Another of these solar powered USB power banks.. well, solar rechargable
but also rechargable from a standard USB power supply
And this particular one, I bought it from a UK seller called.. "etang_uk" etang.
I'm guessing its a Chinese seller and it, the £5 price seemed quite cheap
for a 5000 milliAmphour bank, and I didn't expect it to be 5000 milliAmphour
I tested its capacity. It came in a 2.4 Amphours. So 2400 milliAmphour for for a 5 Amp hour power bank
No great surprise to be honest
This one is different though. It doesn't even look like the picture on its listing
Whereas the other one had four LED positions and the solar energy.. the ..
the.. little LED that lights with the output from the solar panel was just sharing one of those positions
This one has its own indicator position for the green LED that's connected to the Solar panel
And its got four positions for the other usual charge indicators.. the state of charge
Another slightly disappointing feature about this one is that compared to the last one I took apart
Which had quote large sections of the silicon solar cell
This one has much noticeably smaller sections. Its no great deal, particularly in the UK
you know.. we don't get much sunshine anyway. But its just a wee bit of a cheap thing
However.. I've already had this open and I'll open it again to show you guys whats inside
and the circuit does include protection for the charging from the solar panel
so although its not going to stop it being baked in the sunshine, it does have the facility that
once the lithium cell is fully charged, if you leave it in a window sill
for a long period of time its not going to over charge it because it has the DW01 circuit and the MOSFETs
and the negative from the solar panel is on the correct side of that
Its not connected directly to the solar panel.. er to the lithium cell
So, let's pop this open.
Nice enough cases. I quite like the cases.. they're smart
Not waterproof at all, but, I'm not even sure I'd say they were splash proof
This one I think this one's got slightly different
catch system. Its also.. I might change the LEDs since like this I might change the LED for a warm white LED.
Just because I prefer the warm white LEDs..
Oh.. thats quite a tight clip
and its just closed again.. that's quite annoying
oh yes, its one of these things that the clips just repeatedly snap closed because there are so many of them
Righty ho..
and once again the rubber bumper is trapped just in the casing
So there's the.. the cell in here, I've marked the weight of it. Its 70 grams
and this one, unusually it's in sort of black foil. I'm not sure why this one's in black foil
What immediately came to mind was protection against heat, but thats quite the opposite
the black would actually absorb more heat from the sunlight.
and this one is stuck in with a bit of double sided tape
and its not that hard to get out.
its just a bit of foam tape on the back
and then tacked onto fairly generous pads on the back of this
urmm... so the solar panel, lets put that circuit board out in fact
I might need a smaller screwdriver bit for that
Is that going to fit?
mmmYeah that'll do..
It has three screw positions, but just two screws
Changing the LEDs should be fairly straight forward. It is a through hole, but its soldered on the other side
So, popping that off reveals the MOSFET package
Its got another position. Its go the position for the two parallel MOSFET packages
which gives extra current protection
You know.. it can handle the higher current, but in this case they've just one
which is cheaping out a bit
Oh.. this has got a number on it
The chip has a number on it.. thats good
T power T P 4 3 5 1 B
So thats T Power T P 4 3 5 1 B
Thats interesting
Most.. usually those chips are anonymous
So theres one boost converter for both the sockets
I'm guessing, you know they claim two 2 Amp sockets. I"m guessing its probably
I'm not 100 % sure what its going to be able to handle in terms of current
Lets do a little experiment shall we?
Lets get
errrrrr...
This!
and plug it in
and plug in a test load
So the voltage has dropped to 4.4 volts
at 830 milli amps. Lets stick it to two amps
Its now 1.48 Amps
and the voltage has dropped to about 4.13
So its not really capable of 2 Amps
Its struggling even at 1 Amp so
typically like most of these things kind of 500 milliAmps is all its really going to comfortable with
What more is there to say about this?
It has that protection thats got the, on the other side
its got the DW01 chip which is the common protection one for the cell
So that'll be protecting against over discharge and over charge
Oh I have actually managed to change the shape of this cell slightly by squishing it
but thats ok, I'm fine with that. Whats the worst that could happen? Its just a bit fat Lithium cell
So 2.4 Amp hour.. 70 grams
I'm pretty sure the one in the other solar, the other unit, was also around 70 grams
You know, I can just check that right now and tell you.. one second..
Yeah.. the other one had similar capacity and it was 68 grams
So yup, 70 grams typically seems to equate in these instances to
err.. the capacity of about 2.4 Amp hour.
The little solar panel, I quite like these solar panels. I like the fact they've got a matt finish on them
Its quite smart.. and they just clip out and they're quite nicely designed
Yeah.. its strippable for components.
Nice fat lithium cells
Or just keep it as the power bank.
But, quite neat. You know its not bad
Its functional, its not quite what they state it is
But having said that, for the money I think thats perfectly acceptable. So, not bad at all.
I've downloaded the data sheet and also made a very slight hack to this whilst I was putting it back together again
I changed the LED from the cold white to a warm white LED. Just because I prefer that colour.
I know some of you think "whats the difference.. cold white.. warm white"
I think it softer on the eyes and I just like it
Another interesting thing to note about that little LED is that the pin that controls it in the chip
errr its drives LED, it doesn't use the 5 volt boosted supply to drive it, which is good
It runs directly from the positive connection of the lithium cell
and you can add your own choice of resistor to limit the current through the LED
Which isn't going to be a huge voltage difference between the LED and the cell
so it could be quite, in this case, this suggests a 30 Ohm resistor
But that is capable of syncing up to about 100 milliamps so you could theoretically
you know, make one of these power banks with a fairly decent light in it.
The whole thing could be basically a flash light with the facility to actually charge stuff
The chip came from a Chinese server.. the data sheets.. and it took a long time to download
I just thought I'd mention that if you want to look up TP4351B online
and look for the PDF data sheet. Then it will take a while to download if you get it from the same place I got it
because its definitely one of those you can see it just creeping down and its just seven pages
but go and have a cup of tea whilst its doing it. Its that thing, you know, the stuff coming from the Chinese
web sites just seems to be bottle necked in some way
Theres an oddity in the data sheet in that it almost alludes to being used..err, designed to handle
maybe in two different forms a 4.2 volt or 4.35 volt lithium cell
I'm not sure about that. Its got two sections for VBat.
And.. I'm guessing 4.35 is that in your style of cell thats got a more stable chemistry at the higher voltages?
I know that an ordinary lithium cell thats designed to charge to 4.2 volts max would not really be overly thrilled at 4.35 volts
It would probably take the charge. It would, you know..."work".
It wouldn't necessarily explode in flames at that point.
but it would have been charged up to a much greater capacity, but you would get very
significant shortage, you know, it would shorten the life span of the cell
It would damage it over time very quickly.
On the lower end of the scale, the, it says "VBat" and 2.85 volts.
Thats presumably the point at its going to cut off
I wonder if it cuts off the LED flashlight at the same time
or if it just cuts off the boost converter, I don't know about that
It possible has that thing whereby if you plug something like an LED directly into the USB output
Even though its switched off the boost converter with out actually knowing whats in this chip, if it had any way to control it
I don't know if theres any chance that it would actually just trickle current through that 2.2 microHenry choke to that output
So, umm, I don't know if it can be discharged accidently below that voltage
However, it also states another voltage which is 3 volts and I'm not sure if thats just the point that it will kick in again
It'll re-enable it once its charged back above 3 volts
The quiescent current of the chip is about 15-25 microAmps
Which is ok, but when you consider with the solar panel, thats not really that critical
Although obviously this isn't really designed with that in mind
but, certainly in the case of this one, even just ambient lighting is going to boost, you know
give a few milAmps during the day that you know thats going to more than compensate for losses through quiescent leakage
The quiescent current is the current the chip will draw off from the cell
just when its not doing anything. Just when its in standby mode
I will say, when I put the white LED in, as a precaution I disconnected the lithium cell
and just out of interest, before reconnecting it again I held it up to the light and pressed the button
just to see if it would kickstart the circuitry, and it did, and it lit the warm white LED
through the chip, and it actually stayed lit for quite a distance away from these LED floodlights so that was quite interesting
Errrm.. other than that, what other features are worthy of note?
Not an awful lot. There is one oddity here..
the input and the output, the VDD in from the charge port obviously goes through the current regulating circuitry
before it goes out to the battery.
The two sockets here, the USB IN and the USB OUT, the
I'm not sure whats in this chip. It would be nice to see a schematic, just a diagram of whats inside the chip
But its got this random resistor here.. R3NC .. thats all it says
I'm not sure what that is, but it connects between the USB OUT and the...
Oh. you know that might be a sense resistor..
That might be a current sense resistor..
... I'm not sure ..
to detect when the sockets.. the actual circuit being overloaded
possibly..? I don't really know .. umm
but other than that, you know, fundamentally its an interesting chip
Of the seven pages of the data sheet, only two are really, you know, useful
The rest is technical specifications and the sort of physical dimensions specifications and you know
example circuit board layouts. This one carries most of the data that you need
and this one has the sort of schematic layout. It is a very minimalist approach
I'll be looking at other power banks in future and just like noting to see
I'll keep this data sheet handy. I want to see if the pinout is roughly the same
If it the identical chip thats unmarked, or if its clones or whatever
Theres other things that are not 100% sure
91%, 3.7 volts, I'm not 100% sure what the .. umm..
what some of these things are
because they're in Chinese and its kind of
"Yeah, I kind of want to know" but how..
Someone mentioned you can use your phone with the translation app to actually just look at the Chinese characters
That.. maybe thats, I"m not sure if thats globally the same thing
but here in the UK, err. that doesn't work unfortunately. It doesn't seem to handle at this point in time the Chinese characters
But, yup, its an interesting chip. Its certainly.. and this pack
its not up to, it doesn't meet its specifications, but other than that, you know
its quite robust, its quite nice. Its a chunky little pack.
Its seems to have a modest output from the solar panel. Its even just for the components, its worth the money
So, yeah... I quite like this one