BQ40Z60: VCT never set

Allard Potma

Part Number: BQ40Z60

I've attached a log file of a charging sequence (last part). Can someone tell me why the VCT flag is never set? The FC flag is also not set, but I think this is related to the VCT flag.

Relevant flash settings:

Charging voltage: 4200mV (3S4P pack so total 12600mV)

Charge term taper current : 15mA

Charge term voltage: 75mV

I think that both of these are reached?

SOC Flag Config A = 0x0C88

SOC Flag Config B = 0x8C

SBS Gauging Configuration[RSOCL] = 1 , in the log file the RSOC reaches 100% this means that VCT does happen?

2.log.zip

over 7 years ago

0 bdefar over 7 years ago

TI__Prodigy 680 points

Hi Allard,
One of our BMS experts has been assigned to your issue and will answer shortly.

0 Jasper Yi over 7 years ago in reply to bdefar

TI__Intellectual 1365 points

Hi Allard,
BatteryStatus() = C0 which means that [DSG] bit is set when RSOC is 100%. DSG bit should be "0" in order to set [VCT] bit.
When RSOC is 100%, AverageCurrent() is 10mA according to your log file. What is your Quit Current threshold in your DF ?
If it is equal to or greater than 10mA, it meets the relax condition and DSG bit is set to "1".

0 Allard Potma over 7 years ago in reply to Jasper Yi

Prodigy 90 points

The Quit current Threshold is indeed set to 10mA, what do you recommend, looking at my log file? Should I decrease the value?

Thanks.

0 Jasper Yi over 7 years ago in reply to Allard Potma

TI__Intellectual 1365 points

I would like to recomend to increase "Charge Term Taper Current" value higer than 15mA.

VCT requires two consecutive 40-s periods when AverageCurrent() < Charge Term Taper current. If it is close to Quit Current threshold(10mA), it enters Relax mode before meeting the timing condition. Low Termination current doesn't help to increase the capacity but affected the charging time significantly.

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BQ40Z60: VCT never set