading company in Hong Kong which probably supplies many eBay sellers under different names.

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The counterfeit units came in clear plastic cases with a white paper over-wrap. This over-wrap doesn’t fit nicely, and the edges are folded, which represents poor quality. There is even a pretend serial number, with the number 472700190770 which is identical on both units and should never be.

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DSC_8232The rear of the wrap is plain and white, with no authentication sticker in site.

The unit arrives neatly packed in a clear plastic case which seems to be a nice touch, although depending on the handling, the case itself could have a few cracks in it. Visible is the cable, the unit and a manual – pretty much the same inclusions that the genuine power bank has.

But remember, the genuine version never comes in a plastic case!!!

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DSC_8238Taking the contents out, the inclusions are similar, although the finish on the power bank is different. While both are aluminium, the finish on the counterfeit is a coarser more reflective look, with imperfections at the edges (you will see later).

The unit itself weighs in at 218gm, which is a little lighter than the 252gm/260gm result from the two genuine units.

 

 

Side by Side Comparison

Things are definitely clearer for all when the units are put side by side (or top-bottom).

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The genuine unit is above, the fake unit is below. It can be seen that the fake unit has a slightly more translucent plastic, with a less-refined power button in terms of its inset and large LED indicator holes. It also has a different microUSB port, a similar looking USB port but omitting the mi logo – zoom in to see.

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The genuine bank is on the left, the fake is on the right. The coarseness of the finish can be seen when placed side by side, although physically they share identical dimensions.

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In my case, it seems the URL is printed a little higher, and it’s the older xiaomi.com URL, although genuine banks do carry this URL as well.

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The underside shows a clear difference, with the genuine above, and the counterfeit below. Note how the genuine has a smooth finish, whereas scored lines can be seen on the fake (just barely). The printing on the fake is much more contrasty, being a silver on white “label” whereas the genuine has a sharp grey paint print on a plastic cover that has no wavy texture. The letters in the Li-ion logo seem to spell Li-ien on the fake.

A look at the cables also shows the telltale fake sign – the genuine cable on the left has a black tongue and no Mi logo! The fake has a Mi logo, and a white tongue, which it shouldn’t!

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Plugging it in, you will find that the fake cable also doesn’t perform data synchronization as it has no data wires wired through, but the genuine does.

Other differences are found in LED behaviour – with them remaining on during discharge instead of very occasionally blinking (as the genuine unit does). Recharging LED indication is identical, and so is the charge time at five and a half hours.

Teardown

Taking the unit apart like a real Xiaomi isn’t going to get you anywhere. As it turns out, this unit is constructed differently. You will need to start at the tail end, by removing the label and unclipping the end cap which holds the guts in place.

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Once you’ve done that, the whole unit can be pushed out of the metal shell. The imperfections in the manufacturing can be clearly seen here.

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Unlike the genuine Xiaomi, there is rubber foam tape inside the shell after pushing the unit out.

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What is it made out of? Well it’s certainly not the Samsung or LG cells which are advertised by Xiaomi – these are unbranded cells, which are unmarked and appear to be locally produced (of questionable quality and safety). The PCB is blue and marked 9113-M4 on this side. It seems the D+ and D- are shorted together, so this unit acts as a dedicated USB charging port.

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There seems to be damage to the insulation from being “pushed into” the sharp edges of the metal shell during construction. There is also evidence of stray solder-balls. Should the insulation wear through, there is a potential safety risk in short circuiting with the metal shell should the positive somehow detach or touch the shell. As the cells are of questionable origin, they may or may not have any PTC protection internally. It wouldn’t surprise me if it didn’t …

There are no NTC thermistors to be seen either – this is part of the temperature sensing required for safety and higher speed charging and is another advertised feature of Xiaomi power banks.

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The whole rear of the unit appears to be formed with a white plastic carrier, adding to the weight (and possibly compensating for cells which are light, a sign of low capacity). The underside clearly shows the indicator LEDs on the PCB and the holes in the body of the case. This design features no diffusing tape or dark plastic, so the indicator differs from an authentic Xiaomi in having certain viewing angles that are glary (direct view of LED) and also light leakages from each LED that light up the surrounding plastic. Definitely not of the same quality there.

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The other side of the PCB shows just one unidentified controller, U1, which controls all operations. There is no Texas Instruments controller, as advertised by Xiaomi. The inductor is a regular, open, unshieleded type, with an undersized 1A SS14 Schottky diode. This is not proper design for a 2A converter. There are some ceramic capacitors on the output, but not many. The PCB is very recent, dated week 31 of 2014.

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Speaking of which, the tabbing and battery connections leave a lot to be desired. The single tab strip doesn’t look like it was applied with much care, with poorly aligned spot-welds and the pack “falling out of shape”. The wire connection is made via very thin hook-up wire – definitely not the best choice here.

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They didn’t fare much better on the top – arguably, it’s even worse, with poor quality wire soldering and solder splashing everywhere. The tab strip is too long as well, which increases the risk that the excess ends may eventually touch something they shouldn’t.

If you’ve read this far, there is absolutely no doubt that this is not an original Xiaomi product.

Performance Test

Keep in mind, this is not an authentic Xiaomi product and the results that follow are not representative of what you will get from a real Xiaomi product. They may even not be representative of the performance of your fake Xiaomi product, as there are several counterfeit designs out there.

Testing was performed using the same methodology that the other Xiaomi products were tested with. Of note is the nature of the resistive test load – when the voltage falls below the nominal voltage, the current falls as well. As a result, the load levels of 500mA, 1A and 2A (corresponding to 10 ohm, 5 ohm and 2.5 ohm) are only sustained by a true 5v source – the actual currents are actually a little less.

Lets take a look at the capacity results:

Load (mA) Run Capacity (mAh)
500 1 3857.50123
500 2 3873.520161
500 3 3828.532666
500 4 3804.587905
500 5 3787.785843
Mean 3830.385561
Range 85.73431843
StDev 35.6354511
Load (mA) Run Capacity (mAh)
1000 1 3714.424338
1000 2 3719.15866
1000 3 3706.623432
1000 4 3670.331475
1000 5 3683.2535
Mean 3698.758281
Range 48.82718495
StDev 21.04722632
Load (mA) Run Capacity (mAh)
2000 1 2960.503267
2000 2 2941.377836
2000 3 2924.84206
2000 4 2924.311745
2000 5 2902.682109
Mean 2930.743404
Range 57.8211585
StDev 21.57758676

At about 500mA, 1A and 2A loadings, the capacity was 3830mAh, 3699mAh and 2931mAh respectively. The results were very consistent, with all ranges below 86mAh. This is below the advertised 6800mAh minimum, and 10400mAh typical/nominal value. It’s no surprise – it’s a fake. Using the provided rating, the efficiency is 36.8%, 35.6% and 28.2% respectively, a far cry from the up to 93% claimed for real Xiaomi products.

As a result, it can be concluded that the batteries are significantly under capacity. It is likely the pack is 4800mAh in total, with 1200mAh per cell, with a conversion circuit that is about 80% efficient. Not the worst 18650 cells, but not good either.

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During testing, however, it showed significant problems with voltage regulation. As mentioned in the teardown, I was skeptical based on the Schottky diode rating that the unit was able to sustain 2A load, and indeed, it couldn’t.

At the “2A loading”, the voltage started at below 4.5v and continued falling to about 3.9v towards the end. Because of the low voltage, the actual current delivered was closer to 1.4A rather than 2A due to the resistive load. As a result, the unit is incapable of even meeting the specifications printed on it in terms of current load and will not be able to charge any device at 2A.

At the ~1A loading, it only just managed to stay within the 4.75v lower limit for USB voltage, until the end of discharge. At 500mA, it was very stable at 5v, rather than 5.1v as printed on the outside. Again, its performance does not meet its specifications.

A look at ripple and noise is revealing as well.

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At the 500mA loading, the ripple averages 434.6mV peak to peak, which is high (above the 150mV of normal wall chargers, and ~100mV of the genuine Xiaomi) and close to the absolute limit of 500mV peak-to-peak imposed by the 4.75v-5.25v range requirement.

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When testing at 1A, the power bank exhibited a ripple with two main frequency components. This increased the peak to peak ripple significantly to 827.8mV, which is extremely high and out of specification for USB. This is likely to cause stress and potential damage to equipment.

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While testing at 2A, it seemed it had settled back down to 834.1mV peak to peak, but then I discovered that the power bank actually does alternate between ripple regimes, especially at start-up.

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In this case, at the “2A” loading, it produced an average of 1800mV peak-to-peak, for a whopping 36% ripple content. But considering it didn’t actually give out 5v, and closer to 4.4v, the ripple content is actually closer to 41%.

This sort of performance earns it the title of worst powerbank tested to date in ripple performance.

Why?

One question I get asked a lot is – given that Xiaomi products are relatively inexpensive, why would counterfeiters try to target such an inexpensive product? The margins are already slim, so why would they bother going after such a product if what they are interested in is profit?

In short, I don’t know. It’s probably got something to do with volume. Initially Xiaomi power banks were hard to get your hands on due to shortages of stock – the manufacturer couldn’t keep up with demand, leaving a demand “gap” which counterfeiters could capitalize on. A good product with good reputation will see good demand, and even with slim margins, it may be possible to make up for it in sales volumes. Maybe they even have a few spare cells they need to get rid of.

But alas, the jig is up, and many pages have identified such counterfeit items. So why do they keep selling it? Well, they’re hoping that you don’t find out because it’s so well made. Maybe they’re hoping that by the time you find out, it’d be too late and you’re past all buyer protection scheme entitlements.

Or more likely, they want to dump the product on you. The scheme works like this – sell a given product, it might be rubbish but if the buyer complains, then offer a partial refund on the guise that a full refund is only available if you send the item back, and knowing that the cost of postage is uneconomical, many people will settle for this. Often the partial refund is small to the point of being offensive (in my case it was), but it will be enough that the seller can still make a tidy profit.

Should you settle?

Which neatly brings me down to this point – should you settle?

In a word, no. Protest. Dig in your heels. Don’t give up. If you’ve purchased something counterfeit from eBay by PayPal, you are covered by buyer protection. The policy has specific clauses in relation to counterfeit products:

Under Section 4.3 Potential Buyer Risks:

COUNTERFEIT ITEM CLAIMS

If you file a claim about a counterfeit item you may be required to:

  • Obtain documentation from a qualified third party to substantiate your claim and/or
  • Destroy the item and provide evidence of this at your expense; or
  • Make the item available for the seller to collect at their expense.

It is against the law to possess or sell a counterfeit item.

Under Section 4.4 Potential Seller Risks:

ITEMS MAY NOT BE RETURNED If your buyer files a claim about a counterfeit item they may be required to:

  • Obtain documentation from a qualified third party to substantiate their claim and/or
  • Destroy the item and provide evidence of this at their expense; or
  • Make the item available for you to collect at your expense.

The payment may be reversed.

It is against the law to sell a counterfeit item.

As a result, if the item is counterfeit, you should be able to contest this for a full refund. This is all without posting the item back unless the seller pays to collect it or have it posted. The only burden is a need to prove the item as counterfeit, and to destroy the item on their instruction and document it.

Often a clear statement in regards to you knowing your entitlements and threatening negative feedback and PayPal cases will eventually succeed in resolving the matter in your favour, although often at the cost of leaving positive feedback anyway. I suggest you take this route – you really don’t need to waste more of your time.

And afterwards, you might have a product in your hand, but I would suggest you consider disposing of it immediately. It’s a safety risk to both you and your devices (some have exploded and caught fire).

Conclusion

The fake Xiaomi power bank may look similar to the original, but it couldn’t be a more different product. The product does not feature the same level of design and safety as the genuine one, and is composed of low quality components.

The capacity falls below half the stated capacity, while simultaneously being unable to meet the current output rating and producing so much ripple and noise to be a risk and threat to your devices.

If you receive one of these, or have one in your posession, I would highly recommend you stop using it. There is nothing to be gained if it catches fire, and burns down your house. There’s nothing to be gained if the power is so unstable that it damages and kills your $500 smartphone. All for a US$20 counterfeit charger.

As it turns out, there are several different variants of counterfeit Xiaomi powerbanks, and almost certainly each of them will be slightly different in performance. But it seems likely, inferring from this unit, that they all are a long way away from ever meeting the same performance standard of the genuine Xiaomi.

About lui_gough

I’m a bit of a nut for electronics, computing, photography, radio, satellite and other technical hobbies. Click for more about me!

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14 Responses to Review, Teardown: *Fake* Xiaomi (Mi) NDY-02-AD Silver 10400mAh Power Bank

  1. George says:

    Thanks for the really interesting teardown!
    This one was almost exactly similar to mine, except mine has a red PCB, and has an unpopulated header for another diode. It is also made on the 14-7-4, and has K-810D on the PCB.

    I always wondered why it was never able to provide a high current! I now know why!

    Again, thanks 🙂

    • George says:

      You are right about the dumping as well. Sorry to spam, but I would like to add that I had the exact same ebay experience – the seller kept going forwards and back with partial refunds. They even started off with a £1 for a £15 bank! I wasn’t having it, so I stuck to my guns and got a full refund after 2 weeks of back and forth arguing with them, I eventually got a full refund.

      • lui_gough says:

        In the end, buyers have to do this otherwise the sellers will keep profiting and won’t learn that it doesn’t pay to use other people’s intellectual property (design) and trademarks (logos) to sell their sub-standard product. In the end, it’s a fairly “cheap” lesson to learn, losing out on a few “cheap” power banks and postage – because regardless who it is in the chain, it will likely mean that sellers will stop selling the product (seeing people keep complaining about it), they stop buying it from upstream suppliers (who then might stop making them because nobody buys them).

        Letting them get away with a small refund isn’t going to do this. Likewise, it’s small change if it really ends up doing any collateral damage. I’ve since destroyed my unit by taking it to bits and disposing of the parts separately after physically damaging them – it’s not worth the risk to use it.

        Information is key. So far, the majority of people buying fakes could only comment that their power banks had “around” half capacity. That’s only part of the story. It seems yours is a different fake unit – it seems there are about three variants I have spotted in photos, and possibly more. These are likely to be different stakeholders who all have something to gain from riding off the popularity of the Xiaomi products, and are (in essence) competing with each other. I wonder if the performance could be worse than this one? (I took a good look at the inductor on this fake, and it was a loosely hand-wound single-wire type which is not great either.)

        – Gough

        • George says:

          Ill email you some pictures of it. Anyway, this one is actually a really good fake. I have used it about 4 times, and it has charged my samsung galaxy S4 about 3.5 times from empty. However, I have to turn the phone off as the charge current is about 600 milliamps, and the phone actually discharges, while running down the power pack at the same time. Also, the charging port is broken, as if I insert the cable in the normal way the LEDs flash and the bank whistles, but if I lift the cable up really high and put pressure on the port then it charges. However the charging current is really terrible, and it takes about 15 hours to charge. Also the spot welding on the cells is terrible, and one actually fell out at one end when I pulled it apart to see why the current was so low.

  2. Hank Roberts says:

    recommended here where a counterfeit is being discussed (not sure if it’s a third, or fourth, or fifth variety — yet)
    http://budgetlightforum.com/node/31160#comment-691895

  3. Honorato says:

    Thank you for such an extensive review.
    No doubt mi power bank is fake and I will ask for full refund.

  4. Saqaway says:

    I have agreen one it is ok or not

    • lui_gough says:

      The Xiaomi units do come in a variety of colours, with gold and silver being the most available. You will need to check the code-label, finish, cable, logos, etc to determine whether it is really authentic or not. If it is not authentic, then it could be risky to use.

      – Gough

  5. snailmail says:

    i also got a fake one . it seems their charging circuit ic is pretty sophisticated its only the cells that are of 3rd class ..
    here is post regarding it . i have some good 4.35 volts spec cells . but it charges only to 4.2 volts . .though the ic has provision of 4.35 volts chemistry liions. also its charging at 500ma max whareas it should charge at 1.2 Amps..

    i hope some one could help me decipher the chinese data sheets

    http://www.electronicspoint.com/threads/need-help-regarding-altering-battery-bank-tp4221b.274398/

  6. Chandra mouli says:

    Mine has no logo on the cable but still its fake

  7. Benjamin E. says:

    Gough, I’m curious as to what temperature the boost converter runs at, especially if it is under-spec’ed.
    Do you have any way of testing that?

    I ask this, because most semiconductor failures happen as a short-circuit. This could cause a fire.

    I know it happened with a generic “lipstick” size power bank a coworker of mine had bought.
    The boost converter somehow failed and shorted out, eventually melting a PCB trace. The diode was fried and split in half, which makes me think there was either an output overload, short circuit, MLCC filter capacitor failure, or actual failure of the diode itself.
    The control IC was physically burnt as well, so it was completely unrecognizable. It was only an 8 pin SOIC, which handled the boost converter and the cell charging. (Being a “lipstick” type, it only had one cell. I didn’t get to test the cell to see if it suffered any damage)

    -Ben

    • lui_gough says:

      Sadly, I don’t have the unit any longer and I don’t have a reliable way to test it without spending a lot of money (i.e. IR thermal imaging). On the whole, even IR thermal imaging is highly dependent on material emissivity being known to provide accurate readings, and laser spot thermometers generally don’t have a small enough spot to provide good resolution on PCBs.

      The temperature would highly depend on load, and with proper designs with current feedback, should shut down the converter on overload. Should this fail, then dangerous situations could arise. Other than that, if the microcontroller should lock-up with the MOSFET powered up, that could be a simple route to smoke as it would basically short the cell over with an inductor, diode and MOSFET. It could be static damage causing MOSFET to go leaky as well in addition to the failure modes you have identified.

      Small PCBs may also mean that the true culprit is hard to identify as it could have been a stray piece of solder melted away by the short, or collateral heat damage to several components confusing the analysis process.

      – Gough

  8. Rohith says:

    I bought mi power bank but it is written mi+ on it but it has all features of original once like nothing on cable and all

  9. Ken Taylor says:

    You ask “why would counterfeiters try to target such an inexpensive product? ” then answer “In short, I don’t know. It’s probably got something to do with volume.”

    The cells represent the major portion of the power bank’s cost so the profit comes from the low cost of providing inferior and therefore much cheaper cells. In the extreme they can even be recycled from laptops etc as can be seen in the teardown of these “new” Ultrafire cells http://lygte-info.dk/info/batteryDisassemblyUltraFire%20UK.html

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