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Four 18650 cells from power tool batteries - Vruzend end caps and nickel strips - and a USB power bank PCB from eBay.
NOTE: This power bank PCB charges the cells to over 4.3V - I don't recommend it.
https://odysee.com/ @julian256:d/first-look-vruzend-1-6-lithium-ion-18650:2
https://odysee.com/ @julian256:d/building-a-4s2p-lithium-ion-18650:0
5V 2A Type-c USB LED Lithium Li-ion 18650 Battery Charger Module DIY Power Bank https://ebay.us/eK9GNl

By Julian

Youtuber, shed dweller, solar charge controller aficionado

12 thoughts on “Build a usb power bank part 2”
  1. Avataaar/Circle Created with python_avatars spotify95 says:

    Also, that battery PCB must be made for LiHV cells, which have a 4.35V (or even 4.4V) termination voltage. I know some Li-Ion or Li-Po batteries do have a termination voltage of 4.4V as my HP OMEN laptop battery is 4.4V per cell at full charge/17.6V total. This also explains why the battery was showing as 0% even at 3.4V – it should show 0% somewhere around the 3V mark.

  2. Avataaar/Circle Created with python_avatars spotify95 says:

    1300mAh is pretty low for an 18650; they must be high current ones from a power tool?
    Quite often you can get 2200mAh or 2600mAh cells; these come from laptop battery packs, though you can buy them new if you want.
    Maximum is 3400mAh or 3500mAh, depending on the company.

  3. Avataaar/Circle Created with python_avatars Farley Hill says:

    Google image search for asc8826 JIAXC for a readable diagram.

  4. Avataaar/Circle Created with python_avatars noSafetySwitch says:

    Interesting little project! I happen to be building a QC 2.0 charger these days and it is very interesting to get under the hood of what is going on. You could try and build one yourself using the standard application schematic of many chips. Basically it is just a boost converter and an 8pin charge control chip that handles all the "talking" with the phone and just introduces or removes resistors to the boost converter's feedback to panipulate the output voltage. Sounds challenging but it is not that much and you end up having exactly the kind of charger you need. I also use salvaged 18650 cells nad what is best, they are charged by 2 x 20w solar panels so it does not get more eco-friendly than that. Keep it up!

  5. Avataaar/Circle Created with python_avatars Chris Hartley says:

    Is it possibly measuring Watt hours, to 1 dp. The full capacity of those batteries would be around 4.8Wh, which would be about right if the batteries were not fully discharged at the start.

  6. Avataaar/Circle Created with python_avatars Prem Nandpal says:

    your understanding to toooooo great !!

  7. Avataaar/Circle Created with python_avatars Glen W says:

    If you want to see what voltage it charges up to you could try replacing the batteries with a capacitor.

  8. Avataaar/Circle Created with python_avatars Daves Tech says:

    .04 volts isn't going to be a killer. How accurate is your meter? Does it have fast charge ability at 9 volts output?

  9. Avataaar/Circle Created with python_avatars andymouse123 says:

    You review this stuff so we don't have to !…..seems this one is a bit pooie…cheers.

  10. Avataaar/Circle Created with python_avatars Simon Howroyd says:

    Some mechanical strengthening might be wise. I can see those pads getting ripped off on the PCB due to the rotational stress of plugging in usb cables over and over?

  11. Avataaar/Circle Created with python_avatars LordGryllwotth says:

    Yes. In Aliexpress you can find sellers that sells these boards that can handle every protocol out there, I think!
    I just wish if I could get like a 4 cell in series or more charger, maybe it is more efficient to convert voltage down than up if you are going to use it for like giving 12v output on the USB -C port over PD-Protocol!

    You can get these small female USB-C that you program what voltage the charger should put out! You could like use it for a 12v radio or the like!

  12. Avataaar/Circle Created with python_avatars Haul'N Grass says:

    I believe if it’s less than 10% charged then it flashes. That’s what one of my power banks does.

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