Review, Teardown: Xiaomi (Mi) NDY-02-AL 16000mAh Power Bank

Xiaomi, or Mi for short, is a Chinese mobile phone manufacturer that have been known for delivering affordable, high quality products, with an aim to become the next “household brand”. Their product lines have diversified away from only phones and tablets to now include accessories and household appliances. To date, I have tested a few of their products, including power banks, a fitness tracker and a Bluetooth speaker and so far, they have produced very commendable results.

Many readers, looking for larger power banks, have suggested that I try the Xiaomi NDY-02-AL 16000mAh power bank. Unfortunately, as a hobbyist running a personal website, I really had no need for power banks above a certain number of units and nobody was willing to donate a unit for testing. Luckily for you all, Gearbest have stepped up to the plate, and were willing to provide me the Xiaomi NDY-02-AL 16000mAh unit for testing and review.

This review has been a long time in the making, requiring over one and a half months of testing time, and producing over 120Mb of data which needed to be processed to create the performance test results. Will it carry on the Xiaomi heritage of being a quality product offering excellent value for money? I finally have an answer. Read on.


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The unit arrived in a matte finish thin cardboard box, with a grey print Mi-logo on the front and website on the rear. Stocking labels seem to have been placed on the front, indicating relatively fresh stock dated 3rd April 2015.

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On one side of the box, there is a basic list of specifications for the product.The unit claims to have 16000mAh capacity at a nominal voltage of 3.75V for LG cells, or 3.6V for other cells. It accepts a 5V 2A charging input, and can put out two outputs at 5.1V at up to 2.1A with a maximum combined output of 3.6A.

On the other side, there are barcodes and the Mi authenticity verification label. The scratch-off panel on the authenticity verification label was removed and the resulting numbers were entered into the authenticity checker which proved that the unit was authentic.


Inside, the unit sits on a moulded cardboard tray, along with a short flat cable, and a Chinese only instruction manual. The front of the power bank is emblazoned with the Mi logo. The power bank weighed 346 grams on my cheap set of scales.


20150526-1041-6090The rear of the power bank is emblazoned with the website For protection, the ports of the power bank are taped over.


The power bank ports are beige, and the Mi logo can be seen in the plastic moulding on the top port. The two USB ports are configured to be in an opposing direction.


The other end of the power bank has all of the specs and details.


The supplied flat cable has a black tongue on the USB A port side, with no moulding marks or logos on the USB A port side. The micro B port side has a black tongue as well, with a lightning bolt logo on the moulding on one side.

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The assembly of this Xiaomi power bank is very similar to the 10,400mAh models previously reviewed. Removing the self-adhered plastic surrounds on the front panel allows access to screws which secure the body of the unit to the aluminium outer shell.


We can see the use of white diffusing tape over the LED holes, as with previous Xiaomi power banks. Removing the four Philips screws allows you to pry out the center unit using a flat-head screwdriver in the little plastic gap in the top left.


The unit consists of five LGABE11865 3200mAh cells. The construction is of high quality, with liberal use of kapton tape for insulation, quality tabbing between cells with clean spot welds, and foam tape to ensure a snug fit. Carrying on from the previous power bank, this unit maintains its thermistor monitoring of the pack temperature as well, for safety.


The main PCB is marked PB160_MB_44 dated 28th September 2014. The PCB uses a BQ24195 2.5A/4.5A single cell charger with 5.1V 1.3A/2.1A synchronous boost operation by Texas Instruments on the top side, with large MLCC capacitors sited close to the inductor for good ripple performance. It also appears that an 8A fuse is present on the top end, fusing a pair of parallel cells at the negative.


The PCB and connectors are supported by a plastic frame, which can be unclipped to reveal the underside of the PCB.


The underside seems to reveal a stack of paralleled MOSFET switches to disconnect the cells, likely to ensure sufficient capacity under high current loading and less waste heat. A second inductor and un-identified surface mount power converter is seen on the underside, which results in this unit having a unique design where the two USB ports are being provided by two separate independent converters. The whole unit is controlled by an ABOV semiconductor MC97F1204S microcontroller.

What appears to be an 8A fuse is also seen on the underside of the PCB which connects to the negative of three parallel cells. This is then bussed together with the fuse controlling two parallel cells on the other side of the PCB.

This is another unique arrangement that I haven’t seen before, and it overcomes a normal restriction by manufacturers on paralleling Li-Ion cells. Normally, most manufacturers will not warrant or recommend the connection of more than three 18650 cells together, as a cell failure will lead to significant energy dissipation with the two other cells dumping into the failed cell. Xiaomi’s answer to this is to segment the system into two strings – one having two cells in parallel, the other having three, each protected by their own fuse. In case of a cell failure, a fuse from the non-failing string will blow limiting the fault current to just the ones in parallel (at most, two other cells), thus maintaining the safety recommendations by the manufacturer. A smart solution indeed – especially in a market where some batteries unashamedly try to parallel eight cells together with no safeguards at all!


It is nice to see that the tradition of using potted inductors continues, although a shielded unit might offer even better efficiency. This reduces potential for acoustic problems.

In all, the construction resembles a high quality laptop battery pack with notable attention to safety and performance aspects.

Performance Testing

Performance testing was performed using the same configuration that has been used for most of the power bank tests, based on the “new” test rig. As this unit has a particular design, the testing was performed twice – with results for Rail A (USB port on the Mi-logo side) reported separately to the results for Rail B (USB port on the website-printing side) as they are based around two separate switching converters internally. This resulted in 30 cycles being put onto the power bank, and over a month and a half of continuous testing.

Due to the large number of data points, plotting was performed using Matlab instead of Excel, as it kept choking on the data which had over 112,000 points for a single test run at 500mA.

Charging the power bank from a 2A power adapter took approximately 14 hours, but sometimes longer if the power bank did not detect or use the full capacity of the charger. High quality cables and a high speed charger are recommended to avoid lengthy recharge times.

The Xiaomi power bank uses cells with a nominal voltage of 3.75v. Readers should remember that the number of mAh that a power bank has is not a measure of energy without knowing the voltage – i.e. 1000mAh at 3.75v is MORE than 1000mAh at 3.6v. Because of this discrepancy, this creates a reporting difficulty as all the previous tests were reported using a nominal voltage of 3.7v. As a result, the tabulated capacities are calculated on a 3.7v nominal voltage basis so as to be comparable with previous testing, with the 3.75v converted figures used to calculate efficiency and provided in text.

Capacity Results – Rail A

Load (mA) Run Capacity (mAh)
500 1 14985.00754
500 2 15024.70384
500 3 15049.38664
500 4 15016.23597
500 5 15048.71639
Mean 15024.81008
Range 64.37909971
StDev 26.61431793
Load (mA) Run Capacity (mAh)
1000 1 14937.72118
1000 2 14925.51122
1000 3 14935.82193
1000 4 14910.87274
1000 5 14908.48101
Mean 14923.68162
Range 29.24017513
StDev 13.62873608
Load (mA) Run Capacity (mAh)
2000 1 14172.33356
2000 2 14174.50544
2000 3 14181.66646
2000 4 14150.04491
2000 5 14194.86333
Mean 14174.68274
Range 44.81842551
StDev 16.34473579

The performance of Rail A’s converter is excellent, with an average of 14,824mAh at ~500mA, 14,725mAh at ~1A and 13,986mAh at ~2A loadings (all adjusted for 3.75v nominal voltage). This results in a calculated efficiency of 92.7%, 92.0% and 87.4% respectively. The discharge termination worked well, and produced very consistent figures with all ranges below 65mAh.

The underside of the unit claims the usable output to be 10,800mAh at 5.1V at a 1A loading as a typical figure with efficiency above 90%. Through my calculations, it was determined that the Rail A performance came out to 10,827mAh at 5.1V at 1A, and the efficiency assuming 16000mAh of cells of 92%, easily exceeding these claims. They also claim a 93% maximum efficiency, and the measured result of 92.7% is close enough especially considering the error contribution of the test rig.

Capacity Results – Rail B

Load (mA) Run Capacity (mAh)
500 1 15035.92678
500 2 15042.44103
500 3 14966.34885
500 4 14925.32297
500 5 14995.61476
Mean 14993.13088
Range 117.1180628
StDev 48.94981954
Load (mA) Run Capacity (mAh)
1000 1 14786.92867
1000 2 14705.82713
1000 3 14729.73557
1000 4 14745.66332
1000 5 14770.70907
Mean 14747.77275
Range 81.10154121
StDev 32.20436935
Load (mA) Run Capacity (mAh)
2000 1 13929.78144
2000 2 13817.70572
2000 3 13914.23675
2000 4 13835.42145
2000 5 13960.96812
Mean 13891.6227
Range 143.2623974
StDev 62.04549047

The performance of Rail B’s converter appears to be measurably slightly less efficient than Rail A, although not significantly so. The capacity is 14,793mAh at ~500mA, 14,551mAh at ~1A and 13706mAh at ~2A, all adjusted for 3.75v nominal voltage. This results in a calculated efficiency of 92.5%, 90.9% and 85.7% respectively, which is lower than that of Rail A. Discharge termination seems slightly less consistent with loading on Rail B, with the range of measured capacity up to 144mAh.

The underside of the unit claims the usable output to be 10,800mAh at 5.1V at a 1A loading as a typical figure with efficiency above 90%. Through my calculations, it was determined that the Rail B performance came out to 10,699mAh at 5.1V at 1A, and the efficiency assuming 16000mAh of cells of 91%, which falls slightly below the claim on usable capacity but well within the margin of error. As a result, Xiaomi should be praised for providing a figure of actual usable energy and actually meeting their claims.

Voltage Results – Rail A


It is important to remember that these voltages were measured inclusive of voltage drop in a short segment (20cm) of USB 3.0 lead and the connectors, which means that some of the voltage drop under loading is due to resistive losses in the rig.

On the whole, the output voltages showed some signs of regulation “fuzziness”, but the voltages were very well regulated on the whole. Even under the ~2A loading, the voltage did not fall below 4.85v, which is ample margin from the 4.75v USB minimum voltage requirement.

Voltage Results – Rail B


Rail B showed slightly lower voltages compared to Rail A, with more stringent regulation resulting in mostly nice straight lines with one exception at the 2A loading where it was somewhat more “frantic”. It is important to keep the scale in mind, as the jagged variances being recorded here wouldn’t really even show on a cheap 3.5 digit multimeter.

On the whole, while the voltages are slightly lower, they still don’t violate the 4.75v USB minimum voltage requirement, and are perfectly adequate.

Ripple Results – Rail A


At 500mA, the ripple was 53.48mV peak to peak, which is just above the ATX 50mV “standard”, but still quite significantly below the 150mV value that most stock chargers put out. The rate of oscillation was 343kHz.


At 1A, the ripple measured an average of 22mV peak to peak, which is a record low for my testing. Not believing my eyes, I zoomed in …


… and close up at a small time base, the average was 18.34mV peak to peak with a frequency of 475khz. An exemplary result.


At 2A loading, the ripple averaged 55.57mV peak-to-peak, again slightly more than the ATX 50mV standard but much less than the 150mV from standard OEM phone chargers. The frequency of oscillation is 946.5khz. This is a excellent result overall on Rail A.

Ripple Results – Rail B


The ripple characteristics of Rail B are completely different from Rail A. For the most part, there is negligible to no ripple on the output, except for bursts of noise which occur periodically. At 500mA load, these bursts came at a 25.2Hz repetition frequency and resulted in an average peak to peak reading of 92.15mV, mainly due to the bursts. The ripple voltage would be better than Rail A if the bursts were not present, but even with the bursts, the maximum ripple is below 150mV that stock chargers can put out and is safe for usage.


The characteristics continue with 1A loading, with 91.72mV peak to peak average ripple, and 25.2Hz repetition rate.


At 2A loading, the ripple averages 91.15mV with 25.2Hz repetition rate. As a result, Rail B has a higher average ripple due to the spikes, with mostly quite low-ripple voltage in-between bursts. The ripple characteristics are largely independent of loading.


Xiaomi have delivered once again, by producing a product that performs well, looks good and is available at a very competitive price. The unit shares similarities with the previous Xiaomi power banks by employing LG cells and TI power converters.

Quality components have been used throughout, and the performance very closely meets the stated figures. Ripple figures are quite commendable as well. The capacity of the power bank is very adequate for even power-users, and its design seems to be intelligent with a safety focus as well, which makes this unit hard to fault.

Interestingly, the two-rail design means that the performance of the two ports are slightly different, with different ripple signatures and slightly different efficiencies. On the whole, the differences are small and won’t worry most users, but it also means that it’s a bad idea to connect the output of the two ports together using a Y-cable.

Of course, it is important to note that such large capacity power banks can really stretch your patience, as the large capacity requires a long time to recharge (approximately 14 hours, subject to the capacity of your charger and the quality of your connection cable).

Those looking to purchase Xiaomi products should be aware of fake counterfeit products which don’t achieve the same quality or performance despite commanding similar prices. Look for the authenticity check scratch-off sticker and check the code to make sure you’re receiving a genuine product.

Gearbest are definitely worth considering, as they’re currently selling this unit on special, for AU$34.13 which I can vouch as being genuine based on the item I have received.

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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23 Responses to Review, Teardown: Xiaomi (Mi) NDY-02-AL 16000mAh Power Bank

  1. breech says:

    Thanks for the write up. I grabbed one of these and am very happy with it.

  2. A very helpful and thorough analysis. After going through your stuff….I feel PROUD to get hold of one. Thank you very much

  3. zicronzick says:

    Hi, I really like to read all your post and your effort to do extra work to know how the technology work behind of how that thing works….

    Now power bank industries already expanded and few major name already go to power bank businesses. If you can repeated the test like this on others branded power bank like samsung, asus and others, it would be great….

    anyway nice blog and very much info…

  4. Bob Hudson says:

    I have just purchased one of these. I also have av Aapowers 50000mAh which really is somewhere between 5000mAh and 10000mAh. I have 6 x 2600 Sony rechargeable 18650 from an Asus laptop charger which I plan to put in the Allpowers.

    Could I use the Allpowers to charge the Xiaomi or could it damage the Xiaomi.

    I have charged my Samsung phone and tablets a couple of times with no apparent damage. However after reading your teardowns I am vocerned about ripple damage when charging.

    • lui_gough says:

      In theory, you can use any source capable of providing 5v/2A to charge the Xiaomi power bank, although the standard disclaimers apply. If the output is not to spec, then damage can always occur, but since you are charging a power bank, it’s much less likely than directly providing power to a smart device.

      Normally ripple voltage can manifest strange responses from audio hum out of the headphone jack during charging, touch screen malfunctions (false touches, lack of response, shaky response) during charging, weaker radio signal indications (due to interference) through to inconsistent/incomplete charging or damage in the case of prolonged exposure. It’s hard to tell without actually measuring it with a decent oscilloscope, but again, devices are designed to expect power meeting a specification – go outside the specifications and the ramifications will vary from device to device.

      – Gough

  5. Andrei says:

    I bought this battery. Quality and capacity very good, I like that it has an aluminum housing. I put it first in loaded and noticed that 3 LEDs lit and fourth flashing from battery comes a strange sound, a sound like water flowing through the radiator. The sound gradually decreased in intensity until it disappeared. The charger is Asus, output is 5.1V with 1.3Ah. It is normal to hear sounds during charging? As a matter of capacity I’m satisfied. I loaded fonepad 7 asus tablet that has ~ 4000 mA battery. Charging the battery from 15% at 10:50 AM. From then until 5:30 PM tablet was used almost non stop light screen at maximum and wifi on. At 5:30 o’clock, tablet battery was at 84% which makes me think the tablet is limited to a small load current. If I don’t use the tablet while charging, load it in about 3 hours and a half. At 6 o’ clock the battery tablet was fully charged. At 11 o’clock PM I disconnected the battery and I noticed after the indicator lights as were 2 of 4 LEDs on. I waiting answer about noise battery during charging. I read here something about the noise but do not quite understand. Thank you! Sorry for my English and by the way, I like your review!

    • lui_gough says:

      The noise that I referred to is electrical noise rather than acoustical noise. That being said, please check that your unit is genuine by examining the packaging, the cable and the plugs first.

      As chargers and power banks use switching converters, audible noise being generated is not unusual, and can sometimes be described a squeaking, squealing, buzzing, humming, screetching,or even hissing. One common cause is a charger that is overloaded or not well made – do check by charging the unit with another charger that it isn’t the charger causing the noise issue. The construction of the Xiaomi power bank uses a potted inductor which should be relatively resistant to causing audible noise, although it might be possible under some circumstances and isn’t particularly worrysome if the unit is genuine and functions correctly.

      Tablets are generally quite high capacity batteries and take longer to charge. The Fonepad 7 has a 15Wh battery, so you can expect the 16000mAh power bank to charge it about 3 times completely from flat. Charge times of 2-3 hours when unused is relatively expected, even with normal charger as the charging process slows down towards the end to prevent battery overcharging and is a standard Li-Ion/Li-Poly charging behaviour. As for charging while the unit is being used, it is expected that charging might be slower or completely stopped as certain uses (e.g. high screen brightness, intensive apps) will cause the phone to consume almost all the incoming power, leaving little-to-none for the battery to charge. This is, again, normal and you can expect a similar behaviour with the supplied charger as well. Of course, if you have a phone with fast charging, these functions are not supported by most third party power banks at this time.

      – Gough

  6. Andrei says:

    Yes, is genuine, I already checked. I will try another charger.
    Thanks for the reply!
    Have a nice day!

  7. Bob Hudson says:

    Can you recommend a good 3.7 to 5 volt step up thst I could use in a homemade Power Bank. My plan us to use 6 x 2600mAh rechargeable batteries from an Asus Laptop (good Sonys) . I plan to use a TP4056 lithium battery chargibg.discharging protection module as the battery charger.

  8. praneeth says:

    can use 5v/1amp charger to charge this powr bank

    • lui_gough says:

      It is best to use a 2A charger as the opportunistic charging algorithm will try to take as high of a current as possible. That being said, when chargers are overloaded, the voltage normally dips, and the power bank takes this as a signal to limit the current – so it’s likely to work okay, although your charger will possibly be more stressed than normal because of this.

      – Gough

  9. praneeth says:

    should i buy mi 16000mha powr bank i dont hav 2a charger i dont have 2a charger i have xiaomi 5v/1a charger or should i connect to my laptop is safe for charging it

    • lui_gough says:

      Again, my advice in the previous reply holds. The unit will try to draw more than the rating of the charger. Of the charger is properly designed, the output voltage should fall to signal that there is a current limit. The power bank respects this if your charger is properly designed. Charging from most computers is worse as most ports are only designed for 0.5A.

      For all I know, your chargers or power banks may not be genuine … and may behave differently. The best option is to use it with a 2A or greater charger as it will shorten charge times as well (or be prepared to wait 9+ hours).

      – Gough

  10. praneeth says:

    thanks for your reply gough

  11. Hey Gough,

    A very nice and detailed review. I’m planning to buy one of these. Do you think there are any other power banks out there that have similar capacity/price with such good build?

  12. Nick Brown says:

    Wow! First of all, really great review!
    Thank you for that!
    I was wondering though, in the review you state “Performance testing was performed using the same configuration that has been used for most of the power bank tests, based on the “new” test rig.” Could you please link to the method which you used? I am assuming you have mentioned it on your site prior.
    Thank you!

    • lui_gough says:

      The “new” test rig (resistance based) is pictured here:

      Measurements were made using a Keithley Model 2110 5.5 digit multimeter in dual-measure mode, 10PLC integration time (~0.012% basic accuracy DC-Volts, ~0.2% basic accuracy DC-Amps). Unit under test and meter in air-conditioned room at 23 degrees C to maintain accuracy specifications. Samples taken at approximately 2Hz frequency. Recorded measurements exported as CSV, and integrated to determine Watt-seconds, Watt-hours and converted back to 3.7v-equivalent mAh (unless otherwise stated) for comparison.

      – Gough

  13. Joe Bernard says:

    Hi ! thanks a lot for the very well done and informative review.
    I have a question about noise. I am looking for a 5VDC power solution with very low noise.
    The device draws about 500 mA. In your experience which is the psu solution that allows for the lowest ripple ? I see for the Xiaomi power bank, that I own, that ” at 500mA, the ripple was 53.48mV peak to peak”. Is there any power adapter or power bank with much lower ripple ?
    Thanks a lot indeed again. Kind regards, Joe.

    • lui_gough says:

      It depends on what you define as “very low”, and it depends whether you need for it to be portable or not, and also it depends on how efficient you want it to be. On the whole, the Xiaomi did very well compared to others – the lowest would probably be the old Powertraveller Powermonkey Discovery ( which is only capable of 500mA but achieved a ripple voltage of 50.02mV peak to peak ( Even Anker power banks which are highly acclaimed were seeing closer to 200-300mV of ripple. On the whole, if you were talking about switching converter based power banks, I’d have to say the Xiaomi is “low ripple”.

      However, of course, you can have even less ripple. Direct supply from batteries, for example, has practically zero ripple, but might not come at the voltage you would like. Linear regulators can “waste away” that excess voltage as heat, and leave you with a practically zero ripple supply (e.g. having 6 x Ni-MH cells for a nominal 7.2V + an LM7805 regulator throwing about 1.1W away as heat). That being said, this is highly inefficient and I wouldn’t recommend it.

      Why you would need “low noise” below that, I have no idea. Most devices are designed to be tolerant of ripple and have internal capacitances to further smooth any ripples before consuming the power – otherwise, you would expect the power noise to manifest itself as stripes on a camera, hum in an audio device, etc. The other way of tackling the problem is building your own “filter” with inductors and capacitors to further smooth the output from other power banks if your end device cannot handle the already small ripple. I mean, that value I quoted in the review is about 1/3rd of that of some branded phone chargers already …

      – Gough

      • Joe Bernard says:

        Hi Mr. Gough,
        thank you very much indeed for the very kind and extremely valuable advice.
        I am very uneducated in electronics, but I think I see your point. A well designed device should have a good rejection of the noise coming from the power supply. So there should be no need for ultra low noise psu.
        Just one question about batteries followed by regulators.
        As you say, as I need 5VDC a regulator is needed.
        But are you saying that if I build a power supply with ” 6 x Ni-MH cells for a nominal 7.2V + an LM7805 regulator ” the noise will be minimal ? will the LM7805 add any noise to the one coming from the batteries I mean ?
        Thanks a lot again for the very helpful advice.
        Kind regards, Joe.

        • lui_gough says:

          Because you were asking about low-noise, that is a reason I suggested linear regulators. While they are inefficient, they are extremely low noise. While some very sensitive applications might need even less noise, an LM7805 generally has noise roughly 50uV of noise. That’s 1,000 times less than the straight output of a power bank. It’s almost impossible to read using normal oscilloscopes.

          Of course, because the regulator itself has a feedback mechanism, it does generate noise. But because it’s not using inductors to store and dump the charge in discontinuous cycles like the highly efficient switching converters do, the noise is much much less. Straight connections to batteries gives you the least amount of noise, if your application can handle the voltage variations on a battery.

          If you really need such low levels of noise or even less, you probably should be speaking to someone who designs power supplies for a living.

          – Gough

          • Joe Bernard says:

            Hi ! thanks a lot again.
            No more doubts. I will try the linear solution then for sure. The 5VDC are needed to power some usb audio interfaces I am testing. I can check the resulting noise floor of the interfaces using a SW called Arta that looks quite sensitive.
            In this way I can see the actual noise floor of the device powered by the 5VDC psu, that is what matters in the end.
            Of course the 1st I will try this evening will be this nice Xiaomi power bank.
            Thanks a lot again for the very valuable advice.
            Kind regards, Joe.

  14. anggik says:

    thanks for the review.. finally i bought this powerbank!

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