Review, Teardown: Lanu Power LP-401B 4400mAh Power Bank

Here comes another power bank thanks to an anonymous donor. This particular power bank is a Lanu Power LP-401B 4400mAh power bank, packaged in the same package with the words “Quality Assurance” as the LP-406B reviewed earlier. As a result, it confirms the suspicion that the outer package is “generic”.


The power bank itself was black in colour and roughly a rectangular brick. The top of the power bank has a push button at the centre of the ring which activates the power level LEDs and turns on the power bank. Long-pressing on it activates the 5mm LED torch, and toggles between on, SOS and off.


DSC_7402The product is shipped inclusive of a user manual leaflet and a basic charge-only USB micro-B cable.

The rear of the power bank lists its specifications, which lists its capacity as 4400mAh and the input and output both of 1A capacity. This is suitable for most smartphones, but is sub-optimal for heavy loads such as tablets.





The top of the power bank has its single USB A output, a single USB micro-B input and a 5mm white LED for a relatively weak emergency torch.


The power bank is constructed by clipping two halves together. Prying at the seam with a flat-head screwdriver allowed for the halves to come apart.


Internally, the two 18650 cells were shrink wrapped together into a battery pack, which is nice and neat and what you would expect from a quality pack. However, there are no markings on the exterior of the pack, and my nose detected something suspicious about this – was it hiding something?

The construction of this power-bank is similar to others in using two interconnected PCBs stacked one on top of the other. Visible is the top of the top PCB which has the surface mount blue LEDs arranged in a circular pattern to match the top. The top PCB is marked LP-601B V1.2-A and LP-401B V1.2-A, which suggests that the PCB is common between two models of power bank. LP likely stands for Lanu Power, which is a branding belonging to Shenzhen BlueTimes Technology.


The underside of the top PCB suggests the PCB is made in Week 33 of 2012. Just like most other power banks, there is a microcontroller with the markings ground off. The white LED is mounted on this side, as is the connections to the battery. The soldering is positively average, with it being just quickly tacked on, with a splash of solder to the right. It’s a concerning design where the current from the battery has to travel through the connectors and a fair amount of PCB to get to the inductor, as the added resistance reduces efficiency.


The bottom PCB has an open bi-filar wound inductor, which is not the most efficient sort. There is an SS34 3A Schottky rectifier diode, and a small tantalum capacitor. No bulk electrolytic capacitor is used to smooth the power output. There is also an IC marked 5056, which is likely a USB charger IC. It seems this bottom PCB is specific to the LP-401B model.


The underside of the bottom PCB has the very familiar 8205A MOSFET, a few resistors to set the USB charger detection for Apple products, and a few test points to monitor input and output voltages.


The battery pack was double-sided foam taped to the rear of the casing and took some effort to remove. Both ends of the pack was insulated with dark green cardboard.

DSC_7521 DSC_7520

The heatshrink had to be cut to get into the pack and evaluate the cells.


Looks like genuine Samsung ICR18650 2600mAh cells right? Look again …

These cells are almost certainly fake Samsung cells. It’s hard to tell, but the first thing to notice is how the lines are not matched monospace – the G doesn’t align directly under the 5, which looks a little bit off. The lot code underneath may have three or four letters from my experience. The text should look like this:


If you don’t believe me, just look at these other images of genuine cells from other power banks. It’s also the case for my genuine Samsung cells extracted from an old HP laptop battery.



The other characteristic of genuine Samsung cells is the horizontal batch code printing on the metal can itself. You can see it on the cell with the heatshrink removed – but in all my genuine examples, you can actually see at least one set of prints underneath the heatshrink. None are visible in the cells used in this power bank.

If this isn’t enough for you, lets remove the end caps and take a peek there …


I don’t know about you, but the consistency of the heatshrinking seems quite poor. The two cells even have different cap colours! I’ve always known Samsung cells to have white caps only. The blue cap one doesn’t seem right … why would they pair up two dissimilar cells? If they aren’t well matched, the safety and lifetime of the pack may be compromised.

Look a little more carefully – the spot welds seem pretty averagely done, and the cells themselves have slightly dirty tops. It’s more apparent when looking at the other end of the cells.


Looking at the underside, it is obvious that there are spot weld tacks left behind. As a result, it is very likely that these cells have been dismantled and removed from existing packs – they might not be new cells at all.

I have heard through the grapevine that there are operations out there which salvage old cells from recycled laptop batteries, remark them and rebuild packs from them. I thought that was ridiculous when I first heard it, but now that the evidence is placed in front of me, it seems quite likely that this is the case somehow.

Lithium-ion cells generally degrade as soon as they are manufactured. Cells which have reached their cycle limit tend to see about 80% of their remaining capacity left, but then they go downhill rapidly and unpredictably from there. I really can’t recommend such cells to end users under any circumstances.

If these are genuine Samsung 2600mAh cells, I’ve never seen any quite this rough and different. The power bank capacity should be 5200mAh, rather than the claimed 4400mAh. I suppose the guys actually know something about this … that’s why it’s not claiming 5200mAh, but then they might just print any number you want.

Performance Test

The performance of this power bank was tested on the new rig, following the same methodology as used in previous power bank tests. The capacity results are as follows:

Load (mA) Run Capacity (mAh)
500 1 3556.703446
500 2 3714.871695
500 3 3673.765736
500 4 3660.550617
500 5 3560.382371
Mean 3633.254773
Range 158.1682496
StDev 71.09503461
Load (mA) Run Capacity (mAh)
1000 1 3355.642847
1000 2 3083.331958
1000 3 3398.524624
1000 4 2902.136176
1000 5 3451.494462
Mean 3238.226013
Range 549.3582864
StDev 235.5389223

At the 500mA rate, the effective capacity was 3633mAh. At 1A, the effective capacity dropped to 3238mAh. It seems the consistency of the charge termination was fairly poor, in more than two runs, the capacity differed quite significantly from other runs. This could have something to do with the cells, or with the performance of the charger IC at different temperatures.

The efficiency of the converter, assuming a 4400mAh capacity, is 83% and 74% at 500mA and 1A respectively, which is acceptably good. But if we use the 5200mAh total capacity as the cell shrink wrap tries to pretend, the efficiency is a lousy 70% and 62% respectively. This is another confirmatory piece of information we can use to conclude that the Samsung cells are likely to be fake.


The voltage profile is on the high side at 500mA, but kept good regulation, which is preferable for overcoming resistance in USB cables. At 1A, the converter seems to have no concept of regulation at all, with the voltage falling below the 4.75v minimum USB voltage requirement before half-way through the discharge. It seems that the output current capacity is a lie as well, and the converter is overloaded. The PCB does shut down correctly once the batteries are depleted, however.



The ripple voltage at 500mA loading averages 471mV, which is high – the voltage should sit between 4.75v to 5.25v. With an output of 5.2v already, adding about 0.2v positive spike exceeds this limit, and is thus non-compliant with USB power output requirements. The oscillation frequency is a high 1.052Mhz, which allows for smaller capacitors and inductors to be used, at the expense of losses in switching and inductor core/winding.


Increasing the load to 1A increases the ripple to 753.6mV average, which is too high, and again non-compliant with the USB standard.


This power bank is the first power bank where it seems counterfeit cells were used in the construction. The cells themselves seem to have been used before, and may have a questionable lifetime. They are unlikely to have come from Samsung. The conversion circuitry wasn’t particularly special, with regulation difficulties at 1A, and a high level of ripple (but not the worst) which makes it non-compliant to USB specifications and potentially risky for devices.

About lui_gough

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One Response to Review, Teardown: Lanu Power LP-401B 4400mAh Power Bank

  1. hartwinder singh says:

    GREAT teardown…with all sort of probable much of details…

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