• State TI Thinks Resolved
  • Locked Locked
  • Replies 14 replies
  • Answers 3 answers
  • Subscribers 63 subscribers
  • Views 679 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: Please clarify the meaning of these terms and their units

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

Hi,

slu450a discusses the Impedance Track algorithm for the bq2750x family.

Why isn't there a similar document for the BQ34Z100?

In the absence of this document, can you please clarify:

  1. The meaning of DOD0, it's units and when it is updated.
  2. The meaning of DoDatEOC, it's units and when it is updated.
  3. The calculation performed to update Qmax.

It's like trying to resolve issues blindfolded without this basic knowledge!

Many thanks,

Adrian

  • 0
    TI__Mastermind 26545 points

    Hi Adrian,

    This document is relevant for all Impedance Track gauges.

    DOD0 is the current DOD, DOD stands for depth of discharge, and is calculated using a function of constant voltage, taper current, and cell temp.

    DODatEOC is the DOD at the end of battery charge phase.

    This is a very complex question to answer, I recommend reading section 2.3 of the document you mentioned (linked below)

    Theory and Implementation of Impedance Track Battery Fuel-Gauging Algorithm (Rev. A)

    Regards,

    Evan

  • 0 in reply to Diego
    Prodigy 160 points

    Hi Even,

    I have read and understood slu450a, but I am having trouble relating the content to the parameters shown in BQStudio.  For example, slu450a states that:

    Qmax = PassedCharge / (DOD2 – DOD1)

    The value of DOD0 shown by BQStudio, before charge, was 16124.  After charge it was 57087.  How do I apply these values to the above formula?  What units are they in?

    Many thanks,

    Adrian

  • 0 in reply to Adrian Hallas
    TI__Mastermind 26545 points

    Hi Adrian,

    Qmax updates will be taken throughout discharge.

    DOD0 on BQstudio will report the depth of discharge at the most recent OCV reading. Multiple OCV reading are taken throughout discharge.

    Qmax is in mAh. DOD has no units

    Regards,

    Evan

  • 0 in reply to Diego
    Prodigy 160 points

    Hi Evan,

    If I am to stand any chance of resolving the erratic behaviour of the fuel gauge, that we are experiencing, I need to know the details of how it works.  Try putting some numbers into the QMax formula above using the units you gave - it doesn't make any sense.  Presumable the DODs should be in the range 0 - 1 and therefore the DOD readings from BQStudio should be divided by a constant.

    I don't understand why the parameters and  formulas used are not properly documented.  Is there any way of escalating this issue because, if I don't find a resolution soon, I will be ditching the TI fuel gauge in phase II of the project?

  • 0 in reply to Adrian Hallas
    TI__Mastermind 26545 points

    Hi Adrian,

    The Qmax displayed on BQstudio is the filtered Qmax, the filter Qmax equation is proprietary.

    Due to this there will be some difference in Qmax calculated and Qmax displayed on BQstudio.

    The values you sent above should be DOD1 and DOD2, passed charge is represented in BQstudio as DOD0 Passed Q, this should give you a rough Qmax value.

    If you are experiencing problems with the BQ34z100, can you please explain the problems you are having?

    Can you provide a BQstudio log file of the problem you are having?

    Regards,

    Evan

  • 0 in reply to Diego
    Prodigy 160 points

    Hi Evan,

    We have hundreds of units under test before being sent out, so I can't possibly log all of them.  I raised another ticket (which you replied to) about units reporting 0% charge when they are fully charged.  Here is a selection of oddballs from today's tests (recorded by our own system, not BQStudio).  After disconnecting and reconnecting the battery, these unit tests correctly.

  • 0 in reply to Adrian Hallas
    TI__Mastermind 26545 points

    Hi Adrian,

    Like I had previously stated in the last E2E thread this will be difficult without a full picture of what is happening.

    However, I have a few general solutions to this problem.

    Did you use the GPCCHEM tool to get a chemID match? Was the DOD error 3% or less?

    Did you perform a learning cycle on your battery? Did you reach learned status 0x06?

    Is VOLTSEL set?

    Regards,

    Evan

  • 0 in reply to Diego
    Prodigy 160 points

    Hi Evan,

    Diego said:
    Did you use the GPCCHEM tool to get a chemID match?

    Yes

    Diego said:
    Was the DOD error 3% or less?

    This is an extract from the GPC report:

    Best chemical ID : 487 Best chemical ID max. deviation, % : 13.72

    Summary of all IDs with max. DOD deviation below 15%

    Chem ID max DOD error, % Max R deviation, ratio
    487 13.72 0.73
    485 13.72 0.72

    Max. deviations for best ID is within recommended range. Chosen best chemical ID is suitable for programming the gauge.

    Diego said:
    Did you perform a learning cycle on your battery?

    Yes

    Diego said:
    Did you reach learned status 0x06?

    Yes

    Diego said:
    Is VOLTSEL set?

    No, we are not using series cells.

  • 0 in reply to Adrian Hallas
    TI__Mastermind 26545 points

    Hi Adrian,

    You will not get accurate SOC with a ChemID match with 13.72% DOD% error. In order to achieve accurate gauging, the DOD% error need to be 3% or less.

    You can do 2 things to fix this...

    1) try to redo your GPCCHEM charge/discharge cycle and see if a better ChemID match is obtained due to an error during the initial time using the tool.

    or

    2) you can get aa custom chemID made for your battery cell. Please reach out to your supporting FAE or local TI office to get this done. This will take about a month, to be completed.

    Regards,

    Evan

  • 0 in reply to Adrian Hallas
    TI__Mastermind 26545 points

    Hi Adrian,

    You will not get accurate SOC with a ChemID match with 13.72% DOD% error. In order to achieve accurate gauging, the DOD% error need to be 3% or less.

    You can do 2 things to fix this...

    1) try to redo your GPCCHEM charge/discharge cycle and see if a better ChemID match is obtained due to an error during the initial time using the tool.

    or

    2) you can get a custom chemID made for your battery cell. Please reach out to your supporting FAE or local TI office to get this done. This will take about a month, to be completed.

    Regards,

    Evan

  • 0 in reply to Diego
    Prodigy 160 points

    Hi Evan,

    I ran a new charge / discharge cycle and got the following from the GPCCHEM tool:

    Best chemical ID : 464    Best chemical ID max. deviation, % : 13.51

    Can you please let me know who to contact to get a custom ChemID (I am based in England)?

    Many thanks,

    Adrian

  • 0 in reply to Adrian Hallas
    TI__Mastermind 26545 points

    Hi Adrian,

    You can contact your local TI office or your supporting FAE. Please let me know if you have any trouble with this and we can discuss in private messages.

    Is your battery chemistry LiFePO4? This is chemistry is harder to match due to the long flat region on the OCV curve.

    Regards,

    Evan

  • 0 in reply to Diego
    Prodigy 160 points

    Hi Evan.  I have been unable to find contact details for my local TI office.  Can you please assist?  Yes, it is LifePo4.

  • 0 in reply to Adrian Hallas
    TI__Mastermind 26545 points

    Hi Adrian,

    I am closing this thread and sending you a friend request, there we can continue to discuss privately.

    Thanks,

    Evan