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Would bq34z110 be able to work with a 200Ah 2V cell?

Hac Le
Intellectual 670 points
Other Parts Discussed in Thread: BQ34Z110, BQ34Z100-G1, BQ76PL536EVM-3

Hi all,

I'm planning to work with the BQ34Z110EVM board to development a full-fledged battery management system. However, I wonder whether I could use the board with a 200 Ah Lead acid cell or not? Scrolling around the forums gives me the impression that I could do this by a current scaling scheme, but there is no official guide on this, isn't there? 

BQ34Z110 limits the minimum cell voltage to 4 V, so this means I have to string two 2V cells in series in order to get the chip to function correctly?

  • 0
    TI__Guru 73830 points

    We do not have an application note to cover these special cases, but I am scheduled to release one this year. You can use capacity and current scaling to support your 200Ah requirement and thank you for looking for searching the forum.

    The device should be able to support 2s PbA pack. You should try to keep the minimum stack voltage above 3V.

  • 0 in reply to ThomasCosby
    Intellectual 670 points

    Hi Thomas,

    Thank you for the reply. 

    I also read into the EM1401EVM board's docs and saw that it supports 2 V battery cell. The obvious problem of this board with my project is that it only supports Li-ion cells. So, in theory, can I use EM1401EVM for lead acid cells or NiCad cells? I know that I will have problems with SOC and SOH accuracy, what is the error margin that I am looking at?

  • 0 in reply to Hac Le
    TI__Intellectual 2795 points

    The EM1401EVM uses the EMB1432 AFE, which can accept a 0-5V input for measurement. The input ABS max is 6V. This solution was not designed for Pb cells. Nicad would be acceptable.

  • 0 in reply to Stephen Holland
    Intellectual 670 points

    Thanks Stephen,

    One final thing, it is said that the bq34z100-G1 supports I2C communication, the logical next step would be to string many bq34z boards together, set them to slave mode, transfer data to an ARM master (I have the F28M35 for this job), and the master will then upload data to a GUI on a PC for system monitoring. Does TI fully support this communication setup for the bq34z?

  • 0 in reply to Hac Le
    TI__Guru 73830 points
    The I2C address is fixed at AA, so you will need to use an I2C multiplexer if you want to communicate with more than one bq34z100-G1 device.
  • 0 in reply to ThomasCosby
    Intellectual 670 points

    Thomas, thanks a lot for the heads up. With this information, I think I will drop the bq34z option for my project since I would want something that support modularity at the very beginning. What about BQ76PL536EVM-3? Is there any slim chance that this board will somehow support Lead Acid and master slave communication?

  • 0 in reply to Hac Le
    TI__Guru 73830 points
    We do not have any cell protector devices that will support PbA cells. They all work in the Lithium cell voltage range.