BQ34Z651: Charging being prevented at high SOC

David Wright33

Part Number: BQ34Z651

Hi There,

I am having an issue whereby charging is being prevented when I reach a high SOC (>95%). The result of this is that it is impossible for me to fully charge by battery. I have verified (both in the registers and on the PCB) that the CHG FET is being turned off but I don't seem to be able to figure out why.

No faults are being triggered and I cannot find an explanation for this in the Literature so I don't know what to change to stop this happening.

I have attached my ROM file for reference:

/cfs-file/__key/communityserver-discussions-components-files/196/1145.651_5F00_4cell_5F00_HG2_5F00_v3.zip

Thanks,

David

over 7 years ago

0 WM5295 over 7 years ago

TI__Guru 54715 points

Hi David,
Thanks for the file. What is the setup condition for the event: does the FET turn off on every cycle or only after certain operation? Is there a log file showing the behavior?

0 David Wright33 over 7 years ago in reply to WM5295

Intellectual 805 points

Hi There,

Here is the log file that I just generated. This happens every cycle, there doesn't seem to be a defined event that causes it.

/cfs-file/__key/communityserver-discussions-components-files/196/5657.062618_5F00_full-charge-test.log

0 WM5295 over 7 years ago in reply to David Wright33

TI__Guru 54715 points

Hi David,
The log shows you are logging perhaps 8 times per second. The gauge only updates values once per second. Spending time on high priority communication likely prevents the gauge from operating properly. 4 seconds is the default. Slow the log time to less frequently than 1 per second.

0 David Wright33 over 7 years ago in reply to WM5295

Intellectual 805 points

Hi There,

I have slowed the logging to once every 2 seconds so that should prevent that being an issue. This however did not change the outcome. Attached is a new log.

/cfs-file/__key/communityserver-discussions-components-files/196/2112.062618_5F00_full-charge-test-2.log

0 WM5295 over 7 years ago in reply to David Wright33

TI__Guru 54715 points

Hi David,
In your slower log:
The battery is charging.
When RSOC reaches 96% TCA is set in BatteryStatus
The charge FET turns off since Operation CfgB [CHGFET] (bit 5) is set. So that stops the current.
I don't see why TCA clears since TCA Clear % = 95 and RSOC does not drop in the log, or why the charge FET stays off when TCA clears. There is probably some other setting influencing this. Is this a new configuration or one unit of an existing configuration which does not work like the others?

Power management

Power management forum

BQ34Z651: Charging being prevented at high SOC