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BQ34Z100-G1: BQ34z100-g1 learning problem

Gorka Lorea
Expert 1620 points
Part Number: BQ34Z100-G1

Hello,

I am using bq34z100-g1 with an 8 cell LiFePO4 and first of all I want to do the learning cycle. I have donde the following steps:

1. Enable IT

2. Charge the pack to full.

3. Let it relax for 2 hours. 

4. Discharge the pack to cell Termination Voltage (3000mV, equivalent to the pack being at 24V) and let it relax for 5 hours.

However the MaxError did not change to 5%, it is 3% and learned Status and Update Status is equal to 0x05.

Now I am repeating the cycle but I am afraid Max Error remains at 3%. What are the things I am not doing well?

Here you have the registers of the bq34z100-g1 in case they were useful. 

Thankyou very much in advance for your answers, 

  • 0
    TI__Guru* 76230 points
    You are doing everything well. with max error of 3, it means you have qmax has updated but resistance is yet to update. Once that occurs, max error will go to 1 and update status would be 06. To have a successful update of resistance, you need to make sure your chem id which you are using is correct and you have to make sure you are using a discharge current between c/5 and c/10... It is preferable to use c/7
    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Expert 1620 points
    Hi Onyx,

    1. In what moment is the resistance updating?
    2. During the discharge at c/7 rate? Is there any other condition I have to take into account?
    3. How often is updating the resistance during discharge?
    3. Wich parameters are going to tell me the device is ready to update the table resistance?
    4. How can I now the resistance is already updated?

    Thankyou very much in advance for your answers,
  • 0 in reply to Gorka Lorea
    TI__Guru* 76230 points
    Hello Gorka,
    1. Resistance updates occur only during discharge. Resistance updates to data flash occur only after you have been in a discharge state for 500s.
    2. No condition, just dicharge using a constant current after your 2 hour relaxation time has elapsed after charge.
    3. There are 15 grid points, the first 8 are equally spaced while the last 6 are equally spaced. When the gauge updates one grid point, the rest of the table is updated as well via extrapolation.
    4. Just after your 2 hour rest, discharge can be started.
    5. Your resistance table would be different from the resistance table you started out with. also Ra flag will be 0055 on atleast one of the tables.

    thanks
    Onyx