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bq34z100-G1 setup

Lambert de Wet
Prodigy 40 points
Other Parts Discussed in Thread: BQ34Z100, BQ34110, BQ34Z100-G1

Hi

I am pretty new to the TI battery management systems. I need to configure the bq34z100-G1 chip to work with our battery pack. We use CA180FI CALB cells. We have two parallel legs each made up of 27 cells connected in Series. This gives us a pack voltage of nominal 86V and a capacity of 360Ah.

I have created a voltage divider circuit to step the voltage down to 900mV and I have a current shunt of 0.3mOhm (250A, 75mV). I am unsure of the process to follow to ensure accurate SOC measurement and have the following questions:

1. Can I use the CA60FI CALB chemistry (ID0443) for this application?

2. Can I use the current shunt for my current measurement on the bq chip? Do I have to update any values in the configuration file?

3. Where / how do I indicate the rated battery capacity to the bq chip? Do I need to do this?

4. I have looked at a post in this forum (BQ34Z100 battery capacity). There they talk about battery learning. I have tried to find more information on that, but could only find a pdf from 2009. Is this still applicable? If yes, could you please refer me to the documentation stating how this should be done?

5. What would be the process to get to accurate SOC measurement?

Thanks in anticipation

Kind regards

Lambert de Wet

  • 0
    TI__Guru 73830 points
    Lambert,
    You can use the bq34z100-G1 with LiFePO4 cells, but the bq34110 may be a better option. It is a CEDV gauge that does not depend on the OCV for gauging. LiFePO4 cells have very flat discharge voltage profiles and this poses some limitation for IT gauges. The bq34110 should be released by the end of November and a preliminary datasheet is on the web. The voltage range on the sense resistor interface is +/- 125mV, so you can use a larger vlaue sense resistor to use more of the range. The IT gauge uses QMax as the measured no-load capacity of the cell. It uses FCC as the usable capacity and RemCap as the capacity at the present state of charge. The CEDV gauge does not use Qmax and just uses FCC and RemCap. There is a lot of information on our Battery Management University website and a 365 page application book can be downloaded from the bq20z95 website and it provides a lot of information on IT.
    Tom