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Li-ion battery management question (bq20z95)

Neil Dominico
Prodigy 80 points
Other Parts Discussed in Thread: BQ24703, BQ2000, BQ24702, BQEVSW, BQ20Z90, BQ29330, BQMTESTER

Hi everyone,

I'm a newbie to battery management and would like a sanity check to see if I'm going along the right lines. Having read a few TI app notes, I'm about to purchase the bq20z95 EVM for my project. This is my general plan:

1) Purchase the bq20z95 EVM and the 2-cell battery pack I'm planning to use.

2) Connect the EVM to the terminals of the battery and computer.

3) Using the software, set a few flash settings for number of cells, pack capacity etc.

4) Then do a learning cycle (discharge and charge) which will allow the bq20 module to learn performance data specific to the type of battery I'll be using. I can then copy that flash data across to the other bq20 modules I plan to use, without doing another learning cycle.

Is this generally correct? What discharge and charge currents should I use for the learning cycle? Should I be using a dedicated Li-ion charger at this stage? If so, can you recommend one from TI?

Thanks!

Regards

Neil

  • TI__Expert 6470 points

    Hi Neil,

    Yes, thats the general idea. The more you can read in the app notebook the better. Consider using the bqEasy feature in the EVSW to take you through the whole process. At screen 3F, I recommend that you jump back to the DataFlash screen and make any additional changes.

    You can use any decent lab supply with current and voltage controls as a Li-ion charger. The learning cycle should be done with currents similar to your target application.

    Regards,

    Doug

  • in reply to Doug Williams4811
    Prodigy 80 points

    Hi Doug,

    I'll try the bqEasy feature, thanks!

    Another question I had - it seems that the maximum charge current offered by TI Li-ion chargers does not exceed 2A. I'm not sure if I should be posting this here though - if you want I'll rewrite this message in the charging section. I'm looking to charge at (a max of) 10A - would I have to custom build the charger for this?

    Regards

    Neil

  • in reply to Neil Dominico
    TI__Expert 6470 points

    The chargers with integrated FETs are for lower current applications. For higher currents, you can use bq2000, bq24702 or bq24703 with an external FET. Try the Charger forum for more information.

  • Prodigy 10 points

    Hello

    I have some kits BQ20Z90EVM

    I wrote a lot of software for this kit for Windows CE

    If it is needed I can help somebody....

     

    Thierry

  • in reply to Thierry Vorms
    TI__Intellectual 1955 points

    Hi Thierry,

    Thanks for your offer, please let me know if you need assistance on where or how to post code.  A lot of the other Community members have added it to their profile so other members can access it or send you questions.

    Regards,

    nancy!

     

    Happy New Year!

  • in reply to Thierry Vorms
    Prodigy 10 points

    Hi Thierry,

    I really got surprised when TI tech support told me they did not have any driver code for the bq EVA20z90 board. I plan to program the chips via the bqSW of course, and later to inquire the status of the pack (voltage, temperature, TOF) with the help the microcontroller. Do you happen to have any C code of that sort that you are willing to share? 

    Many thanks,

    Djordje

  • Prodigy 50 points

    I want to do a small lot of bq20z95, Does anyone know where I can download the bqTester (single station) for the bq20z95. bqTester V1.02 available from TI program suite doesn't work and if using v1.02 to program the golden image ROM, the bq20z95 will get into a state which can no longer be recognized by the bq EVSW.

    Please, help!  

  • in reply to ming cheung
    Prodigy 50 points

    Hi Everyone,

    The Li-ion cells chemistry I use is convered by the TI's bq20z95_1_50a.senc, without the correct version of bqTester  (v1.06?) available from TI program suite, seems the only available s/w is the bq EVSW.

    I use the following flow to program a small lot of bq20z95, could anyone advice if this is ok, please:

    (1) Use bqEVSW to program the bq20z95 with bq20z95_1_50a.senc   

    (2) Use the bqEVSW to Import and WriteAll an golden .gg (static dataflash + pre-learned + pack specific data - SN)

    (3) Use the bqEVSW to perform PCB calibration (voltage, current etc)

    (5) Connect real batteries and enable IT using the bq EVSW

    (6) Seal the pack using bqEVSW

    Is there any risk I should be awared of using the bqEVSW or running a small production lot of bq20z95 using the bqEVSW ? Please, advice!

    Many Thanks,

    Ming 

  • in reply to ming cheung
    TI__Expert 6470 points

    Hi Ming,

    The bqTester and bqMTester will definitely support the bq20z95. That device i functionally the same as the bq20z90 + bq29330. It may be necessary to add a new device in the config file as described in the manual.

    Your method is OK at least for the standard LiCoO2 chemistry. If you have a different chemistry, then make a new .senc file by only programming chemistry in bqEasy, then saving the new .senc file using the PRO screen. But the question is why you have to program the .senc at all? You shouldn't need to upgrade to Ver 150a because we never released a  version prior to that.

    Its probably easier to use bqEasy EXACTLY in sequence to produce a golden image file. Then, you could use the first tab on bqEasy to quickly program your golden file (.DFI) into each production unit, instead of the more time consuming steps you describe in (1) and (2) above.

    Rgds,

    -dw