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BQ34Z100-G1: Please help with ChemID and battery learning cycle

Adrian Hallas
Prodigy 160 points
Part Number: BQ34Z100-G1
Other Parts Discussed in Thread: EV2400, BQSTUDIO, GPCCHEM

Hi,

We are going to be using the BQ34Z100PW-G1 in numerous products at medium production levels.  We need it to work with a number of LifePo4 batteries with differing Ahr ratings.  I have spent weeks attempting to successfully complete the battery learning cycle with no luck.   I urgently need help to resolve this or I am going to be forced to move to an alternative fuel gauge.  Can you please answer the following questions:

  1. Why does BQStudio present a warning saying that the BQ34Z100PW-G1 is not supported?  I am using the latest version of BQStudio and the latest firmware in the EV2400.
  2. What are the CC Offset and Calibration Offset shown in the calibration page of BQStudio?  There is no mention of these in the documentation.
  3. Is SLUA903 the correct document to be using for the learning cycle?  Paragraph 2.5 of this document states "
    quit current must be less than the Dsg Current Threshold and Chg Current Threshold."  This makes no sense when referencing the charge cycle diagram in the same document (see below).
  4. The battery datasheet does not provide a value for Charge Term Taper Current.  How should I get a value for this?
  5. Some of our units stop operating with 20% charge still remaining in the battery.  Do I only need to discharge to this level for the ChemID log file and for the battery learning process?
  6. I submitted the attached files to the online ChemID tool.  I got an error message saying no discharge cycle found, even though there is a "current" column containing negative values.
  7. I used the BQStudio logger to record the log file for the ChemID tool.  Was that the correct tool to use?

Would it be possible to get some help with the battery learning process?

Many thanks for your help,

Adrian Hallas

Research & Development Lead

BLE Lighting & Power Ltd

1351.roomtemp_rel_dis_rel.csv

Fullscreen 2248.config.txt Download 
ProcessingType = 2
NumCellSeries = 1
ElapsedTimeColumn=1
VoltageColumn = 2
CurrentColumn = 3
TemperatureColumn = 4

  • 0
    TI__Guru 60846 points

    #1: Please attach the screenshot when bqStudio shows the list of gauges when you start up bqStudio. It is important that bqStudio auto-detects the gauge without errors or warnings and I need to see the information from the startup dialog to know why this doesn't work.

    #2: CC Offset is automatically measured by the gauge when it enters sleep mode. bqStudio allows a forced CC Offset measurement. There is no need to adjust anything. When you select this option, the gauge will internally briefly short SRN and SRP and record the conversion result from the coulomb counter as the CC Offset.

    #3: The absolute value of quit current must be less than the absolute value of chg and dsg current threshold. These thresholds control the gauge state machine which must follow the state of the cell (charge, discharge, relax).

    #4: If this isn't in the datasheet then you must choose a setting. Typical is around C/15. Please make sure that your charger is configured accordingly.

    #5: No. For the learning cycle, it is irrelevant how deep you discharge the cell in your application. Depth of Discharge must change by at least 0.95, which means that passed charge during charging and discharging should exceed 95% of chemical capacity or in other words, please charge and discharge to the max/min from the cell datasheet.

    #6: It's likely because you have two very short charging cycles. The tool expects the discharge after charge but your file follows charge with charge.

    #7: Yes. You can use bqStudio. GPC works best if you start with a mostly discharged cell. Then charge it *once* to the maximum charging voltage (as specified for this cell) with a taper current of C/15 (example). Let it relax for 2 hours. Then discharge with C/5 down to the minimum voltage as specified by the cell datasheet. Let it relax for 2 hours.

  • 0 in reply to Dominik Hartl11
    Prodigy 160 points

    Hi Dominik,

    Thank you very much for your responses.

    #1:  I think the non-compatibility error message may have been due to starting BQStudio without power to the device.

    #2:  CC Offset now understood - thanks.

    #3:  Sorry, that was my misinterpretation.

    #4:  I don't have details for each of the chargers as they are bought in.  Do I need to get them?

    #5:  Understood - thanks.

    #6:  The charge, charge behaviour is down to the bought-in charger and I can't change it.  Shall I just delete the unwanted charge cycle from the file, or does this affect the relax period?

    #7:  Ok - thanks.

    Sorry, a couple more questions:

    #8:  Do I set all of the battery parameters in BQStudio and perform a calibration prior to logging the ChemID discharge cycle?  

    #9:  Is there a way to reset the BQ34Z100PW-G1 to factory settings or do I need to use a new one each time I attempt a leaning cycle?

    Many thanks for your help,

    Adrian

  • 0 in reply to Adrian Hallas
    Prodigy 160 points

    I have tried everything to get this device working, but the documentation is terrible and I can't get answers to my questions.  Is it too much to ask for a step by step process to get this working?  

     

  • 0 in reply to Adrian Hallas
    TI__Guru 60846 points

    Here is a quick step-by-step guide:

    1. Follow the quick start guide to get the EVM up and running. See Quickstart Guide for the bq34z100-G1Texas Instrumentshttps://www.ti.com › lit › pdf › sluubv2

    2. Perform a controlled charge/relax/discharge/relax sequence with a single cell (not the whole battery) and obtain a ChemID as described in GPCCHEM Application software & frameworkTexas Instrumentshttps://www.ti.com › tool › GPCCHEM. Note that it is not necessary to configure the gauge at this point. The EVM doesn't need to be calibrated and all you do is use the gauge as a current, voltage, temperature measurement device. Connect your almost but not fully discharged cell, a thermistor (attached to the cell), a charger and a load to the EVM, the EVM to a PC via EV2400 and launch bqStudio (which must auto-detect the EVM). Then click on Register Log and perform the steps from the GPCCHEM user's guide.

    3. Use bqStudio, Chemistry option and load the ChemID from step #2

    4. Use the info from the TRM https://www.ti.com/lit/ug/sluubw5a/sluubw5a.pdf to set the following:
    * Set Load Mode and Load Select as appropriate for your application.
    * Set Dsg, Chg and Quit Current Thresholds. Note that these settings describe the state of the cell, not necessarily the state of your application. If you don't know how to set these, I recommend C/16 for Dsg and Chg and C/25 for Quit Current Threshold.
    * Set Qmax Cell 0 to Qmax (chemical capacity) from step #2
    * Set Update Status to 0x04
    * Set Avg I/P Last run to average load in your application
    * Set the Voltage Measurement and Calibration parameters as explained in 3.4. Auto-calibration is automatic so there isn't anything you need to do.
    * Set the charge termination parameters as explained in 3.7. This is important because it defines the 100% SOC conditions.
    * Set Cell Terminate Voltage to the voltage under load where you want the gauge to report 0% SOC.

    4. Run a Learning Cycle as described in chapter 11, TRM

    About your questions:

    #1: bqStudio must auto-detect the gauge. If it doesn't, then it will either not communicate at all with the gauge (and nothing you configure in bqStudio will have an effect. bqStudio will show error messages in the status bar) or it may use incorrect addresses. The gauge must be powered up

    #4: You must know the minimum current when charging stops. This is important for valid charge termination. This information must come from your charger. The gauge doesn't provide this information, it needs this information. Taper Current should be set to about 10% higher than the current when charging stops.

    #6: The relax period is important because the gauge (and GPCCHEM) need a true open circuit voltage measurement to determine change in depth of discharge, which is one part of calculating chemical capacity. You can simply stop the charger for the required time (e.g. 2 hours).

    #8: For ChemID, you should use a single cell from your battery, connected to the EVM, configured for 1s. You do not need to perform any calibration nor do you need to set any battery parameters for generating the log file for GPCCHEM.

    #9: You can pull the original configuration from the gauge (via Golden Image in bqStudio) and re-program this with "Programming" which effectively resets the device to factory.

  • 0 in reply to Dominik Hartl11
    Prodigy 160 points

    Hi Dominik,

    Thanks so much for your detailed response - it's exactly what I needed.  I still have an outstanding issue with BQStudio not recognising the device:

    #1  Whenever I use a new EVM, connected to BQStudio through the EV2400, BQStudio doesn't recognise the device.  I then select BQ34Z100PW-G1 and accept the warning.  The next time I go into BQStudio the device is recognised.  I am using BQStudio 1.3.101,  EVM2400 firmware 0.32 and BQ34Z100PW-G1 firmware 2.01

    Your continuing support is very much appreciated.

    Kind Regards,

    Adrian

  • 0 in reply to Adrian Hallas
    TI__Guru 57697 points

    Hello Adrian,

    Please use the TEST version of bqStudio which is a newer version.

    Can you send a screenshot of the manual bqz selection screen when the EVM is not detected?