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I am currently working on a project, which should contain a Li-Ion battery pack in the form of 8 18650 cells in 4S2P. The main consumers of the build are a class D amplifier and a single board computer, probably a Banana Pi Zero.

I would like to have a charger and balancer circuit integrated in the project, which would ideally be controllable in some form by the SBC. A charging voltage from 16V DC (or higher if needed) would be supplied by a power jack.

I have looked for charging and balancing ICs, the only suitable one I found, is the BG24702/3 from TI. It could handle the charging, but requires a huge amount of external circuitry.

Other ICs I’ve found, are only offered in QFN packages or similar. But I want to be able to solder everything by hand

Do you know a good and/or simple method for charging and/or balancing? Is it possible to get a simple CC/CV power source and then charge and balance periodically?

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  • \$\begingroup\$ Are you going to mass produce this or is it a one off? \$\endgroup\$
    – winny
    Commented Jan 28, 2019 at 12:28
  • \$\begingroup\$ Just a one off build. However, if the charging solution is good and universal, I would probably reuse it in some other projects, whenever I require such a battery pack \$\endgroup\$
    – Hendrik410
    Commented Jan 28, 2019 at 12:50
  • \$\begingroup\$ My best suggestion would be to use four floating 4.2 V CC/CV chargers, stacked in series. That will balance your batteries and charge them. Costly, but bulletproof. \$\endgroup\$
    – winny
    Commented Jan 28, 2019 at 12:58

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Here is an expensive but simple solution:

schematic

simulate this circuit – Schematic created using CircuitLab

I'll try to tidy up this...

If you don't want to charge from mains, substitute your AC/DC charger with a DC/DC one, but isolated/floating.

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  • \$\begingroup\$ You missed the live connection on one of those. \$\endgroup\$
    – Hearth
    Commented Jan 28, 2019 at 13:38
  • \$\begingroup\$ @Hearth IE does not play along nicely with the schematics editor. I’ll fix it. Thanks! \$\endgroup\$
    – winny
    Commented Jan 28, 2019 at 13:46
  • \$\begingroup\$ This looks good and straightforward. Would it be possible to create multiple isolated DC voltage levels from one DC input? \$\endgroup\$
    – Hendrik410
    Commented Jan 28, 2019 at 16:28
  • \$\begingroup\$ @Henrik410 Yes, that’s no issue. Are you in Sweden by any chance? \$\endgroup\$
    – winny
    Commented Jan 28, 2019 at 16:42
  • \$\begingroup\$ No, I'm from Germay \$\endgroup\$
    – Hendrik410
    Commented Jan 28, 2019 at 16:46

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