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BQ34Z100-G1: BQ34z100-g1 learning cycle

Gorka Lorea
Expert 1620 points
Part Number: BQ34Z100-G1

Hi,

I am doing a learning cycle for a BQ34z100-g1. I have a 8s LiFePO4 battery with charge voltage of 28800mV. 

I charge it to ful and the FC bit is set. Now it is suposed I have to wait the battery to relax and takes voltage measurement. 

However when I stop the charge at 29000mV the voltage does not estay stable. It slowly falls down to voltages around 28000mV (it takes about 1 hour to go from 29000 to 28000mV) and never VOK bit is cleared.

1. ¿When does teh BQ34z100-g1 takes the OCV measurements?

2. At 29000mV or when the battery is in a stable lower voltage (around 28000)? 

3. Once I was able to do it (I do not know how) and the max error change to 3% but it suddenly back to 100%. How is it posible the max error to come back to 100%?

Thakyou very much in advance,

  • 0
    TI__Guru* 76230 points
    1. It takes a qualified OCV for DOD0 which is used in calculated qmax when the dv/dt <4uuV/s condition is met. With LFP it is difficult to achieve especially after charge. Make sure to set the LFP relax bit in pack configuration B register. This will allow loneger periods of relaxation. Also, you will have to have longer relaxation periods after charging for your cells, not the typical 2 hours for other kinds of cels

    2. At the stable voltage.
    3. You may have reprogrammed your firmware or gg file back on the gauge other than that i don't see how max error would go back to 100%

    thanks
    Onyx