Other Parts Discussed in Thread: BQ34Z100, BQSTUDIO
Hello,
we are working on a design with our customer to get bq34Z100G1 up and running with a S5 NiMH configuration. Chem Id has been determined using the suggested algorithm.
There have been some issues with the BQ34Z100G1 chip and its battery capacity readings in relation with the Impedance Track Algorithm.
Firstly, The chip is showing a full charge capacity of 13784mAh although in the Data Memory this has been set to 18000mAh. I’m using a 100mOhm sense resistor so the figure has been scaled by a factor of 10. I have carried out numerous charge/discharge cycles but this value still the same.
Secondly, I have followed the ‘Impedance Track Configuration’ section (Appendix D) in the Technical reference to correctly set up the chip. I have set up the Chem ID as per advised and proceeded with performing the learning cycle. During this cycle, the chip is supposed to update a register named ‘Update Status’ which contains the current status of the learning cycle. Normally, it is set to 0x04. The value of this register is supposed to change to 0x05 following a 2-hour relaxation after a full charge. However, I found that this register was not updated. As a result, the learning cycle was not successful.
According to the ‘Technical Reference’, this problem means that a full charge was not detected:
(D.4 Common Problems Seen During the learning cycle)
It mentions 3 criteria by which the gauge detects a full charge condition. However, these conditions are not applicable to NiMH batteries which uses –dV/dt and dT/dt to detect end of charge/full charge! Meaning that a learning cycle for NiMH batteries may never be completed.
Finally, while carrying out discharge cycles I’ve noticed a sudden drop in the battery capacity value to 0%. This has happened few times and I can’t explain why has it happened.
Can you please let me know your thoughts and how can we solve the above issues?
many thanks
Lutz
