CCS/BQ40Z60: abnormal avg time to empty-continued

Emma Wang_DELL EMC

Part Number: BQ40Z60
Other Parts Discussed in Thread: BQSTUDIO

Tool/software: Code Composer Studio

Background: In my application, cell is charged to 3.8V(that is full charged I configure), then charge FET is open, TCA sets 1. After that, I don't discharge cell, gauging status is 5A, and current() is always 0.00A. But Ag time to empty changes to 49020 or 39216 and doesn't keep 65535. In our application, quit current is 40mA. Could you give me some advice about this phenomenon?

1, Doesn't avg time to empty run and keep 65535 when avg current is -10mA because FG is in relax mode? As I know, avg time to empty only runs in discharge mode.

2, How often does avg time to empty update?

3, The log file is from BQ log file indirectly. I highlight useful data in YELLOW. Could you help analyze this log, and tell me why this problem happen? Sorry i don't have chance to test using FG internal log. I can simply describe this log to you. avg time to empty varies 49020 or 39216. At the same time, current() is still 0.00A. Gauging status becomes 5A. State of charge keeps 100%. What else information do you need?

From this log and statement you said, 49020 only happens in discharge mode that mean current() is below -40mA. However, actual current() in log is still 0.00, which doesn't match what you said before.

Could you tell me why ?

3362.Taurus_BBU_FW_1v60_Time-to-empty-errors_73h-highlights (1).xlsx

4, I also want to know charger action after cell is fully charged. Are both FET for charger open? What configuration impacts charger performance after fully charged? how?

Thanks very much!

over 5 years ago

0 Andy Liu (BMS) over 5 years ago

TI__Guru 52115 points

Hi Emma,

Can you provide a bqStudio log file and gg file? The gauge device has a lot of infomation. With a bqStudio log file, it would be much eaiser for us to help you. Otherwise, we probably have to guess what's wrong.

Andy

0 Emma Wang_DELL EMC over 5 years ago in reply to Andy Liu (BMS)

Intellectual 695 points

hi Andy:

Does 'run time to empty' rely on 'current()'? When 'current()' is >=0, run time to empty is 65535. Otherwise, it changes according to 'current()'. Am I right?

log file has been attached in last chat. i attach it again.

7737.Taurus_BBU_FW_1v60_Time-to-empty-errors_73h-highlights (1).xlsx

And at the same time, i also attach configuration file.

7_19_6_3 version.gg.csv

Look forward to your quick reply. thanks.

0 Emma Wang_DELL EMC over 5 years ago in reply to Emma Wang_DELL EMC

Intellectual 695 points

Hi Andy:

Do you have any idea about this issue?

Thanks!

0 Emma Wang_DELL EMC over 5 years ago in reply to Emma Wang_DELL EMC

Intellectual 695 points

my current() reading resolution maybe not enough only 0.00A. So current() reading and run time to empty() reading can match. When run time to empty() isn’t 65535 after full charge, current() is about -1~-9 mA.

I found not all boards have this issue and some boards have at different temp.

078-000-109-02(ACPAG192400064) has this issue at 5C, 25C and 50C.

078-000-109-01(SN: ACPAG185100139) has this issue at 35C.

Time to full of 078-000-109-02（ACPAG192400056）will become smaller not 65535 after full charge at 50C.

So I think this maybe one issue about current() reading that maybe not inaccurate because of noise or inaccurate calibration for some batch board. Please give me your advice! Is my thought right? If yes, how to solve this? Doing calibration again or other method? If doing calibration again, please share me introduction or document about how to do calibration(including CC offset, board offset, voltage, current ,temp).

0 Andy Liu (BMS) over 5 years ago in reply to Emma Wang_DELL EMC

TI__Guru 52115 points

I would need to close it for now since it is a duplicate thread.

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CCS/BQ40Z60: abnormal avg time to empty-continued