I know a similar question was asked before, but still, it didn't aswer what I'm looking for.

I need to charge a series of 6 Li-ion cells, and maybe 12 in the future for a voltage hungry project. Since a have a bunch of TP4056 modules laying around, i want to use them as my charger.

I have encountered my self with the very wrong idea of connecting them in parallel to 5V, others say to just hook them up in series, but the drivers need a constant 5V input.

What about chaining zener diodes?

Or even better, i have switching regulatos modules, can i chain them as well, intead?

And what about building a multi-output 5V supply? (like a phone charger, but with isolated USBs, for example)

I don't need much correct out of them, 500mA overall per module would be fine.

(Over complicated, i know, but believe me, it's easier for me to get that done instead of getting a proper charger in my country.)

Here's the concept, these regulators could be any style of voltage regultor that fit the requirements. Also, this chain could be as long as needed (in my case, 6 to 12 cells) enter image description here

  • \$\begingroup\$ The most likely reason the existing question didn't answer your need is the simple fact that what you want to do is not practically workable. This is not how series packs are charged, period. \$\endgroup\$ – Chris Stratton Jul 27 '20 at 0:36
  • \$\begingroup\$ Thanks for all the help, i just had this question in my head. I'm still reading more in depth about battery balancing — Because curiosity! ♥️ \$\endgroup\$ – Rhodexa Jul 27 '20 at 0:43

You can use one TP4056 module per cell, but you will have to use fully isolated power supplies for each one. This would require one USB charger per cell and you would have to verify that each charger is isolated (put a 10K resistor between the grounds of the chargers and then measure the voltage across the resistor, is should be 0V if the power supplies are isolated).

With the availability of cheap chargers for RC batteries you would be much better off just buying an RC balancing battery charger.

  • \$\begingroup\$ As i replayed above, my plan to "Isolate the modules" is using a high voltage as main input, and balance 5V for every charger module. \$\endgroup\$ – Rhodexa Jul 27 '20 at 0:08
  • \$\begingroup\$ Using a 25V power supply and 5V regulators for each module will not work unless the 5V regulators are fully isolated ones. Standard buck converters are not isolated. This is just a bad idea, unless you have constraints you have not presented, just purchase an RC balancing battery charger. Using non-isolated converters will short the cells and possible cause a spectacular fire. Lion battery charging is not a good application to use to learn electronics. \$\endgroup\$ – Dean Franks Jul 27 '20 at 0:13
  • \$\begingroup\$ I added an image to explain my craziness \$\endgroup\$ – Rhodexa Jul 27 '20 at 0:23

You are correct in interpreting the spec of 5V for 4.2 CV with an input power dropping resistor to bring the input to 4.3 or more at max current. Thus a series connection is not possible from a single source.

However, nothing indicates a problem duplicating the layout in parallel if your source can handle the current such as from a PC PSU using 6A max for 6 cells.

  • \$\begingroup\$ I forgot to say, I'm planning to use a 25V power supply, and regulate 5V for evey module \$\endgroup\$ – Rhodexa Jul 27 '20 at 0:07
  • \$\begingroup\$ Is that worth the trouble? \$\endgroup\$ – Tony Stewart EE75 Jul 27 '20 at 0:08
  • \$\begingroup\$ I can, post a schematic of what i mean, if you want it. Could be easier :) \$\endgroup\$ – Rhodexa Jul 27 '20 at 0:09
  • \$\begingroup\$ For a first try of this quarantine project, yes, it worths it 😅 \$\endgroup\$ – Rhodexa Jul 27 '20 at 0:12
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    \$\begingroup\$ I get it, is like shifting the problem somewhere else. \$\endgroup\$ – Rhodexa Jul 27 '20 at 0:30

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