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Can the BQ78PL114/BQ76PL102 combination handle a 100S1P system of LiFePo?

Pierre Hinse
Prodigy 30 points
Other Parts Discussed in Thread: BQ76PL102, BQ78PL114, BQ76PL536

Can the BQ78PL114/BQ76PL102 combination handle a 100S1P system of LiFePo?

The page on HEV systems BMS links to the PL114, but the PL144 is rated to 12S maximum.

http://focus.ti.com/docs/solution/folders/print/599.html

To acheive the higher cell counts, what solutions does TI advise?

(With PowerPump balancing of course)

Seasons Greetings,

 

Pierre

 

 

  • 0
    TI__Intellectual 1430 points

    Hello Pierre,

    The bq78PL114 & bq76PL102 manage upto 12s cell battery packs.  To work with a greater number of cells in series, please look to the bq76PL536.

    http://focus.ti.com/docs/prod/folders/print/bq76pl536.html

    Regards,

    Matthew

  • 0 in reply to BatteryBorne
    Prodigy 30 points

    Thank you Matthew,

    The bq76PL536 seems interesting alas it's status is in preview.

    Would anyone know when it will be switched to production?

    The oher issue is that it uses a shunt type equalization, that is where the bq78PL114 was very interesting with PowerPump technology.

    Would you know if we grouped the cells into sub-packs of 12 cells, the respective bq78PL114's could be networked on the SMBus to monitor the full pack?

    Even while only equalizing accross the 12 cells monitored inside the sub-pack, and not across sub-packs.


    Regards,


    Pierre

  • 0 in reply to Pierre Hinse
    Expert 2135 points

    Yea, I was disappointed that the '536 used passive resistor balancing too. :(

    You can use multiple '114s but you'll need to use digital isolators on the SMBCLK and SMBDAT lines since each '114 will be sitting at very different voltages. Also, I believe, since there's no chip select function you'll have to have a separate SMBus to each '114. Otherwise all the '114s will get the commands at the same time.

    The total sense resistor voltage drop will have to be taken into account too since each '114 will have its own resistor and the total voltage drop might get pretty high with a high-voltage pack.

    John