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I was looking for 2-4 cell li-ion chargers like the Texas Instruments' BQ25798 [datasheet] and many others of this class.

They advertise that the IC can charge 1-4 cells, but balance charging is nowhere mentioned in its datasheet. From what I know, it is terribly unsafe to charge series li-ion cells without balancing. So what exactly is the BQ25798 offering?

Could it be that they leave the battery balancing for another IC like the Texas Instruments' bq29330 [datasheet]? Is that how it's done for multi-cell devices in production? Please point me in the right direction.

Thank you.

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    \$\begingroup\$ The BQ25798 is a 1 to 4 charger and, given that most applications use one cell, it is more cost effective to not put in facilities that are mostly not used. Plus, many balancing circuits are in built to the battery pack themselves and they don't want to pre-empt what external charge rate a user may choose and restrict their options. \$\endgroup\$
    – Andy aka
    Oct 1, 2021 at 10:57
  • \$\begingroup\$ Balancing circuits are often not charging but dissipating. \$\endgroup\$
    – DKNguyen
    Oct 1, 2021 at 13:38
  • \$\begingroup\$ Analog Devices some chips, LTC3300 or the LT8584, that do active balancing/charging through a multi-winding flyback. This of course involves custom magnetics so not really a good option at the hobby level, but really cool ICs... \$\endgroup\$
    – user187594
    Oct 1, 2021 at 14:53
  • \$\begingroup\$ @Stiddily Thank you for the answer. Do you know of any IC that charges multi-cell lipos and also balances them? \$\endgroup\$
    – Nirav
    Oct 2, 2021 at 10:39

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The chip you mention is for controlling the DC/DC converter that does the charging. It would be unwise to only use that chip for a Li-Ion system. You would have to combine that with the BQ769X series (7692 for 3-5, 7693 for 6-10, and 7694 for 11-15 cells). They may have chips for 1-2 cells, but I am not sure.

The BQ769X series is an Analog Front End that handles measuring individual cell voltages and can balance (up to 50mA or so) non-neighboring cells. You can even implement external balancing. You are, however, limited to switched resistive balancing. It is still up to the designer (you) to decide on a balancing algorithm.

Here's where it gets fun though... TI also has another IC that will handle the balancing algorithm for you, but you'll need ANOTHER IC to act as a fuel gauge as well.

It sounds like a nightmare, but it is much easier than designing all of this from scratch.

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