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I believe the BQ24104 is the correct product to cover 3 Li-Ion cells ?

John Foley
Prodigy 70 points
Other Parts Discussed in Thread: BQ24104, BQ24170, BQ24133, BQ24115, BQ24113, BQ24105, BQ24125, BQ24123

I would appreciate any information I can get about using the BQ24104 chip to manage 3- Li-Ion cells.

I am powering two small device in a case.One Raspberry Pi and One 3 port USB 2.0 powered hub.

I am planning on using UltraFire 4000 mAh batteries with 3 in series with 2 sets of three in parallel, That should allow 8000 mAh of available current.

When accessing the information about the BQ24104, I do not see the circuit schematic for 3 cells.

I need to know if this chip will accept the current to charge two series of 3 cells?

Where can I go t get this information?  Thank you for help.

  • 0
    TI__Mastermind 20570 points
    The bq24104 only supports up to 2 cell battery charging. You can look at the bq24133 or the bq24170 which supports 3-cell battery charging.
  • 0 in reply to Jing Zou
    Prodigy 70 points

    The difference between the 24104 and the 24133 is monumental. The is no facility to include Charge state LEDs in this wiring diagram. I need a solution that can charge with a 5.0 volt DC adapter and has Charge display LEDs. Is there another that fits this bill?

  • 0 in reply to Jing Zou
    Prodigy 70 points

    I would really like to understand why the bq24104 data sheet specifically says 1-2 or 3 cells? When I look at the description, it says 1-2 or 3 cells?

    Am I reading something wrong?

  • 0 in reply to John Foley
    TI__Mastermind 20570 points
    Please refer to the table on page 4 for device options. The datasheet includes bq2410x and bq24113 /115. The bq24105 and bq24115 can be configured to 3-cell charging.
  • 0 in reply to Jing Zou
    Prodigy 70 points
    I will consider the bq24105 but when I am viewing the data sheets regarding the design components, I still only see versions of 1 and 2 cells.
    I need the LED charge indicators and to be able to charge the cells from 5.0 volts. Also another question - can two sets of 3 cells in parallel (six total cells) be charged with this one chip? Or perhaps I would need two complete sets of chip and components to cheat the second set of 3-cells. The end result is that I want 8000mAh with two sets of 4000Ah batteries to get convertted to 5.0 Volts.
  • 0 in reply to John Foley
    TI__Mastermind 20570 points
    Please read datasheet page 15 section 8.3.5 for output regulation voltage setting on bq24105.

    You can use the charger to charge two sets of 3-cell battery in parallel. However, the maximum output current is 2A. It will not able to charge the battery at 4A.

    The bq2410x series uses buck topology. It will not be able to charge the 3-cell battery with a 5-V input.
  • 0 in reply to Jing Zou
    Prodigy 70 points

    Then what about the BQ24125, it appears to be able to host 3 cells and is very much the same architecture as the 24105.

  • 0 in reply to John Foley
    TI__Mastermind 20570 points
    All of the chargers in our current portfolio uses buck topology. The input needs to be higher than the battery voltage in order to charge up the battery.
  • 0 in reply to Jing Zou
    Prodigy 70 points

    The line of battery chargers are very confusing. I keep finding new ones like the BQ24123 that seem to have the same chip technology but are configured for a specific application type.

    In each case I find that when a charger is capable of handling 3 cells, the schematic and design descriptions note one or two batteries with 4.2 of 8.4 volts.

    In the case of the 20FQN hardware it would seem that leaving pin 13 open defines one cell and adding a resistor to ground defines 2 cells, but there is no indication of how to define 3 cells in any of the documentation I have seen.

    I have switched from Linear Technology battery chargers to TI chargers IF I can ever define the one I need for my project. At the moment I think the BQ24123 may be the best one?

    My project is falling way behind it's ship date because of this and I need to order a product evaluation board for the right one.

  • 0 in reply to John Foley
    TI__Mastermind 20570 points
    From my understanding, you would like to use 5V input and charge up 3-cell battery. If this is the case, we do not currently have any released device that uses boost topology. If you have 19V input, then you can use either bq24105 or bq24125. These two devices can be configured to 3-cell charging by tying an resistor divider to FB. The voltage divider calculation can be found bq24105 datasheet page 15 section 8.3.5. Same applies to bq24125.