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BQ24650: Charging multi-cell LiPo batteries without cell balancing

Pero Krivic
Prodigy 60 points
Part Number: BQ24650
Other Parts Discussed in Thread: BQ40Z50, BQ25887

The datasheet of this part specifies multi-cell charging a couple of times throughout the text, but never does it mention a problem of cell-balancing. How come? Should a designer devise a circuit on its own or is BQ24650 somehow compatible with multi-cell batteries?

BR

  • 0
    TI__Mastermind 24075 points

    Hi Pero,

      The configurable charge regulation voltage allows us to support multiple battery chemistries but if the designer wants to use cell balancing they will have to include an external balancing circuit.

    Here is a link to our portfolio of balancers: http://www.ti.com/power-management/battery-management/monitors-balancers/overview.html

  • 0 in reply to Kedar Manishankar
    Prodigy 60 points

    Hello Kedar,

    thanks for the response. So, the charger can not make sure all cells are balanced i.e. draining each other. So, when you advertise this product as a "multi-cell" charger, how can you guarantee this will not be a hazard for battery? Why don't you provide a safety solution that includes cell balancers?

    Best regards,

    Pero

  • 0 in reply to Pero Krivic
    TI__Mastermind 24075 points

    Hi Pero,

       A "multi-cell" charger has the capability to charge multiple cells. We have chargers that also perform integrated cell balancing but these are explicitly mentioned (example: BQ25887). This charger has protection for overcurrent and overvoltage events on the battery (as well as other fault protection mechanisms) but an engineer should also sure that they have external protection. For example battery packs are highly recommended. Also most gauges have integrated cell balancing for multi-cell (see BQ40z50), and chargers usually go hand in hand with gauges when engineers design battery systems.

    Cell balancing is a system/application level decision.  Cell balancing keeps all of the series batteries at a higher capacity for a longer lifetime (i.e. more recharge cycles).  If the system doesn't require the batteries to be frequently discharged and recharged (e.g. battery backup) and/or cost to replace the expired batteries is low then cell balancing is likely not needed. 

    Again all "multi-cell" chargers have the capability to charge multiple cells, and this is a common terminology. If you want cell balancing then take a look at the portfolio I linked above.

  • 0 in reply to Kedar Manishankar
    Prodigy 60 points

    Perfect explanation. Thanks, Kedar.

    Cheers,

    Pero