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BQ78350-R1: CEDV with a specific current profile

Pierrick Thevenaz
Prodigy 240 points
Part Number: BQ78350-R1
Other Parts Discussed in Thread: BQSTUDIO

Dear all,

I am using BQStudio in order to determine the CEDV parameters. Two different discharge at 3 different temperature is needed to do it.

I do not have constant current for the discharge but a current profile like the following:

15 minutes @30A -> 10 minutes @14A -> 5 minutes @19A -> ... -> 9 minutes @9A -> then 7A until the CUV ( aproximatively 1.5 hour @7A until CUV...).

So, my first discharge log will be with the current profile above. The second one should be the same profile with half of the current.

My question is : Do I have to multiply the time by 2 in order to have the same average consumption? I mean, divide the current of each step by 2 for two times the duration of the step. Otherwise, the last step will be 3.5A during 3 hour!

Best regards,

Pierrick.

  • 0
    TI__Intellectual 1840 points
    Hi,

    I think you may be confusing what the procedure is for obtaining the CEDV parameters.

    You are correct in that you need two different discharge profiles at 3 different temperatures. But this discharge profile is not going to be your application's current draw. We are try to obtain the CEDV parameters that correspond to your battery's profile. You simply need to draw a constant current out of your battery; this can be done using a sourcemeter, or attaching a constant load like a resistor to pull a constant current.

    www.ti.com/.../sluub45a.pdf

    Hope this helps,
  • 0 in reply to Nabil M
    Prodigy 240 points
    Hi,

    I do not think I am confusing if I refer to the application note you suggested.

    On page 2, paragraph 2.2 : "Discharge does not have to be constant current, it can be any load pattern typical for your application,
    including constant power. It is OK to have zero current rows before and after the discharge".

    Of course I can do it with a constant current, it does not matter for me, the process with an Electronic Load is the same. But if I have a load pattern, why do not use it?

    What is is the better way between the two methods? Or it doesn't matter which one I use?

    Thanks,
    Pierrick.
  • 0 in reply to Pierrick Thevenaz
    TI__Intellectual 1840 points

    Hi, 

    You are right. I apologize for that. I would guess that both should be fine in that case. My intuition tells me that a high and low constant current is easier to define. But you can go ahead and use your current profile. 

    Thanks,