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BQ40z60 EVM - wakes up then sleeps in 30 seconds

Chintan Pathak4
Intellectual 845 points
Other Parts Discussed in Thread: BQSTUDIO, EV2400, BQ40Z60

Dear Forum, 

We recently got a BQ40z60EVM - 578, which is a charger and gauge board for use with Li-ion batteries with 2s-4s configuration. 

I am trying to test using 2 cells in series. As instructed in the User's guide, I connected the negative of cell 1 to 1N, then positive of cell 1 and negative of cell 2 on 1P, and positive of cell 2 to 2P, and two resistors of 1KOhm between 2P-3P and 3P-4P. 

Now, I connect a load of about 200 Ohms between the VSYS and PGND (I tried with a 10KOhm resistor as well), and a Power Supply between VAC and PGND, with voltage set to about 10.8 V, which is higher than the final charge voltage of two cells combined (4.2V + 4.2V).

Then I connect a EV2400 adapter using the SMBUS port, to a PC with bqStudio installed. When I launch bqStudio, I have to press the Wake-up button for bqStudio to recognise the gauge. Once it does, it is able to measure the voltage of the combined system which sits right now at about 7.3V (gauge reports 7267 mV). But gauge doesnt report any charge / discharge current nor does it report SOC etc. 

Also, the gauge goes to a sleep mode, in about 30 seconds. When I try to wake it up again by pressing the wake-up button, it wakes up for 30 seconds, and then sleeps again. In the sleep mode none of the registers update and I cannot communicate with the gauge. 

I learned that the BQ40z60 is pre-set for a 3 cell configuration and the "Settings" -> "Configuration" -> "DA Configuration" needs the values of CC0 and CC1, which I try to set using bqStudio and it gives an error called "operation failed because initial read of all data flash failed". I also tried unsealing the gauge, it required a code, which seemed correct in the textbox - 36720414 and FFFFFFFF for unsealing with full access, but these commands also, didnt work. 

My jumper settings are as follows: 

SERIES CELL SELECT (J4) - 2S

J2 - SYSPRES and ALERT

J7 - SYSPRES (in place)

I tried to use the LED DISPLAY functionality, but that didnt work as well. 

Am I missing some startup step ? Any guidance in this regards would be appreciated. 

Thanks and Regards

Chintan Pathak 

Research Scholar, 

University of Washington

  • 0
    TI__Guru 73830 points
    You are correct that the default configuration is 3S. You should be able to leave the cells off and apply 12V from VSYS to PGND. You can then read the DF and change the number of series cells to 2S. (You cannot work with a 3S configured gauge that only has two cells attached.) You can now remove the 12V and apply the cells. You need to short 2P to 3P to 4P, instead of using 1 kohm resistors.

    If you have sealed the pack, then I would reloaded the default srec file before reconfiguring the number of series cells. Otherwise, the gauge will reseal when reset and it makes it difficult to use.
  • 0 in reply to ThomasCosby
    Prodigy 130 points

    Hi Thomas,

    I have a similar question.

    What you mention about applied 12V on VSYS.....

    Which document has this instruction? I can't find it in TRM.

    I am a beginner for battery management design.

    Is there any design SOP for this?

    I see so many setting field in bqstudio.

    Can I have a simple start-up setting for 2S battery?

    And let the EVM can charge/discharge automatically.

    Sorry for many questions.

    I am very appreciated to get your advice to let our product successful.

    Mark 

  • 0 in reply to Mark Huang44
    TI__Guru 73830 points
    Mark,
    This is not covered in the documents, so I should clarify it in the EVM User's Guide. The problem is that the default setup is 3S, so a 3S voltage range has to be applied until the gauge can be converted over to 2S. You should be able to use the rest of the User's Guide to configure the data flash to support 2S. Most parameters are configured at a cell level, so you will not have to change many. (see the Charger parameters on page 13 and you will need to change the Term Voltage)
    Tom
  • 0 in reply to ThomasCosby
    Prodigy 130 points

    Hi Tom,

    Thanks for your reply.
    After I set DA configuration CC[1] and CC[0] to <01>, the EVM can work with 2S battery only.
    But it still can't charge/discharge automatically.
    However we meet other big problems.

    1. charger voltage setting
    When we set J4 to 2S and DA configuration to 2S, charger voltage is around 5.7V
    When we set J4 to 3S and DA configuration to 2S, charger voltage is around 8.5V
    I think 8.5V is a correct value for 2S battery. But why J4 needs to set as 3S?
    BTW we didn't connect any battery on J3.

    2. VSYS output power with AC only
    Anyway we use above 8.5V setting and connect electrical load on J5.(VSYS)
    And then we turn on 3W loading. The output(VSYS) turns off immediately.
    If we turn on 1W loading only, the output can work normally.
    We don't believe the EVM can only provide 1W to system load.
    BTW we didn't connect any battery on J3.
    PS. We can test this for 20W with battery only.

    Attached is our setting file.

    Thanks a lot for your support.
    Mark

    AC_UVP.zip

  • 0 in reply to Mark Huang44
    Prodigy 130 points
    The most important thing still is this.....

    It can't charge/discharge automatically.

    Is there a register to enable it?
  • 0 in reply to Mark Huang44
    TI__Guru 73830 points

    Mark,

    I am sorry for the delayed response, but I have been away from the forum for a few days. I have not had a chance to load your srec file to check the parameter setup, but I do know that you will need to attach cells to the J3 connector for the gauge / charger to work properly. The EVM User's Guide provides guidance on the cell attachments for a 2S configuration. You can try this to see if it helps.

    Tom