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BQ40z50-R1 learning cycle

user117843334
Prodigy 110 points
Other Parts Discussed in Thread: BQ40Z50-R1

Hello,


I'm trying to get the bq40z50-R1 works with my batteries and it fails. The learning cycle is never performed (LStatus stay at 0x4) even though the REST flag is to one after each charge/discharge.

I've attached the log of a discharge at ~C/10.

The batteries are 3.7V 500mAh 4S1P lipo with LiCoO2+C chemistry. So I let the default chemid, but if somebody could check what is the best match it would be really helpful.

I've attached the dump of the dataflash to help debugging this issue. Is there any obvious configuration issue for my setup ?


Thanks,


Philippe

7823.discharge.log.zipdata.gg.csv.zip

  • 0
    TI__Expert 6575 points
    The attached log file is quite limited. Is it possible to have all the Registers logged in a log file so that we can look at what is happening?
    In the meanwhile I will try to match the correct ChemID for your cells. It is most likely that the ChemID is not matched.
  • 0 in reply to Swaminathan Ramanathan75031
    Prodigy 110 points

    Here is a full cycle with all the registers logged.

    We can see that it was able to learn QMax (after 5 cycles), but the RSOC is clearly wrong. So the Chem ID is not the correct one.

    I have some questions:

    - Where you able to match a good chemistry ?
    - We can clearly see that battery 4 current reading is quite noisy, at 0mA (load and charger physically disconnected) we sometime read a current of 20-30mA on battery 4. Why ? I suspect this is the reason why the first learning cycles were unsuccessful as we are above the Quit() current. I'm using the development kit.

    - Why is the ChargingStatus.VCT bit never set ? MCHG get set but never VCT, why ? The current is below Charge term taper current (25mA) for more that 80s: From 02:42:43 to 02:49:08, the voltage is > 16800/4 on cell 4. And 2mAh passed into the battery (6minutes at ~20mA).


    Thank you for your support,


    Philippe

    fullcycle2.zip

  • 0 in reply to user117843334
    Prodigy 110 points

    Dear TI,

    Please, provide me the matching chemical ID, as the product is now ready to go in industrialization phase, the battery monitor is the only thing which is not working.

    I've been trying hard to get it work (several cycles, each of them taking 1 day on different devices), and it clearly seems that the chemical ID is the problem since the gauging estimation seems really not working according to last log.

    Do I need to contact somebody at TI in order to have this done ?

    Thanks,

    Philippe

  • 0 in reply to user117843334
    TI__Expert 6575 points
    Hi Philippe,
    I have run your log file through our ChemID selection tool. The best match is ChemID 189 (Max error 1.58%). Chem ID 3106 (Max error 2.06%) will also work.
    Swami
  • 0 in reply to Swaminathan Ramanathan75031
    Prodigy 110 points

    Hello Swami,


    Thanks for providing me the chemID.

    I did set it (189) and tried to run the two learning cycles. The first cycle went smoothly and the QMax is correct.

    But I'm unable to do the second cycle, LStatus is staying at 6. Here is my procedure:

    1) Fully charge until VCT (valid charge termination)

    2) wait until REST bit is set

    3) Discharge until FD (fully discharge) bit is set (when Vmin(cell) < 3V)

    4) Wait until REST bit is set


    Do you have an idea what I am doing wrong here ?

    I suspect the batteries voltage rise too high after FD, 3.3-3.4V, could it be a problem ?

    I've attached a log for a cycle.cycle-189.zip

    Thanks for your help !

    Philippe