BQ40Z50: Over voltage analysis

Hello Frank,

This seems to be a charger issue, the gauge cannot supply a voltage to the battery in this way.

Can you explain the system more and the testing done? Can you share a log captured using bqStudio and EV2400?

Sincerely,

Wyatt Keller

Hi Wyatt,

Thank you.

Please find the log file got from the BQStudio.
It is not logged at the same time what the ripple of the post above.

battery charge log_Marked.xlsx

Battery charger is designed using bq24707a to log battery charge.
For sample 596,

I think that there is data indicating that an abnormal voltage has occurred.

VCC DC 24V power supply to bq24707A,

The peripheral design of bq24707a follows the Typical System Schematic.

It is necessary to investigate the cause of the high voltage for bq24707A,
I don't know what kind of approach to do, and I appreicate your valuable suggestions.

First, I want to know the reason is hardware design problems or software or communication anomalies.

The ripple in the post above.

Ch1: SMBus SCL
CH3: voltage between Battery + and -
CH4 battery charging current

Thanks.

Hello Frank,

Is the charger also on the same SMBus line? Do you know what IC caused the SCL line to oscillate like that?

As I mentioned before the gauge can't supply a voltage to the battery or current, so there may be an issue with the charger. I would make a separate post linking that charger so the charger team can also take a look at this.

Sincerely,

Wyatt Keller

Hi Wyatt,

Thank you.

waiting you share me the thread link.

Regards,

Hello Frank,

Sorry I believe there may be a misunderstanding, you should be able to make a separate thread to discuss with the charger team as well.

Sincerely,

Wyatt Keller

Hi Wyatt,

Thank you.
Battery charger (bq24707a) and Battery fuel gauges (bq40z50r3) exist on the same SMBus line.
Communication seems to have not been done at the time the overvoltage occurs.
Please find the attached pictures.

[the time of overvoltage ripple]

[voltage oscillates on the SCL line]

The SCL line oscillates for about 40 seconds,
I do not know the cause to become 5V again afterwards.

I have added pictures, please confirm.
Fully oscillate.
The SCL line has been pulled up to 5V via 4.7K ohms on the charger side!
(Unfortunately, I did not measure the SDA line. )

After this test, fuse opened as the battery pack self protection
Battery charger is not damaged and can charge other batteries.

If it is not Battery fuel gauges issue, can you help you to create a case to analyze whether the Battery charger issue.

Thank you for your valuable suggestions.

Regards,