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BQ34Z100EVM: Chem ID selection tool not finding ID

Julian Eyre
Prodigy 240 points
Part Number: BQ34Z100EVM
Other Parts Discussed in Thread: BQ34Z100, BQ34110

I am trying to run a chem ID on a primary LiSO2 battery (BA 5590 B/U).

This type has a max OCV of 15V, consisting of 5 cells (3V each).

Capacity is 15Ah.

Termination voltage is 10V (2V per cell).

I ran the discharge test at C/10 as required and the results are attached.  I have also attached the ID test submission zip file.

However, I am only getting a very inaccurate match:

"Best chemical ID : 700 Best chemical ID max. deviation, % : 99.5

Accuracy Error: Deviation is so high that it is most likely due to anomaly in the data. Please check that data files have recommended format, units and test schedule"

There is no anomaly in the date that I can see, but this chemical ID is definitely not the correct one as it pertains to a Lithium Titanate rechargeable battery type.  I have not been able to find a LiSO2 battery type on the ID list, so am wondering if I am going to be able to ID this battery at all?

If not, what does 99.5% max deviation actually mean?  How will it affect the gauging accuracy if I use it as my ID? I.e. what will my max error be on my state of charge measurement?  Will I even be able to run a learning cycle?

JulianChem_ID_6.zipChem_ID_6-report.zip

  • 0
    TI__Mastermind 42535 points

    Hi Julian,

    The LISO2 chemistry is not supported by the bq34z100.

  • 0 in reply to Batt
    Prodigy 240 points

    Hi Batt,

    So my options are?

    We are now committed to using the BQ34Z100 for our multiple battery type monitoring system, so I need to get it to work with the LiSO2 primary battery types one way or another.

    We do not need high accuracy (we used to use just coulomb counting), so how would you advise that we use the system with that battery type?  Will there be any way of getting the system to learn the IT parameters by using a rough match on ID, for the discharge cycle only?  I know I can set the learn state to 5 to force a discharge learning cycle, as I did with our rechargeable batteries, but do you think this will work with the primary battery, even with a rough ID match?

    Or do you think I should just use the learnt parameters for the rechargeable batteries, and see how it works with the primary type?  What SOC accuracy would you expect by doing this?

    Regards,

    Julian

  • 0 in reply to Julian Eyre
    TI__Mastermind 42535 points

    Hi Julian,

    I'm so sorry that you got to know this at such a late stage.

    Yes, you can use coulomb counting. But the problem with the gauge is that it will take the IT reported values based on OCV that it gets off the OCV table. Those will be incompatible with your battery type and therefore the RSOC and FCC used will also be inaccurate. One solution to this is to use a CEDV gauge that coulomb counts and updates FCC based on a curve fit when EDV is reached. The bq34110 is a pin equivalent replacement for the bq34z100 and also uses CEDV. That may (emphasis on may) work but it may also have a lot more error. However, I'll have to check with systems about it. LiSO2 wasn't really a consideration when both these gauges were designed.

    Please don't use the larned parameters of the rechargeable battery with the primary cell. You can end up with > 50% RSOC error.