BQ40Z50: BQ40Z50R1 not going Shutdown mode

Hi Max,

Based on the log file, it seems like there are random pulses of voltage larger than Vstartup on the PACK pin. If you send the gauge into shutdown and this voltage on the PACK pin is observed, then it will exit shutdown. Is there anything connected to the pack connection at this time?

Regards,

Anthony

Hi

No we have not connected any load on the battery pack.

Also If we have the NR =1 ,does it impact the Shutdown on the battery pack.

Also in shutdown condition it is given as follows

If any cell voltage reaches the shutdown voltage or all the 4 cells to reach the shutdown voltage and it should be less than charge present threshold to reach the shutdown mode.

Why because when one cell reaches the shutdown voltage it goes to shutdown mode and it is exiting from mode for 10 to 15 times and after that it reaches the shutdown mode.,

Regards

MAX

Hi Max,

The NR bit should not change how the gauge enters shutdown. If any cell voltage reaches the Shutdown Voltage, it will start to enter shutdown, however it will not until the delay has passed and the voltage at the pack pin is less than Charger Present Threshold. I believe it keeps exiting due to the voltage at the pack pin been seen, which can be seen in the log above.

Regards,

Anthony

Hi

What can be done to do the battery pack to enter into shutdown mode.

Also If it does not enter the shut down mode and battery pack is deep discharged it can be come back to normal operating by precharhing (Enabling Precharge command) right?

Regards

MAX

Hi Max,

In the log file, it seems like the PACK is receiving the voltage causing wake up due to the FETs being active and allowing voltage to pass to PACK. However, this should only be available if the current has crossed the CHG Current Threshold or DSG Current Threshold. Can you please share the .gg file of the gauge settings?

Also, yes the precharging capability would allow the cell to recharge from a deeply discharged state.

Regards,
Anthony

Hi

Attached the ,gg file for your reference.

When we discharged the battery under 500mA,It does not got terminated and battery pack failed.

Screen shot also attached

3666.gg.csv

Hi Max,

The system is most likely moving in and out of shutdown mode at this point. The SDV bit is set signifying that the voltage is less than the Shutdown Voltage parameter, and the Voltage at the PACK pin (4799mV in screenshot above) is less than the Charger Present Threshold (13000mV in gg file) which would allow it to enter shutdown, but the Voltage at the PACK pin is still greater than Vstartup (~2.2V) which would cause it to exit. This cycle of the gauge observing these measurements is causing a cycle of entering and exiting shutdown. 

Regards,

Anthony

Hi Anthony

Then How can we rectify this ,and put the battery under shutdown mode.

Since we are using in our equipment's, Need to ensure that the packs are in shutdown mode once the voltage has been reached.

Hi Max,

There is something in the system currently causing the Voltage at the PACK pin to observe 4799mV. If there is nothing connected to PACK at this time, and if the actual measured voltage at the PACK pin is 0, please try calibrating the PACK pin voltage in bqStudio:

If this voltage is 0, then the device will be able to enter shutdown.

Regards,

Anthony

Hi

Understood ,So i have put shutdown voltage as 3150,and Threshold voltage as 13000mV.

So when this voltage is reached automatically Shutdown will be triggered right? Also PCHG_CMM (precharge command )has  been enabled so once the voltage reaches less than 2.2V/cell, automatically it will be charged right?

5751.gg.csv

Kindly go through the csv file and kindly ensure whether battery pack are in safe operating zone.

Hi Max,

Below is the conditions for the device to enter shutdown, where the minimum cell voltage must be less than the Shutdown Voltage, along with the voltage at the PACK pin being less than the Charger Present Threshold. These two conditions must be met for the device to enter shutdown.

The voltage at the PACK pin will determine when the device exits shutdown, where this cannot be greater than Vstartup at this time.

Regards,

Anthony

 Hi

But why at some occurrence it is not going to shutdown mode. even the pack voltage is lesser than start up voltage at some batteries, 

Also when the battery is deep discharge and When the PCHG_CMM is enabled the pack will be charged right?

.

Hello Max,

Thanks for the update. We won't close the thread and we are reviewing your question.

Thank you,
Alan

Hi Max,

If possible, please share a log file of the gauge not entering shutdown when the PACK voltage is less than the startup voltage for us to review.

Yes, if the battery is deeply discharged, PCHG_CMM will allow for 0V charging:

Regards,

Anthony