Building a DIY 8 cell battery charger with the TP4056.

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zastin17
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Building a DIY 8 cell battery charger with the TP4056.

So I thought this site would be a good place to ask this. I am wanting to build a 8× 18650 charger using the TP4056 board and a ATX power supply.

I have a couple questions questions.

1. Do I need to put a load on the 12v rail to get the 5v rail to output correctly? I saw this somewhere and I am not sure if its true.
2. What would be the best/most efficient way to wire all 8 boards up? Should I wire them all in parallel with 1 5v wire and 1 ground wire? or individually connected to separate 5v out? Or does it even matter for the speed of charging?

I will be using battery holders located here: https://www.aliexpress.com/item/18650-Battery-Holder-Plastic-Battery-Hol...

After thinking a little. Lets say my psu is 20 amps on the 5v rail. Would that mean I could connect up to 20 TP-4056 in parallel because each one used 1amp.

Edited by: zastin17 on 05/23/2017 - 16:40
travis
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Not to Segway—but just an FYI for the realitively rare 8 cell chargers—Klarus has a new model on KaiDomain…

http://www.kaidomain.com/p/S026048.KLARUS-C8-8-Slots-Charger-Capable-of-...USB-Equipment-And-Ni-MH-Ni-Cd-Li-ion-Batteries

“"A free people ought not only be armed and disciplined, but they should have sufficient arms and ammunition to maintain a status of independence from any who might attempt to abuse them, which would include their own government.””
-George Washington

snakebite
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that klarus is the same as the “blank” charger that was sent to me by nitecorn.
its decent as long as you dont overload the usb output.i put a 6.2v 5w zener across the +5 to the usb on mine.that way if it dies an item plugged into usb wont get nuked and the 5a fuse i added on the dc input will blow.
think of it as a nitecore i8 if they sold one.except it has 8 750ma independent channels.
as for the atx supply the regulation is done with feedback from +5.it should stay well regulated even with no load on +12 or +3.3
yes it is crossloaded but the 2 i use that way stay in spec.
+12,+3.3 not so good but i dont care about those.

MtnDon
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A lot of those cell holders are designed for flat top cells and won’t easily, if at all, take a button top, let alone a protected cell. Just be aware and don’t be too surprised if you order some and that’s what you get. Of course that may be fine if you only want to charge flat tops. I also have found the cells are difficult to remove at times as they fit so tightly. I have a couple that I lay a piece of 1/4” wide ribbon across before loading the cell. The ribbon gives an easy grip to pull on the cell.

snakebite
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those are decent holders.
but as mentioned they are best for flattops.
and remember that the tp4056 has no reverse polarity protection.
they die instantly if you make a mistake.
the quality of atx power supplies is all over the map too.
lots of ultrafire grade “gutless wonders” out there.it might say 20a but blow up grandly at 10.