• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 64 subscribers
  • Views 508 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

OCV value read

Pierre Le Gargasson
Intellectual 260 points
Other Parts Discussed in Thread: BQ27520-G4, BQ27520EVM, BQ27510-G3

Hi,

I'm testing bq27520G3EVM learning cycle with bqEASY. At the end of charge, FC bit is set. During relax, VOK is cleared but App Status never change to 01. Slua544 "Generate Golden Image" shows that the gauge take an OCV1 measure before Enable IT.

1) When OCV1 measure is taken ? In bqEASY step 5.1 by clicking Dsg/Wait Done or 5.2 Initialize IT ?

2) Where can I check if OCV1 measure happens ? (RAM, Flash ?)

3) After automated discharge to 3V at C/5 and relax 5h, battery voltage reach 3,43V. Is it too high to enable IT ? (Chem ID = 0162)

4) After charging, VOK is cleared during relax (30 min). Does App Status should update to 01 at this changing state or it will be updated after 2h relax ?

Thanks for help.

Pierre

  • 0
    TI__Genius 14985 points

    Hi Pierre,

    I recommend you do not use bqEASY for bq27520-G4.  You can run the learning cycle manually using GaugeStudio.

    OCV1 will be taken when you enable IT using the IT_ENABLE command, but don't send it until after waiting at least 5 hours once you reach empty.  You will see the RUP_DIS bit clear and the VOK bit set.

    3.43V is probably okay, but you could discharge using a lower current just to be safe.

    When VOK is cleared during relax after charge, Update Status (not App Status) should change from 00 to 01 and the Qmax in your dataflash should also be updated. 

  • 0 in reply to dMax
    Intellectual 260 points

    Hello dMax,

    Thanks for reply. I now use GaugeStudio 1.3.12 with bq24520-G4 firmware. I tried three learning cycles but failed at the same point (end of charge FC set, relax, VOK cleared but Update Status still 00).

    1 - I see differences between bqEASY and GaugeStudio. Before starting learning cycle in GaugeStudio, I manually reset "IT Enable" to 00 in DataMemory plugin. When I start automated learning cycle, IT Enable and QEN are set at the beginning of the first discharge. In bqEASY, they are set before charge. Is it OK ?

    2 - In calibration plugin, the bq27520EVM user's guide SLUU426A says, about Board Offset,

    "Remove load and short PACK– to LOAD–. Press the CC Board Offset Calibration button."

    Currently, I connect "battery -" to "load -" for Board Offset calibration only. Do I have to do the same for Coulomb Counter Offset ?

    Thanks,

    Pierre

  • 0 in reply to Pierre Le Gargasson
    Intellectual 260 points

    The bq27520 gauge is dead... Maybe due to 3,4 charging amperes. EVM max amp is 2A.

    Now trying Learning cycle with bq27510-G3 EVM. I reduced charging current to 1,7A. Status update still locked to 00. After charge, I continued with discharge. Logs reveals incorrect resistance values (Res. Scale). After going to negative, RUP_DIS sets. I also don't understand why Internal Temp falls and stay from 20°C to 8°C after 20s discharging. External Temp is always 20°C.

    I found this quote on the forum :

    "(f) When you discharge, the Resistance Table may update for a while, and then stop.  When this happens, RUP_DIS is set.  This generally indicates that your Chemistry ID choice is incorrect.  This means that the gauge has measured a resistance value that just doesn't make sense (i.e. is negative).  If you re-run your chemistry cycling or contact us, we will help you get a correct value."

    My battery is a SAFT MP176065 which is referenced in Chemistry list with Chem ID = 0162. So I never paid attention to this point. I currently do Chemistry Select Cycling to verify.