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BQ34Z100-G1: Learning cycle - full charge problem

Ben-478
Prodigy 110 points
Part Number: BQ34Z100-G1
Other Parts Discussed in Thread: GPCCHEM

Hi,

While attempting the learning cycle the full charge section failed.

The FC flag was set before the charge termination voltage was reached so charging was stopped. Also, SOC was reading 100%.

Also the VOK and QEN flags remained set after switching charge off. 

The update/learning status remains at 4.

I cannot understand why the FC flag was set early - could this be connected to a previous learning cycle being performed with different charge term voltage set. I dont know if a learning cycle has been performed already but am curious to know if that would somehow cause problems?

Once a successful learning cycle is completed the update/learning status should become 6 if I understand correctly, does it remain 6 indefinitely?

  • 0
    TI__Guru** 105760 points

    Hello,

    Have you followed the steps to upload your chemistry ID using GPCCHEM tool?

    Once the gauge learns Qmax and the Ra table the update status will remain at 0x06. It can change depending if the IT_EN is set also.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 110 points

    Hi Wyatt,

    Thanks, I managed to get a successful learning cycle. While setting up to do another I realised my notes were incomplete and Im unsure about setting up the Ra table flags.

    Am I correct that R_a0 and R_a0x should be set to 0xFFFF and 0xFF55? 

    If this is correct, which flag should be set to which value?

  • 0 in reply to Ben-478
    TI__Guru** 105760 points

    Hello Ben,

    The flags indicate which Ra table is active, the gauge alternates tables so the flash memory does not wear out since it is updated quite often. You do not need to set any of the Ra table or flags manually.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 110 points

    Hi Wyatt,

    Im having trouble again with the charge termination part of the learn cycle. I have made 3 attempts now, disconnecting the charger at different points, and it just keeps failing. The FC flag seems to set before reaching the charge term voltage and before the charge current even begins to taper off. 

    If I understand correctly the FC flag is supposed to set when charge term voltage and taper current have been satisfied. 

    I have tried 3 approaches (ignoring FC flag as it was set anyway):

    1. Waited for the current to taper off to a very low level before disconnecting charger

    2. Disconnected charger as soon as FC flag was set (within about 20 seconds)

    3. Disconnected charger once current had fallen below taper current (set to 100mA) for more than 60 seconds (I think it was a few minutes). This time I noticed that the OCVTAKEN flag had set just before I disconnected the charger, after that it reset again so I hoped it might work but left overnight it still didnt set again.

    Each of these result in the OCVTAKEN flag not setting so status remains at 4.

    The chem ID is right and all of the parameters that are considered important in "How to achieve a successful learning cycle" are set. Ive managed to do a cycle before so cant understand why its not working now. 

    The biggest question in my mind is why does the FC flag set so early, without the required conditions for it being met??

  • 0 in reply to Ben-478
    Prodigy 62 points

    Hi Ben,

    'FC set %' should be set to -1 for taper current-based charge termination. If you have set it to 100 then the FC bit will toggle on the basis of SOC % which would not be accurate in the learning cycle phase.

    This is what I have experienced in my attempt at learning cycle. I hope it may help.