Review, Teardown: Apotop Wi-Copy (DW21) 5200mAh Power Bank

Towards the end of 2014, I entered a competition held by Scorptec for a chance to win an Apotop Wi-Copy power bank. Guess what? I won! Thanks Scorptec!

As a bit of a hobbyist photographer, backing up photos and keeping devices charged while on packed itineraries overseas are two big challenges, and with the limits in luggage allowances, anything which saves space and weight is often welcome.

With my trip to Hong Kong and China coming up, it seemed to be an ideal device to test on my trip. Unfortunately, it arrived at my house a few days after I had left (not their fault), and had to wait till I got back. As you would probably already know, anything that claims to be a power bank often will grab my attention and be thoroughly reviewed. This time will be no different – the device will be subjected to the “full Gough test”.

The Device

The Apotop Wi-Copy (DW21) is a bit of a nifty device. This device essentially rolls together, in a small self-contained self-powered package:

  • a small embedded Linux OS running on an embedded CPU offering
  • a router with Ethernet/Wireless/USB-Modem WAN
  • a 2.4Ghz 150Mbit/s wireless-N access point
  • a web, FTP, uPnP, SMB and DLNA server
  • SDXC card reader
  • USB port for external storage
  • a power bank

With it, you can use it to create a Wi-Fi access point from a cabled connection, or extend a Wi-Fi connection by “repeating”, serve a USB modem as a Wi-Fi connection, transfer pictures and videos from a USB stick/hard drive/SD card to your phone/tablet for sharing or back-up, or vice-versa, or between USB stick/hard drive/SD card, or charge a phone/tablet. Control can be taken with just a phone/tablet without the need for a PC or laptop.

Currently retailing at AU$119 at Scorptec, it seems to be quite a unique product with many uses especially for the frequent traveller.


DSC_3399 DSC_3402

The product comes in a mostly-white colour-print cardboard box with most of the features pictured on the box. This unit was a “demo” unit sent out as a prize, hence the Demo marking on the rear.

The unit interestingly claims up to 14 hours of operation, and support for 2.5″ hard drives (meaning that the USB port provides sufficient juice to allow them to be powered, not that a drive would be accommodated inside the unit).

DSC_3400 DSC_3401 DSC_3403

The sides of the box feature QR codes as shortcuts to access their Wi-Copy applications for Android and iOS, as well as their Youtube channel for further help. The bottom of the box contains the relevant regulatory markings to indicate compliance.

DSC_3405 DSC_3408

Inside the box, you find the unit which is finished in a matte soft touch black plastic. The shape of the shell is vaguely similar to that of a generic 4 x 18650 power banks. On the top, four LEDs are provided which indicate charging (red), card/USB activity (green), Wi-Fi activity (blue) and power status (red, orange, green). The underside provides the specifications. Of note is that while the unit says it can provide a 2A output, it is only capable of pulling 1A from a charger – as a result, it may not continuously operate if your USB port load is high as the cell might drain itself to flat. A quick check with a charger doctor confirms that the unit does not draw any more than 1A despite being connected to a 2A charger. The unit is Made in Taiwan.


The front of the unit has a full size SD card slot, which appears to be compatible with SDXC cards. Underneath this is a USB 2.0 port (upside down), used for charging or for data transfer. A fairly stiff slide switch is provided to switch the unit between off, power-bank only operation, and Wi-Copy (i.e. access point, file copy) modes. The stiffness of the switch prevents inadvertent powering of the device, but might need a little bit of fingernail strength to switch it.


DSC_3409The opposite side of the device features a reset button, used to return the device to factory defaults in case of trouble. It also provides a microUSB B connector for power input and charging. Plugging this into a charger allows the unit to operate for longer (or indefinitely, should the USB load be low enough). Finally, a plastic RJ45 Ethernet jack is provided for the WAN connection.

The unit itself weighs in at a fairly low 170 grams. This is not much heavier than most smartphones, and is much less than most tablets.



Also provided in the bundle is a charging cable, with AWG26 conductors (fairly average). A double-sided quick start leaflet is also provided, one in English and one in Chinese. An Australian and New Zealand Warranty Card is also provided to meet local consumer regulations.


The fun in getting a new toy is to try and figure out how it works, and what its made of. As a result, I decided to tear it down almost immediately. The unit itself is constructed without screws, and comes apart with some careful prying at the seams.


Removing the top cover, reveals the Wi-Fi antenna double-sided taped to the top lid. This comes off easily and “hangs” to the side. Over half the internal volume is occupied by the internal PCBs, with just two 2600mAh 18650 Lithium ion cells in parallel providing power. The pack itself is shrink wrapped and marked with AE 18650 C-26 3.7V 5200mAh 19.24Wh GL. No further attempt was made at trying to understand the origin of the cells.


The top of the top PCB is dated Week 50 of 2013, making the device a “little old”. Visible on the top PCB is a Realtek RTS5187 card reader, which is in charge of the SD card slot. There is also the magnetics for the Ethernet port, labelled HC mjlsmd1602-AC.

The power conversion is provided by a TI Benchmarq BQ24278, which is a Lithium-ion charger IC capable of up to 2.5A (but probably configured down to 1A). The USB power output is provided by a TI TPS561032 96% Efficient Synchronous Boost Converter with 4A switch. These ICs are considered fairly good quality parts, although their performance can be constrained by the design and other components.


The PCB is not screwed into the case, and is instead weakly adhered into place. Removing it exposes a large aluminium plate for a heatsink, with a thick thermal pad to draw heat away from the main SoC, a Realtek RTL8196D, commonly used in routers. In fact, the green PCB is a module, CWFB122 from Chipsip which implements a single-stream 1T1R 2.4Ghz 802.11n router on a small module. Also integrated on the module is the flash memory that contains the firmware for the whole system.

The patterning on the thermal pad suggests sub-optimal contact with the thermal pad, and this is use to the fact that the module itself has no “standoffs” from the main PCB to apply pressure against the pad. As a result, the module rests slightly tilted with regards to the heatsink, resulting in uneven pressure. The device runs warm, but did not overheat however.


Removing the module reveals a mostly plain PCB on this site, with an assortment of passives, MOSFETs and a 12Mhz crystal. Now we know almost everything about the insides of the device.

Setting it Up

When first using the device, it presents itself as an open Wi-Fi access point with a specific unique network name. Connecting to the network with automatic DHCP configuration and navigating to allows you to access the main HTTP interface which allows you both access to your files, as well as access to configuration settings.


Direct access to files through the web browser is possible, without any security requirements. By clicking on the top right icon with the cog, it is possible to access the settings dialogue.


Here, you can set numerous options. For example, the WiFi Repeater option allows you to connect to another network as a client and use it as the WAN for the router, thus acting as a wireless to wireless router. It will automatically survey for networks, which you can choose to join if you have the correct credentials.

wi-fi repeater

Otherwise, if you are using cabled connection or a USB modem, you can configure the WAN using the second button.


One of the unusual discrepancies is the MTU size, which is only allowed to take the values 1400-1492 bytes (normally for PPPoE) despite Ethernet having an MTU of 1500 bytes in general. This may mean a slightly reduced throughput rate through the router due to increased overhead where it is not necessary.

Another important point worth configuring is the Wi-Fi settings themselves.


By default, the Wi-Copy is set up to be a ‘good neighbour’ in 20Mhz mode. Unfortunately, this restricts the 802.11n to a physical link rate of 72.2Mbit/s maximum and it will not achieve the 10Mb/s even in the best condition. Only when running in 40Mhz mode with no interfering neighbours is that even remotely possible. I would suggest configuring 40Mhz mode anyway if you are using it with N-compatible devices only (i.e. no B or G), as when the “paired” channel is busy, throughput falls to regular 20Mhz mode levels as normal.

Changing the SSID to be more recognizable is also advisable, but even more-so is to turn on encryption and configure a password. This is especially critical, because the servers on the Wi-Copy are configured to not require any passwords and to be accessible to all network users. Securing the network to allow only your trusted devices to access is paramount to ensure the security of your data. Setting an admin password is also advisable.

But wait, there’s still more settings available in the Advanced Settings icon.


Windows sharing, otherwise known as SMB, can be configured through the Samba icon. By default, it is turned off, although it can be very handy for streaming to Android phones (e.g. using BSPlayer) or when working with regular PCs and laptops. DLNA sharing is also available, however, I did not test it. Time setting allows for setting the NTP servers.

Firmware Upgrade functionality is also available, and provides details of the presently running firmware, but no new firmware is available to my knowledge.


Analysis with the PC

Connectivity and Access Details

Connecting to the Wi-Copy on the desktop allows us to do some thorough analysis of what its capable of. It seems like the Wi-Copy is configured to assume the address permanently, with a DHCP server that allocates addresses starting at with about an 8 hour lease. The unit itself does come up under network discovery as an RTK_AP, with defaulted Realtek serial numbers and model numbers.

apotop configh

The configuration access pages, as well as HTTP access is provided by GoAhead Webserver, as hinted by the headers:


Unfortunately, I didn’t find a way to do a card to USB or USB to card copy through the web browser interface, which seems to be customized for mostly phone usage. But it was possible to click on a file to stream it, or download it to your computer. Clicking into a folder of images produces a pleasant “thumbnailed” image navigation screen.


Clicking on the images allows you to have a slideshow as well, which is pretty cool.


Further probing showed that the device can be accessed via anonymous FTP as well, which seems to be a little risky. Securing the wireless LAN side is highly advised for this reason.


Likewise, if you have Samba enabled, access without password is also possible too. The machine name is RLX-LINUX with default membership to WORKGROUP.


As I have the luxury of running the whole home network, I was able to run some nmap scans to discover exactly what was exposed on the WAN and the LAN side. It seems that the Apotop appears to be secure from the WAN side, without any open ports or exposed uPnP. The LAN side has the services we mentioned already, as well as uPnP. DLNA was not enabled on this scan.

Nmap scan report for
Host is up (0.0021s latency).
Not shown: 1923 closed ports, 71 open|filtered ports
21/tcp   open  ftp         vsftpd 2.3.2
| ftp-anon: Anonymous FTP login allowed (FTP code 230)
|_drwxrwxrwx    2 0        0            4096 Jan 19 21:22 sda1 [NSE: writeable]
80/tcp   open  http        GoAhead-Webs embedded httpd
|_http-methods: No Allow or Public header in OPTIONS response (status code 400)
|_http-title: HTTP File Server
139/tcp  open  netbios-ssn Samba smbd 3.X (workgroup: WORKGROUP)
445/tcp  open  netbios-ssn Samba smbd 3.X (workgroup: WORKGROUP)
137/udp  open  netbios-ns  Microsoft Windows XP netbios-ssn
1900/udp open  upnp?
| upnp-info:
|     Server: OS 1.0 UPnP/1.0 Realtek/V1.3
|     Location:
|       Webserver: OS 1.0 UPnP/1.0 Realtek/V1.3
|       Name: RTK_AP
|       Manufacturer: Realtek Semiconductor Corp.
|       Model Descr: WLAN Access Point
|       Model Name: RTL8xxx
|_      Model Version: EV-2010-09-20
MAC Address: A4:0B:ED:05:31:93 (Unknown)
Device type: general purpose
Running: Linux 2.6.X
OS CPE: cpe:/o:linux:kernel:2.6
OS details: Linux 2.6.9 - 2.6.31
Uptime guess: 0.090 days (since Mon Jan 19 19:35:27 2015)
Network Distance: 1 hop
TCP Sequence Prediction: Difficulty=206 (Good luck!)
IP ID Sequence Generation: All zeros
Service Info: Host: RLX-LINUX; OSs: Unix, Windows; CPE: cpe:/o:microsoft:windows

Host script results:
| nbstat:
|   NetBIOS name: RLX-LINUX, NetBIOS user: <unknown>, NetBIOS MAC: <unknown>
|   Names
|     RLX-LINUX<00>        Flags: <unique><active>
|     RLX-LINUX<03>        Flags: <unique><active>
|     RLX-LINUX<20>        Flags: <unique><active>
|     \x01\x02__MSBROWSE__\x02<01>  Flags: <group><active>
|     WORKGROUP<1d>        Flags: <unique><active>
|     WORKGROUP<1e>        Flags: <group><active>
|_    WORKGROUP<00>        Flags: <group><active>
| smb-security-mode:
|   Account that was used for smb scripts: guest
|   Share-level authentication (dangerous)
|   SMB Security: Challenge/response passwords supported
|_  Message signing disabled (dangerous, but default)
|_smbv2-enabled: Server doesn't support SMBv2 protocol
| smb-os-discovery:
|   OS: Unix (Samba 3.2.15)
|   NetBIOS computer name:
|   Workgroup:
|_  System time: 2015-01-20 08:43:41 UTC+0

I didn’t investigate what happens in case of LAN range collisions or with uPnP performance in the case of port forwarding.

Testing seemed to work just fine with most SDHC and SDXC cards thrown at it, and tests confirmed that the unit supports FAT, FAT32, exFAT and NTFS filesystems, which covers the bulk of what would be used. I did not do any testing for ext2/3/4.

SMB Server Performance

One of the things we would be interested is in seeing how good the server performs when copying files from a USB key or card to the computer. A basic copy initiated through Windows seemed to report a lacklustre speed of at most, 2Mb/s. The file copy seemed to run and stall at its own will, suggesting the CPU on the Apotop device might have been strained somewhat. Under heavy loading, cryptic error messages noting “index out of bounds” occured during large copy tasks. This suggests to me that the Samba implementation is probably half-baked.


Generally less issues were had when one-operation was performed at a time. My standard stress of SMB servers involves mapping a drive and running CrystalDiskMark on it. Unfortunately, like many embedded devices, this didn’t pass completely with small block accesses causing errors. However, the difference between 20Mhz and 40Mhz mode can be seen in the two screenshots below.

smb-stability unstable-under-certain-workloads

It’s not quite a doubling, and that’s due to the fact that there won’t be a “perfectly clean” pair of non-overlapping channels available (e.g. 1 and 6 are free, or 6 and 11 are both free).

A Note on Speed

Assuming the sticker-rated 10Mb/s for copy, a 128Gb card of photos will take over three and a half hours to copy between storage devices. I wasn’t able to confirm the copy rate, as copying via the PC was not supported and a rate was not displayed on the mobile application. Downloading to the PC and uploading it back to the storage card is possible, and would move at about 2Mb/s at most realistically (over Wi-Fi, non-optimal channel conditions) – the same card will take just over 18 hours to download.

Considering a USB 3.0 card reader will easily shuffle 40-100Mb/s on most modern cards, heavy shooters might probably still be better served by a laptop and USB 3.0 reader despite the weight penalties. Less avid photographers, with less demands (e.g. JPEG point and shooters taking only 1-2Gb/day) would easily be served by the Wi-Copy.

Battery Life Check

There might be some cases where running on battery would be desired, especially when out-and-about, and so it would be nice just to see how long the device can last on battery. In order to do this, I set up a “synthetic” test environment with the Apotop connected to an Energy Efficient Ethernet/Green Ethernet port on the WAN, and a USB 3.0 32Gb USB key connected to the USB port idling (~70 to 100mA draw). The Apotop was configured for 40Mhz channel and was connected to a client which sent 65500 byte ping packets once every second until the device stopped operating. The Apotop was left disconnected from any other source of power during the test.

Under these conditions, a battery life of 13 hours 36 minutes and 34 seconds was recorded. Of course, if you plug in a hard drive, it wouldn’t be able to achieve this, as the drives consume much more power. This is pretty close to the 14 hour claim on the box, so it’s not entirely unachievable depending on the scenario.

The indicator LED on the top serves as a battery gauge as well. Unfortunately, it is very coarse, only offering three levels of indication – green for full, orange for midway and red for emptying. The indicator glows red with ample time to spare, and can actually continue operating for quite a while after it begins to shine red.

Mobile Applications – Android

In order to extend the level of possibilities for the drive, Apotop offers a mobile application for many platforms, of which I only tested those for Android and iOS.

Screenshot_2015-01-28-19-59-03The application for Android appears to be written and optimized for phones, and was installed onto my Nexus 7 running Lollipop 5.0.2. The application was a small sub-2Mb download. with limited permission requirements.


Screenshot_2015-01-28-20-12-02Screenshot_2015-01-28-20-12-11Screenshot_2015-01-28-20-14-05The main window of the application lists the mounts – the USB and SD card, from which the user can navigate down the tree to select files to view or to perform actions on them. Single selection by pressing down and holding on a file or multi-selection through the use of the icon in the top left corner is possible, however it seems that the pop-up menu that appears after single selection is a bit buggy.
Screenshot_2015-01-28-20-13-20 Screenshot_2015-01-28-20-14-10Screenshot_2015-01-28-20-12-40The options provided are as above. Certain files can be previewed directly in the application, while non-supported files will require you to launch third party applications to handle them. For media, I found BSPlayer was able to handle videos with aplomb, however some applications are not compatible with the format or with the “links” provided and will refuse to open the files.The options screen allows for you to perform some actions, one of which is to check the remaining free space on the mounted storage devices. This is necessary if you want to avoid problems during a file copy … like this:Screenshot_2015-01-28-20-19-37Screenshot_2015-01-28-20-14-15 Screenshot_2015-01-28-20-14-23 Screenshot_2015-01-28-20-13-38File copies can be initiated via the multi or single file selection screens, and generally proceed in the background handled by the device itself. The status is shown in the status view itself. Copies are made into a dated folder, rather than directly to the folder chosen, and a copy log is provided as well. The application is also happy to display in landscape as well.Screenshot_2015-01-28-20-19-53

Mobile Applications – iOS

The situation is very similar on iOS, where a phone-optimized app is provided.

IMG_1082 IMG_1083

The application works fine on a tablet, of course.

IMG_1084 IMG_1085

In portrait mode, the sidebar only comes up if you tap on the Wi-Copy text in the top corner, otherwise the background photo/video viewing area occupies the whole screen.


However, counter-intuitively, when displayed in landscape, the sidebar cannot be collapsed and instead stays there on the side. To save you from my bad media taste, I’ve mosaiced the content being displayed – but you can get it to go full screen by pinching to zoom. Unfortunately, that causes the media to restart from the beginning. This can be slightly annoying.

IMG_1087 IMG_1088








Similarly to its Android counterpart, it has very similar application options. There is one key difference in terms of what will be played or supported by the Apple products, and that comes down to its codec support. Importing to the library is only supported for files which conform to Apple’s encoding requirements, otherwise you will get the following error message.

IMG_1090Power Bank Performance

Now we get to the rather onerous part of the review, where the power bank performance is tested. Using the same dummy resistive test load, and precision 5.5 digit multimeter, five test runs are made at each 500mA, 1A and 2A equivalent loadings for a total of 15 full charge-discharge cycles. The recorded voltages and currents in dual-measure mode are integrated to provide the total energy, which is then divided by nominal voltage to back-calculate the effective mAh capacity of the battery. This allows us to determine the effective efficiency of the power bank solution.

Testing was performed with the Wi-Copy in power bank only mode. Without further ado, here are the capacity results:

Load (mA) Run Capacity (mAh)
500 1 4674.01709
500 2 4664.918738
500 3 4679.177189
500 4 4661.492931
500 5 4684.331341
Mean 4672.787458
Range 22.8384102
StDev 9.553598679
Load (mA) Run Capacity (mAh)
1000 1 4325.486384
1000 2 4345.119154
1000 3 4308.914368
1000 4 4314.054463
1000 5 4306.893556
Mean 4320.093585
Range 38.22559734
StDev 15.74045753
Load (mA) Run Capacity (mAh)
2000 1 3639.732422
2000 2 3619.903614
2000 3 3623.036236
2000 4 3602.776053
2000 5 3594.502148
Mean 3615.990094
Range 45.23027342
StDev 17.78345129

From the results, we can see that the resulting capacities are 4673mAh at 500mA, 4320mAh at 1A and 3616mAh at 2A. The corresponding efficiency figures are 89.9%, 83.1% and 69.5% respectively. The efficiency figures are generally good for 500mA and 1A, although the fall at 2A suggests that the converter is not properly designed for a 2A loading.


This hypothesis is borne out by the voltage versus time graphs. At the 500mA loading, the power bank is capable of maintaining its voltage fairly stably between 4.88 to 4.91v. At 1A, it is between 4.79 and 4.84v. At 2A, however, the voltage remains below the USB standard requirement of at least 4.75v and is thus not sufficient to ensure proper charging of devices. It also exhibits sawtooth behaviour which suggests a struggle by the power conversion circuitry to maintain voltage regulation.

The coarse indicator behaviour is exhibited in power bank only mode as well, with the power bank shutting down permanently and cleanly when the battery is depleted until it is recharged.

An investigation of the ripple and noise voltages over the average voltages above was undertaken using a Picoscope 2205A as the measurement device.


At 500mA loading, the average peak-to-peak ripple measured 35.2mV which was excellent. The converter switching frequency was 620khz, which is considered medium to high.


At 1A loading, the average ripple approximately doubles to 61.38mV peak to peak. This is still below the ~150mV exhibited by “stock” phone and tablet chargers, which is safe for your devices.


At 2A loading, the average ripple almost doubles again to 115mV. This is still below 150mV, and is a commendable performance if not for the fact that the voltage itself is too low to adequately ensure fast charging of your tablet devices.


The Apotop Wi-Copy packs a lot of stuff in its small and lightweight case. It appears to be an ideal innovative travel companion, but is not without its own drawbacks and limitations.

One of the limitations is the flexibility and configurability of the router. This includes a lack of configurability as to DHCP IP range (may be needed to avoid network IP range conflicts), server/gateway IP, or provide static port forwarding. The port forwarding issue itself may be moot given the fact that this device will likely sit behind another NAT (thus NAT traversal is nearly impossible anyway), but it would be nice in the case that it doesn’t (e.g. 3G modem, or direct to a PPPoE modem).

The performance of the SMB server is not suited to heavy workloads, and the default password-less configuration of all of the servers implies a need to keep the wireless side of the network only for trusted machines. The WAN side, however, seemed to be secure.

The limited power input charge rate also means that continuous usage with a hard drive attached and wireless routing in use might be challenging. The power bank functionality itself was adequate up to 1A, with slightly diminished efficiency, although at the 2A rate, the voltage and efficiency fell too far for it to be an optimal charger for tablets. It is, however, still very much suitable for smaller load devices, for example, phones.

Despite this, there are many instances even in the vacation I just took where this device would have been very very immensely useful. For example, where you have a wireless captive portal which only allows a certain number of devices, by using the wireless-extender feature, it would NAT all of your devices to appear to be coming from the Apotop Wi-Copy itself, thus allowing you to share the one login with more devices.

The file copy was also very serviceable, despite the limited speed, which should suit most “lighter” photographers. Those who shoot many raws (hundreds of Gb of photos) might need to look elsewhere due to the limited speed. However, it does work well as a wireless card reader for a tablet, allowing for quick sharing and reviewing of photos – just another one of its many uses.

For those who might be a little bored in the hotel room, it also allows you to stream videos from hard drives, extending the storage capacity of your tablets and phones. It’s like a wireless drive where you can choose the storage medium.

Despite its usefulness, there are still potentially some situations where you will find that such a device just doesn’t work. Part of the problem is that some establishments have an “anti-rogue AP” feature turned on, that causes their access points to broadcast spoofed disassociation packets that stop your own Wi-Fi hot-spots from being connected to. The FCC in America has already moved to prohibit this, but this ruling doesn’t apply outside of the US and it still seems to be the case in some high-technology Australian venues (which I will not name). So maybe the Ethernet cable and a laptop are still a necessary evil in some places.

As a result, users will have to weigh up whether the device is worth the price to them, and whether the caveats mentioned above are of importance to them.


As a bit of a hobbyist, I enjoy putting devices through their paces and taking them apart in my spare time – whether I’ve purchased them, won them or had them donated for testing. If there’s something you’d like to donate to be reviewed, feel free to drop me a line and you might see them reviewed here.

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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