BQ28Z610: Help needed creating a golden image for 2s Panasonic NCR18650BF - FC never sets

Hi Salvo,

I tried replying directly to you, but it failed to send.

I did, after many attempts, manage to produce a GI, but not without problems. I ended up with a capacity of about 5000mAh, which was as least enough to carry on with our board development. Now we have a pre-release board I am going to have to try again.

It does seem to be a process that needs a fair amount of luck as well as judgement !

I have been building up my own notes of the process and I am attaching them here - I hope that they may help you.

Kind regards,

Andy



Learning cycle for flash-based Impedance Track gas gauge BQ27510-G3

Equipment:

bq27510EVM
Battery
VARTA EasyPack L 56446 3.7v 1200mAh
VARTA EasyPack XL 56446 3.7v 2400mAh
FEY PA-UL-LNB46.R001 3.6v 6700mAh
EV2300 (or EV2400)
bqStudio 1.3.54.1 (1.3.86.3 errors on Parameter Q&A save)
2 x DMM (voltage & current)
PSU capable of 3000mA (or max charge for battery)
Discharge resistors

Initialise

Program the vanilla, default image into the 27510. Reset.

Chemistry

Program the correct chemistry ID with the TI bqStudio Chemistry Tab plug-in. (If required to determine the chemistry ID, use the online GPC tool.) Use the single cell version of the VARTA in Chemistry.

Configure the basic parameters

Using bqStudio’s Parameter Q&A tab, set design capacity, design voltage, terminate voltage, design energy, and taper current or taper rate to values that correspond to the battery and system specifications.

CC Offset Calibration

This performs the internal calibration of the coulomb counter input offset.

Check just the Calibrate CC Offset box
Press the Calibrate Gas Gauge button
Board Offset Calibration

This performs the offset calibration for the current offset of the board. It is expected that no current is flowing through the sense resistor while performing this calibration step.

Remove load and short Pack– to GND
Check just the Calibrate Board Offset box
Press the Calibrate Gas Gauge button
Temperature Calibration (optional)

Measure the temperature for PACK
Type the temperature value into Applied Temperature
Select if the temperature sensor to calibrate is the internal or external
Check just the Calibrate Temperature box
Press the Calibrate Gas Gauge button




Pack Current Calibration

Connect a load to LOAD– and LOAD+ that draws approximately 1 A, or
Connect a current source to LOAD– and Pack-
Measure the current and type value in mA into Applied Current using (-) for current discharge
Check just the Calibrate Current box
Press the Calibrate Gas Gauge button
Voltage Calibration

Measure the voltage across Pack+ and Pack– with a calibrated meter
Type the voltage value in mV into Applied Voltage
Check just the Calibrate Voltage box
Press the Calibrate Gas Gauge button
Send a RESET command (0x0041) via the bqStudio command bar.

Set register log running (optional).

The battery should now be discharged to empty (terminate voltage) at about C/5 (For EPXL I actually used 8 Ω, which is ~= C/4.9). You should then allow the battery to relax for at least five hours after reaching terminate voltage.

After at least five hours have elapsed, check the Control Status register in bqStudio to make sure that the RUP_DIS bit is cleared, the VOK bit clear and that the update status is 0x00.

Send an IT_ENABLE command (0x0021) via the bqStudio command bar. QEN should set.

( UNSEAL and UNSEAL_FULL_ACCESS via the bqStudio command bar if needed – probably not. )

Begin charging the battery at C/2 rate (or max rate). VOK should set.

Once the battery is charged to full (taper current) and the FC bit is set, a relaxation of at least two hours is required. After at least two hours have elapsed, the update status in data flash should be 0x01. If it isn't, it means something must have caused learning to fail.

Discharge the battery at a rate higher than C/10 but less than C/5 until empty (terminate voltage).

Relax the battery for at least five more hours.

At the end of this process Qmax and Resistance Tables should have been updated and your update status in data flash should be 0x02. if it isn't, it means something must have caused learning to fail.

Once learning is complete, change cycle count in data flash to 00, Write Ra Table, Qmax, Cycle Count and Update Status to gauge, followed by a RESET command (0x0041), then extract an srec, bqfs and dffs files using bqstudio. These will be your golden files which you will flash on multiple devices. The srec and bqfs contain the instruction flash and data flash parameters while dffs only contains data flash parameters.

It is recommended to use the bqStudio Data Memory plug-in to export a gg.csv file both before and after the learning cycle to compare Qmax and Ra table values. After a successful learning cycle, Qmax should be 5-10% higher than design capacity and Ra tables should have changed from the beginning of the learning cycle. Also recommended is running another charge/relax/discharge cycle in order to analyse the gas gauge’s state-of-charge accuracy.





See also

Achieving The Successful Learning Cycle (slua597)

How to Generate Golden Image for Single-Cell Impedance Track™ Devices (slua544)

bq27510EVM System-Side, Single-Cell Impedance Track™ Technology Evaluation Module (sluu327b)

Hi Andy,

thank you very much for your very detailed informations.

At the end of your Learning Cycle the Relative state of charge was enabled?

I have seen that you used my same battery FEY PA-UL-LNB46.R001 3.6v 6700mAh.

Please, can you send me your gg.csv file to use as example for my fuel gauge bq28z610?

Thank you in advance for your support,


Salvo