Dangerously high temp USB battery bank charger!!!

[edy]

Hi folks,
I bought one of those USB battery banks to top up my cellphone when it runs out of juice. It is called "Xtreme" 2600 mAh Portable USB Battery Bank.

http://www.xtremecables.net/2600mAhPowerStickBatteryCharger-1-1.aspx

 I have attached a photo. When I am using it to charge my BlackBerry Z10, the end with the USB connectors gets up to 74 to 78 Celsius and runs this hot during most of the charge drain!!! See the attached photo where I put a thermocouple into the end of the USB port.

Is this normal? What is going on? I usually just leave my phone in my pocket while it is charging up but I'm afraid to fry my gonads with this thing!!!!

[KSP]

FUUUUUU.....

No... Just no... I would throw it a mile personally. Batteries+heat=bad times

Anything that is too hot to touch (which 78c certainly is) should not be a portable/pocket device. I would call it faulty. I've never heard of the company but if they are a reputable brand then get hold of them and ask them wtf is going on

[rob77]

i assume there is a linear regulator inside - and that's the reason why it gets hot.
take it apart if possible to verify that, but DO NOT damage the LiPo battery inside - if you puncture the LiPo it will catch fire (in most cases) - and the lipo fire is not the one which can be easily distinguished (water is making it even worse).

you can eventually replace the linear regulator with a small switch mode regulator (you can buy ready-to-go small SMPS modules  on ebay or DX  - very cheap)

[Legit-Design]

Phone wants around 5V? LiPo/Li-ion are typically ~4.2V max? Probably not linear regulator inside. Throw it in the bin and get a working one.

[rob77]

Phone wants around 5V? LiPo/Li-ion are typically ~4.2V max? Probably not linear regulator inside. Throw it in the bin and get a working one.

i would bet on a 2 cell Lipo with a linear regulator inside

[Psi]

78C externally = Internally a contender for the smallest pizza oven

[Legit-Design]

Phone wants around 5V? LiPo/Li-ion are typically ~4.2V max? Probably not linear regulator inside. Throw it in the bin and get a working one.

i would bet on a 2 cell Lipo with a linear regulator inside

I would bet on single 18650 cell inside.

[edy]

I feel like making a USB-ended heat sink... one of those block finned aluminum ones you see on top of processor chips, and soldering a USB to it (just the outer ground)  so they are thermally connected and plugging it into the battery bank when using it. At least it will draw heat off the unit.

Just thinking it may be also that the particular phone I am charging draws a lot of current as well, whereas other phones may limit this. I know that when I used the Xtreme 1800 mAh with my phone it wouldn't charge at all and I returned it for this 2600 mAh version. The icon which indicates charging on the phone would light for maybe 5 seconds and then stop, or would say source not good enough to charge.

Alternatively I can send it to Dave for a complete teardown and arse-kicking of the company for a piss-poor design and engineering. I wonder if it is even passing safety codes or if these things are being sold around the world by some underground network of distributors, or simply governments have no resources or interest in bothering with this stuff as it is lowest priority for them (like Dave's Apple charger teardown).

[Legit-Design]

Or just return the crap and never touch them again. If enough people return that crap maybe they will stop selling them. Crap is not worth touching. If you really want you will get one good cell out of it for some other projects. Ebay is full of working cheap battery banks with usb which you can add your own cells into.

[amyk]

Does the rest of the unit i.e. the cell get hot? I think it's just bad contact creating a high resistance. Try plugging in-and-out an unconnected plug a few times. If the device charges at e.g. 2A, even a 0.1 ohm resistance means 400mW dissipated in the contacts.

[edy]

I can't tell if the cell gets hot... the entire thing is in a plastic housing. Only the metal ends I can touch (the micro USB) gets hot. I assume it is a component on the board attached on the end and NOT the batteries themselves.

I will also have to test if this happens when charging a blue tooth earpiece, and iPhone. Perhaps blue tooth draws less power so it won't heat asmuch?

[ConKbot]

I'd look into contact resistance also.  I have a battery bank (easy ACC 12000mAh,  tore one down, great build quality)  And when I'm charging it with a 2A charger, the input usb gets warm (not that hot though, just warm)  What is the output current for your battery pack?  0.5A 1A? 2A?

[mcinque]

That's what I'm asking to myself why the hell I must go thru CE (or FCC) certification, studying EMC, ESD and related literature when who should supervise cares nothing about this sh*t products...

[rob77]

Phone wants around 5V? LiPo/Li-ion are typically ~4.2V max? Probably not linear regulator inside. Throw it in the bin and get a working one.

i would bet on a 2 cell Lipo with a linear regulator inside

I would bet on single 18650 cell inside.

but then it have to have a step-up converter to make the 5V for the USB plug output. single 18650 cell is 3.7V - most of the devices wouldn't even start charging when connected to 3.7V.

[edy]

I found some YouTube videos describing perhaps a similar charger. Mine looks a bit different case-wise, but the approximate shape is the same and the 2 USB ports at the end are the same (a standard USB and a micro USB). So I wonder if the inside also uses an 18650 Li-Ion rechargeable cell and a small IC that handles the rest, like here:

PDF File of IC:

http://escooter.org.ua/_fr/1/DW01A-DS-10_EN.pdf


YouTube Videos:



? ??: Portable Mobile Power Bank USB 18650 Battery




Here is my PowerBank:
==================

[edy]

I paid $20 for this thing from a local shop. Perhaps I should open it up and take a video, I don't mind destroying it. It may be worth the educational value... how NOT to design something or perhaps a call to enforce better control and safety. It seems you can get them for $3-5 shipped directly from Hong Kong via eBay all around the world, shipping included. All the retailers are stocking up their shelves by importers buying cases of these and nobody seems to be watching.

I just found this link, unrelated company but perhaps a sign of more to come:

http://news.asiaone.com/news/digital1/recall-power-banks-raises-concerns

[ConKbot]

Phone wants around 5V? LiPo/Li-ion are typically ~4.2V max? Probably not linear regulator inside. Throw it in the bin and get a working one.

i would bet on a 2 cell Lipo with a linear regulator inside

I would bet on single 18650 cell inside.

but then it have to have a step-up converter to make the 5V for the USB plug output. single 18650 cell is 3.7V - most of the devices wouldn't even start charging when connected to 3.7V.

And it charges from a 5v usb, which means you would have to have a boost converter for the 8.4v to charge a 2s lithium battery, so youre going to need one either way

[rob77]

Phone wants around 5V? LiPo/Li-ion are typically ~4.2V max? Probably not linear regulator inside. Throw it in the bin and get a working one.

i would bet on a 2 cell Lipo with a linear regulator inside

I would bet on single 18650 cell inside.

but then it have to have a step-up converter to make the 5V for the USB plug output. single 18650 cell is 3.7V - most of the devices wouldn't even start charging when connected to 3.7V.

And it charges from a 5v usb, which means you would have to have a boost converter for the 8.4v to charge a 2s lithium battery, so youre going to need one either way

that's correct, in one of the directions you need a boost converter, no doubts.
the device in discussion produces excessive heat during powering some device through it's output. boost converters are not supposed to produce too much heat, therefore the assumption that there 2cells with a linear regulator (that would explain the excessive heat).

in case of the cell producing the heat - the whole device would be warm/hot, but only the USB end is getting hot so apparently the electronics is producing the heat. probably it's an incredibly crappy boost converter with a single cell

[sunnyhighway]

I can't believe nobody mentioned a piss poor soldering job on the USB connector as a probable cause.

[edy]

I tore open my power pack and have attached photos. I will write more about the components... please chime in on what is happening here. The 4R7 coil inductor is blazing hot. I will check the temperature of each device and see if I can figure out which is hottest.

[edy]

On one side I guess we have:

SS24 - Schottky Barrier Rectifier
B628 - CMOS voltage detector
2DLF -?
4R7 - inductor coil
And lots of resistors and 2 capacitors

On the other side we have:

DW01 - one cell LIPO battery protection IC
8205A -?
A couple resistors and a couple capacitors and a couple LEDs (under the USB)

[XOIIO]

Wait, is it just me or do those middle pins on the connector look like they are not even soldered? Sheesh.

[edy]

They wouldn't be soldered as they are data pins. The USB is only used for power in this case.

Also I can't figure out what battery is being used... cannot find those numbers anywhere. Any ideas?

[klr5205]

Even if they were no-connects I'd still expect them to be soldered... they just wouldn't be connected to any traces. I'm with XOIIO - Sheesh.

[edy]

Notice the PCB coating is still there under those pins so any reflow work would have nothing to solder to. There is no bare copper even available under those pins!

I am also guessing the inductor is getting the hottest based on when I touch it, but maybe it is just because it has the most thermal mass.

I don't know the voltage of the battery but the circuit would I assume step up the voltage to 5V from whatever the battery is (3.7v for Lipo?). I need to get out my CRO and probe around for fun!