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BQ78350-R1A: BQ78350-R1A

Part Number: BQ78350-R1A
Other Parts Discussed in Thread: BQ78350, BQSTUDIO

Hello we use the BQ78350-R1A in combination with the BQ7693000DBT in a 6S setup.

software used bq78350_R1_v1_04_build_26.srec

The system was working uptil now we have found a strange behavior and in my opinion not a good one.

During charging there was one cell not in balance to high  normaly the balancing circuit will reduce this issue and the battery pack is in balance.

now the is one cell going in over voltage during charging and the SOV bit in BQstudio is going on. charging is not possible any more. now we start pulling current out of the battery un till the voltage is below the SOV and a certain treshold. at tha tpoint you would expect that the SOV will disapeare and that it should be possible to charge again. But the SOV stay active and the charge FET stay off . charging is not possible.

If we now look at the bottem side at SUV and try a silmilar test but at the low side then this meganism is working. we discharged the battery jus below the SUV level and the SUV bit turned on and discharge FET opend discharging stoped. The cell revoverd it self after a dome time and the level was above SUV and the threshold level for SUV. at that moment the SUV Bit turned of an discharge FET was active again. at the same time the SUV bit toggled to green in BQstudio also SOV bit toggled to green.this last behavior is strange only when cell is completly down the SOV alarm disapear. is there somting going wrong in the software of the BQ78350-R1A?

Kind regards

Rens

  • Hi Rens,

    Can you send your data flash settings (click Export on the BQStudio Data Memory screen)? Also, it would be great if you could collect a log file of this behavior - this would allow us to see the state of all of the voltages and status bits during the behavior observed. You can collect this by clicking 'Start Log' in the Register screen of BQStudio.

    Best regards,

    Matt

  • LOG file.rar

    • Log file include going to COV, after this discharge way under 4080mV,
    • Setting file from a 6S1P accu pack.

     

    Zie bijlage, alles ingepakt met Winrar i.v.m. Spam filters

     

  • Hi Rens, 

    Thanks for sending your data flash settings and log file. This clears up some confusion.

    The log file shows that you are observing a COV protection trigger. Your message says you see SOV triggered. SOV and SUV are different. These are Permanent Fails and behave differently from normal protections. Your settings show that you do not have Permanent Fails enabled, so it makes more sense that the log file shows COV.

    Normally, COV will recover when the cell voltages fall below the COV Recovery voltage. For your settings, this is 4080mV. However, if you read Section 3.3 of the Technical Reference Manual, there is another condition that can be required for recovery. Your data flash settings happen to be configured to require this additional condition. You have Protection Configuration:VAUXR set to 1 (default is 0) which also requires that the VAUX voltage also needs to fall below the Charger Present Threshold Voltage (you have this set to 3000mV in your settings). This explains the behavior you are seeing.

    Best regards,

    Matt

  • Hello Matt,

    Thanks for you clear explenation we have checked it and chaged the Chage present threshold.

    Kind regards

    Rens