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usb 18650 charger on the cheap

Discussion in 'DIY' started by jojo monkey, Jun 8, 2016.

  1. jojo monkey

    jojo monkey Well-Known Member

    Messages:
    387
    Found this great vid on youtube:

    Click to play YouTube Video


    Basically you need a $3-$5 tp4065 board and solder that to a battery holder.
     
  2. KeroZen

    KeroZen Chronic vapaholic

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    On Air
    They are now under $1 on aliexpress. Fasttech has two models but they are mini USB instead of micro USB. You can even adjust the charging current by replacing a single resistor. Nice stuff indeed.

    But for almost the same price you can get the chip inside a plastic battery holder, like this: http://www.aliexpress.com/item/Best...551219058.html?spm=2114.13010608.0.125.SLaJBQ

    You might argue that it isn't DIY anymore tho... :p
     
    jojo monkey and pandaphysics like this.
  3. KeroZen

    KeroZen Chronic vapaholic

    Messages:
    1,620
    Location:
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    A quick update as I received the two items in question:

    - The integrated charger / power-bank works very well, provided you don't get a lemon of course (see below)

    [​IMG]

    Build quality is on the low side, but it's as expected a very small board which is in fact more featured than just a simple TP4056 as the device can operate as a power bank (it's main intended use in fact)

    So it must have a step-up regulator on the output side, but I wouldn't trust it as a power bank using a high discharge non protected cell as in the picture above.

    But as a charger it works fine, at least this particular unit is. The cut-off voltage is slightly higher than on my evic VTC mini, usually around 4.12-4.15V depending on the cell. I measured it several times when I started using it, to make sure it wasn't going to ruin my cells, but it's fine and quite on the safe side. Note that it's not charging them as high as my Nitecore i2 which can properly top them off to 4.19-4.20V.

    It's of course generating some heat during charge but they seem to use the USB port ground as a heatsink and there's no concern here. The only drawback is that I can't use the provided lid as when it clips it's bloody hard to remove, so clearly not worth it to close it, I just leave it open like that. I think they really meant the thing to be used with a protected cell in a "seal and forget" fashion as a simple USB power bank to charge phones etc...

    So I do recommend this device as a backup charger. As always with Li-XXX charging, never ever leave the charger unattended. Always unplug them when you leave your house, you never know when those things will go wrong, and when they do it's not pretty!

    ---

    - Talking about not pretty, I also ordered a TP4056 board from China. I took the version with a micro USB port that is not the one pictured on the video above. It's the one having VCC/GND outputs in order to be daisy-chained, but it's also a clone of a clone, not even using the genuine TP4056 chip (as nearly all these Chinese board do in fact, including the two ones from Fasttech)

    [​IMG]

    I made a simple test setup and it appeared to kind of work, but the LEDs on the device... yeah I don't know, it wasn't clear, sometimes it stayed on blue, sometimes it stayed on red. When nothing was plugged it was blue with a fast flashing red...

    [​IMG]

    But yeah, I left it in front of me for a while, and the cell voltage didn't seem to change at all. In fact it was dropping slowly in one case... so I fiddled with it and couldn't manage to make it work. Now I don't know if it is due to user error (not likely, I know those contacts using alligator clips and rare earth magnets are not optimal, but it's just 1A of CC) or if I got a dud, but I re-tested it the other day... and bingo got the magic smoke starting, the board is toast! I unplugged it before it could catch fire but it was already smelly and too hot to touch... (note that this time I was using a proper 18650 plastic cell holder and good contacts)

    So hm, buy Chinese buy twice they say! I got the first one for $0.37 shipping included, and I said fuck it, I'll get another one! I ordered the same board from another shop for $0.34 this time haha. I'll report later on. But really, I'm sure that when you get a good one they do work, there are literally thousands of positive reviews for these products both on aliexpress and Fasttech, many independent people published reviews of them, they might not be the most accurate but they do the job and follow the CC/CV charging logic properly.

    Anyways, please be careful with these things. Always double check the voltages and if they cutoff when they should. Stay around them for the first 5 or 10 charges, just to be sure they are working fine (with Chinese crap, it's the customer that does the QC!) and afterwards it's fine. I'm sure you could even include one of those inside a single cell portable vape product to add USB charging capability.

    PS: important detail, they can be daisy chained only to create a multi-slot charger, you can't use them to charge cells in series.
     
    Last edited: Sep 30, 2016

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