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I've searched my situation but cannot find my exact answer, I am trying to make 3S Li-Ion battery charger with 3 TP4056 Charger Module.

TP4056 Module 1A 5V one cell battery charger i thought if i use 3 of them i can build 3S battery charger, so i connected battery's balance leads to TP4056s

leads

But I noticed if I connect modules to one power supply GND's will be common and first charger module gets voltage of 3 cells (about 11v) and obviously this will lead problems, and I decided to power each TP4056 module from separate power supply, now each cell can be charged.

connection

My questions are:

1) Should i give up building this because charging batteries in series would cause problems?

2) Can cells wear out?

3) Cells become Unbalanced?

4) How can i power TP4056 modules just with one power source?

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  • \$\begingroup\$ Wow! I was literally trying this exact thing today and I blew up one of the modules. I guess I didn't see the battery I was charging going to destroy my module. Can you explain why having the charging modules input in parallel (common ground) destroyed one of the modules? I don't quite understand. \$\endgroup\$
    – cottsak
    Apr 12, 2015 at 13:15
  • \$\begingroup\$ Connecting this way cause a short circuit. Take a look at my question, my approach: electronics.stackexchange.com/questions/559530/… \$\endgroup\$
    – Codebeat
    Apr 11, 2021 at 6:29

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  1. I don't think this is by definition a wasted exercise to your developing interest in battery technologies. I do think there are better ways. There are charger ICs on the market for nearly any number of cells in series. But, if it's for testing your idea, this should be fine.

  2. Yes, but they will regardless of how you charge, discharge or store them. Just if you let them discharge below a certain level or charge over another level, they will degrade much faster. With an intelligent charger system, which I think your PCBs are, overcharging should be protected.

  3. In charging: No, in fact, they all get charged to full. In discharging yes. This can cause increased deterioration, which then makes them get out of balance faster, which causes a snowball effect. How can you prevent that? When they are in use, make sure they are protected from over-discharge. By this mean, each cell individually. Just checking if the total gets below 7V or 8V is not going to help, you need to have something that protects each cell from going below 2.5V. Here I note that some of these charge managers I mentioned also do this for you; they are a complete battery pack protection solution.

  4. You will need a set of isolated DC-DC converters. Which types are the cheapest depends on how and where you get them and where you are having them delivered, but many different manufacturers make DC-DC converters with 5V output at 100mA to over 20A. Just make sure they are fully isolated.

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  • \$\begingroup\$ Thank you, 1. I am experimenting, I know there is really cheap 3S solutions out there, thank you. 2. Batteries will wear out no matter what, I think there is no difference with this setup 4. Then with my setup, there is no need to converters but if i want to single power supply, then i need 3 DC-DC isolated converter. \$\endgroup\$
    – OSB
    Sep 29, 2014 at 20:41
  • \$\begingroup\$ You only need 2 DC/DC converters, you can power the first PCB with your "raw 5V". Saves money and total efficiency. When using lab power supplies, be very very aware about the earth connection of the power supplies. Most likely you will cause a short circuit for the supplies if it goes badly, but maybe something more destructive. Quite a few simple lab supplies without a separate earth on their front outputs have some optional or hardwired connection between the - and power earth. \$\endgroup\$
    – Asmyldof
    Sep 29, 2014 at 20:45
  • \$\begingroup\$ And, do stay alert about the discharge situation. If you cause a LiIon cell to reach below 1.5V weird stuff can potentially, theoretically start to happen in a stacked pack that may not be pleasant to the bystander. \$\endgroup\$
    – Asmyldof
    Sep 29, 2014 at 20:47
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looks like a 3S solution, maybe it will give you ideas:

http://www.instructables.com/id/Make-an-inexpensive-Lithium-Ion-Battery-Pack/?ALLSTEPS

also cct: http://www.batteryspace.com/pcmforli-coli-mn-nibatterypacks.aspx

rgds.

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    \$\begingroup\$ Can you add some more details from those links to your answer? Link-only answers are discouraged because they become useless if the links die in the future. \$\endgroup\$
    – PeterJ
    Apr 24, 2015 at 0:12
  • \$\begingroup\$ The indestructible one is only half a solution. The charging is done with a specialist balancing charger which isn't part of the project. \$\endgroup\$
    – John Stock
    Dec 15, 2023 at 22:23

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