BQ34Z100-G1: Accurary on pulse discharge

Serge Maloizel

Part Number: BQ34Z100-G1
Other Parts Discussed in Thread: BQ34Z100

We use a BQ34Z100-G1 on a 6S2P battery where the application drains pulse current from the battery.

To check the accuracy, we made tests at different current profil.

A first test with pulse at 8A for 0.3s and rest for 0.9s, the Bq report an average current at 2A and the SOC was OK during the discharge.

A second test with pulse at 7A for 1.3s and rest for 2.6s, the Bq report an average current between 1.1A and 1.7A instead 2.33A and the SOC drops suddendly from 34% to 0% before the end of discharge.

Attached zip with record files and .gg files

Pulse_discharge_bq34Z100.zip

Waiting for your explanation about this accuracy difference

Best regards

Serge Maloizel

over 8 years ago

0 Onyx Ahiakwo over 8 years ago

TI__Guru* 76230 points

Hi Serge,

Did you identify your chem id correctly and did you perform learning cycle on the IC?

thanks
Onyx

0 Serge Maloizel over 8 years ago in reply to Onyx Ahiakwo

Intellectual 390 points

Hi Onyx,

Yes we identify properly the chem ID and dir a learning cycle.

We found the reason of our problem: it is because on discharge at 7A/1.3s - 0A/2.6s, the bq goes in sleep mode during 0A 2.6s.

With discharge at 8A/0.3s - 0A/0.9s, the bq doesn't go in sleep mode during 0A 0.9s.

It seems there is no register "time to sleep" but only a register for "time to full sleep", am I right? But we don't want to put the bq in full sleep mode.

We just want the bq stay awake for some seconds when current is below sleep current.

Best regards

Serge

0 Onyx Ahiakwo over 8 years ago in reply to Serge Maloizel

TI__Guru* 76230 points

Hi Serge,
Try setting the SleepWakeCHG bit in pack configuration C register and rerun your test to see if that helps.

thanks
Onyx

0 Serge Maloizel over 8 years ago in reply to Onyx Ahiakwo

Intellectual 390 points

Hi Onyx,

Pack configuration C is : 37 so SleepWakeCHG is already set at 1.

in adta sheet, it is written: "SleepWakeCHG: Enable for faster sampling in SLEEP mode."

What is the sampling rate in SKEEP mode when bit is "0"?

What is the sampling rate in SLEEP mode when bit is "1"?

Best regards

Serge

0 Onyx Ahiakwo over 8 years ago in reply to Serge Maloizel

TI__Guru* 76230 points

the gauge takes measurements once every 20s in sleep. if that bit is set, it tries to account for missed current while in sleep mode if when it wakes it measures current above the sleep current threshold. The description in the document isn't very accurate.
thanks
Onyx

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BQ34Z100-G1: Accurary on pulse discharge