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BQ34z110 optimization cycle Step 5 VOK always set

Jannik Strakeljahn
Prodigy 80 points


Hi,
after discharging a 24V 7Ah batterysystem at 700mA till the voltage reaches about 20V (Step 4/5) i relaxed the Batteries (0mA, Voltage increases up to 21V) and the CCA flag was set for a short time. But VOK and QEN are always set? Any idea why the VOK flag isn´t cleared? Could it be described in step 2 that the Cell BL Set Volt Threshold wasn´t low enough?

Which parameters are depending on the VOK flag?

The "Update Status" is alwas 0x04.


Thanks,

Jannik

  • 0
    TI__Guru 73830 points

    Jannik,

    Do you have a log file and gg file that you can share? You will need to allow the pack to rest until the OCVTAKEN flag is set and the VOK flag should clear at that point.

    Tom

  • 0 in reply to ThomasCosby
    Prodigy 80 points

    Hi Tom,


    attached the two Files. The Datasheet says when ocv measurement is performed OCVTAKEN will be set to 1. OCV is always taken in relax mode? Are they any other requirements for going into relax as the parameters called "Current Threholds" like Dsg/Chg Current Threshold Dsg/Chg Relax Time?


    Jannik
  • 0 in reply to Jannik Strakeljahn
    TI__Guru 73830 points

    Jannik,

    The pack has not rested long enough in the log data. The OCVTAKEN flag did not set and the VOK flag did not clear. It did enter the rest state. You can see this from the Sleep bit getting set.


    Tom

  • 0 in reply to ThomasCosby
    Prodigy 80 points

    Hi Tom,


    thanks for your reply. After resting the batterypack last weekend the OCVTAKE flag was set, VOK was cleared and Update Status was set to 5.

    Now, after i did step 6,7,8 and 9 there is the following problem. During step 9, after relaxing the batteries the OCVTAKEN flag was set and VOK was cleared BUT the update status remains on 5. I red a little bit in the forum and found this theme: http://e2e.ti.com/support/power_management/battery_management/f/180/p/274169/958152.aspx#958152 . I checked my Avg I Last Run ant this was -683mA. C/10 in my case should be 700mA. Can this be the problem?

    After charging again and discharging to repeat the procedure from step 6. The VOK Flag ist not set when the battery is full charged and relaxed. So i don´t know if i can discharge the battery to become at least a update status "6".  What should i do now ? Repeat the whole procedure beginning at step 1? Send a TI-Endable to set VOK?

    All of this takes a long time (days) to repeat. So i´m interested in a quick solution without starting from step 1 if possible.

    Attached the gg file and the log. 0268.lc12v7ahstep9.rar

    Jannik

  • 0 in reply to Jannik Strakeljahn
    TI__Guru 73830 points

    Jannik,

    I checked you log and gg files. The Ra table did update during the discharge, but the pack transitioned directly from discharge to charge at the end of discharge. The pack did not have a chance to rest, so Update Status did not change. I think that you are fully charged now. Verify that OCVTAKEN is set and then discharge the pack again. Let it rest after discharge and Update Status should change to 06.


    Tom

  • 0 in reply to ThomasCosby
    Prodigy 80 points

    I think that you are fully charged now. Verify that OCVTAKEN is set and then discharge the pack again. Let it rest after discharge and Update Status should change to 06.

    When the batteries are discharged and relaxed a few hours OCVTAKEN is set. Over night i charged the batteries. Now, in the morgning the batteries are full charged but OCVTAKEN is cleared. Why?

    When i´ll try a discharge again it won´t take affect the Update Status to be 6 i think. Am i right?


    Jannik

  • 0 in reply to Jannik Strakeljahn
    TI__Guru 73830 points

    Jannik,

    Has the pack rested long enough for OCVTAKEN to set? Is VOK still set? If you discharge without the rest flags set properly, then a QMAX update will not occur. The device may still update the Ra-table and set Update Status to 06.

    Tom