BQ34Z100-R2: GPCCHEMID Report

Fahad Akhtar

Part Number: BQ34Z100-R2
Other Parts Discussed in Thread: BQSTUDIO, BQ27426

I tried GPC Chem ID tool by logging the data using BQstudio. My cell is Li-ion (LFP) with 280Ah capacity

I am pasting the results of GPC report, do you see any concerns? Or should I just use the Chem ID 481 as suggested by the tool

Chemistry ID selection tool, rev=2.54

Configuration used in present fit:
ProcessingType = 2
NumCellSeries = 1
ElapsedTimeColumn=0
VoltageColumn = 1
CurrentColumn = 2
TemperatureColumn = 3

Best chemical ID : 481 Best chemical ID max. deviation, % : 26.23

Summary of all IDs with max. DOD deviation below 3%

Chem ID max DOD error, % Max R deviation, ratio
0 0 0

Accuracy Error: Deviation is so high that it is most likely due to anomaly in the data. Please check that data files have recomended format, units and test schedule

Selection of best generic ID for ROM based devices like bq274xx

Device / Family #1
Generic Chem ID Device/ Voltage/ Chemistry max DOD error, %
354 bq27411-G1C: 4.35V LiCoO2 32.13
3142 bq27421-G1D: 4.4V LiCoO2 38.92
128 bq27421-G1A: 4.2V LiCoO2 50.67
312 bq27421-G1B: 4.3V LiCoO2 99.07
Best generic ID 354
Warning: Generic ID Deviation is so high that it is most likely due to anomaly in the data. Please check that data files have recomended format, units and test schedule

Device / Family #2
Generic Chem ID Device/ Voltage/ Chemistry max DOD error, %
354 bq27621: (ALT_CHEM2) 4.35V LiCoO2 32.13
1202 bq27621: (default) 4.2V LiCoO2 32.21
1210 bq27621: (ALT_CHEM1) 4.3V LiCoO2 35.72
Best generic ID 354
Warning: Generic ID Deviation is so high that it is most likely due to anomaly in the data. Please check that data files have recomended format, units and test schedule

Device / Family #3
Generic Chem ID Device/ Voltage/ Chemistry max DOD error, %
3230 bq27426: (default) 4.35V LiCoO2 31.09
1202 bq27426: (ALT_CHEM1) 4.2V LiCoO2 32.21
3142 bq27426: (ALT-CHEM2) 4.4V LiCoO2 38.92
Best generic ID 3230
Warning: Generic ID Deviation is so high that it is most likely due to anomaly in the data. Please check that data files have recomended format, units and test schedule

10 months ago

0 Wyatt Keller 10 months ago

TI__Guru** 102285 points

Hello Fahad,

Please share the data submitted to the tool so we can review it.

Sincerely,

Wyatt Keller

0 Fahad Akhtar 10 months ago in reply to Wyatt Keller

Prodigy 210 points

WaapisChemIDTest.zip

Attached please find

0 Wyatt Keller 10 months ago in reply to Fahad Akhtar

TI__Guru** 102285 points

Hello Fahad,

It looks like the voltage drops suddenly near the end of discharge, do you know what is the cause for this? I would not expect there to be a voltage jump. Also the voltage is extremely stable for most of the discharge, is this an LFP type chemistry?

Sincerely,

Wyatt Keller

0 Fahad Akhtar 10 months ago in reply to Wyatt Keller

Prodigy 210 points

Yes this is LFP cell (280Ah). The load bank cuts off when cell voltage reaches 2.5V. The voltage drop is completely expected as current goes from 28A to zero. The voltage jumps down at the end of discharge and then relaxes overtime to a higher value, that's typical of Li cell

0 Wyatt Keller 10 months ago in reply to Fahad Akhtar

TI__Guru** 102285 points

Hello Fahad,

I was referring to the voltage drop right before, it looks like there are a couple steps there:

It may be best to do a cycle without the cutoff if possible, or stop the discharge before this occurs.

Sincerely,

Wyatt Keller

0 Fahad Akhtar 10 months ago in reply to Wyatt Keller

Prodigy 210 points

Wyatt

Can you please explain what do you mean without cutoff? Once battery is fully discharged (2.5V reached) we have to shut off the current. What is the alternative approach?

We will do another run but please note that you will still see these steps as this is typical of a Li cell. The first step is voltage increase due to charging. 2nd step is 5hr rest after charge, 3rd step is discharge and last step is 5hr rest after discharge. Please see Figure 1 of SLVA725A, it has similar sudden V drop at the end of discharge

Thanks

Fahad

0 Wyatt Keller 10 months ago in reply to Fahad Akhtar

TI__Guru** 102285 points

Hello Fahad,

Near the end of discharge there are multiple step functions before it drops off. We want this cutoff to be smooth as possible so the tool can see the voltage knee. For Li-ion cells there should be no direct step function near the end of discharge, it should be a smooth curve which we call the knee.

Sincerely,

Wyatt Keller

Power management

Power management forum

BQ34Z100-R2: GPCCHEMID Report