• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 62 subscribers
  • Views 451 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ34Z100-G1: BQ34z100-g1. SoC estimating after powered up

Gorka Lorea
Expert 1620 points
Part Number: BQ34Z100-G1


Hi, 

I am using the BQ34z100-g1 to estimate SoC of an 8s LiFePO4. As the gauge is not installed as a pack side gauge, it can lose power very occasionally (once in 6 months).

After recovering power supply and with the battery relaxed I send an enable IT command to the gauge to estimate SoC beacuse it restarts with a senseless SoC. I have some questions about this procedure. 

1. What is this estimation based on? OCVoltage?

2. if so, where  this relation OCV-SoC come from? from the ChemID file? or from data obtained in the learning cycles?

3. What error can I hope in this first estimation with LIFePo4 batterys (where the curve OCV-SoC is very flat)?

4. Is this relation OCV-SoC taking into account the temperature of the battery?

Thank you very much in advance, 

  • 0
    TI__Guru* 76230 points
    Hi Gorka,
    1. Yes, OCV voltage and average I last run. The gauge performs a rem cap simulation using that current. That current is used to determine FCC and then the SOC is estimated based on the DOD measurement of where you are on the OCV curve.
    2. CHem id file, qmax and resistance table. It isn't a simple OCV-DOD correlation
    3. Due to the flatness of LFP cells, it is very difficult to get reasonable SOC estimation so the SOC can't be trusted upon initialization. Only after discharging to full or empty so the gauge has a proper reference point for these kind of cells can the SOC be trusted.
    4. Yes it does.

    thanks
    Onyx