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BQ34Z110EVM Data flash

Stuart Graham
Prodigy 165 points

Hello,

I have received a BQ34Z110EVM and also EV2300 USB converter and i am trying to configure the EVM to work with a 110Ah 24v battery pack.

I have completed the calibration section OK.

Is there somewhere i can set the number of cells (ie 12)?   Also, i cannot set a mAh value any higher than 32767mAh.

Not 100% sure what parameters need to be setup, but the system will run under the following condistions.  

Charge current 0.5-4.5A  and discharge current will be 0.75A -3A.   The load is resistive (neither constant power or constant current).   I would want the battery to be regarded as empty when the voltage is 22.00v or below.

I would appreciate any help you can offer.

  • 0
    Prodigy 165 points

    Oops - just spotted the "Number of series cells" and changed this from 6 to 12.

    I think i need to enable the X10 mode, so i think i need to set the underlined values:

    Cell capacity mAh = 110000 /10 = 11000

    Cell capacity mWh = 110Ah x 24v x 1000 / 12 / 10 = 22000

    Cell BL = 22/12 x 1000 = 1833


    Not sure what to do with SOC1 Set and Clear, SOCF Set and Clear 

    Dont think i need to do anything with Charge Termination, Charge Inhibit 

     

  • 0 in reply to Stuart Graham
    TI__Guru 73830 points

    Stuart,

    It looks like you have answered your first set of questions correctly. SOC1 and SOCF are early warning flags to let the controlled know that the pack is getting close to empty. You can set the thresholds to capacity values where you want these flags to set. e.g. If you want the SOC1 flag to set when there is 150mA of Remaining capacity left, then set it to 150.

    Tom

  • 0 in reply to ThomasCosby
    Prodigy 165 points

    Hi,

    Thanks for your prompt reply,  that makes sense.   With the X10 mode, ive been reading another post where you said the X10 is just a reminder flag and has no effect in the calculations.

    Is it correct to say i would just need to enter 1/10th scale constants (eg 110Ah 11000mAh) as and recalibrate current also at 1/10th scale (eg set 100mA reading with 1000mA actual current applied), is this correct?

    Thanks,

    Stuart

  • 0 in reply to Stuart Graham
    TI__Guru 73830 points

    That is correct. The X10 Mode bit doe snot affect anything inside if the device. It is a flag to tell the controller that the pack has been scaled. You will scale all of the current and capacity parameters by the appropriate value and then scale the current by that value when calibrating the full scale current.

  • 0 in reply to ThomasCosby
    Prodigy 165 points

    Ok, perfect.  Will give that a try tomorrow and let you know how i get on.

    Thanks again,

    Stuart

  • 0 in reply to ThomasCosby
    Prodigy 165 points

    Hello,

    I think ive had good success with the manual scaling.   I now have the batteries on the anticipated load and its giving the results in minutes which i would expect so thats all good.  I have no set the X10 bit as im not sure exactly how, but i have set the Design Energy Scale to 10.

    Have got a few queries which im not clear on.....

    How does the x10 affect deadband and resolution?  I assume the 1mA resolution is now 10mA and the deadband is now 30-50mA as opposed to 3-5mA (with the EMV)?

    State of Charge 0x02/0x03.  I read 2, size 2 and get 6200  (0062 = 98% - correct, as reported)    I have never seen a decimal percentage, i assume its only giving integers and i could safely just read 0x02, size 1?

    I see in other posts you indicate a constant resistance is OK to use for the initial set-up, however my actual load in service is more constant resistance than constant current and is certainly not constant power.  I would assume in this case the best model to use is the constant current model?

    Last one for now....   I had set the maximim load current initial value to -100mA, however this is still reporting as -500mA and the time is being calcualted on this value, why is this?

    Thanks,

    Stuart

  • 0 in reply to Stuart Graham
    TI__Guru 73830 points

    Stuart, 

    Scaling will affect all current and capacity parameters, so the deadbands are a affected as well. The SOC is only reported as an integer, so the useful data is in the first byte. You can just read one byte from the device. Load Mode = 0 should work okay for your constant resistance load. I am not sure about the current reporting discrepancy. If you are using 10x scaling, then did you use a -2000mA discharge current and enter -200mA in the actual current field?

    Tom