BQ27426EVM-738: Generating an error [VOK: Not Clear] during learning cycle

Sebastian Kopp

Intellectual 285 points

Part Number: BQ27426EVM-738
Other Parts Discussed in Thread: BQ27426, GPCCHEM,

Hey all,

during the manual learning cycle with BQ27426 an error [VOK: Not Clear] is generated.

Conditions:

Charge Setup: Notify when FC-Bit is set

Discharge Setup: Termination Voltage: 3200

Apart from Chem ID the default values wasn't changed.

I'm using the preinstalled chemistry version (1202) for a Li-Ion-Battery.

Procedure:

Until the second relaxation everything is working fine, but after relaxation the learning cycle is cancelled.

Error: [VOK: Not Clear]
Learning cycle cancelled

As attachment please find the log file.

Could you please help me?

Regards

Sebastian

29.4._learning cycle.log

over 5 years ago

0 Andy Liu (BMS) over 5 years ago

TI__Guru 52115 points

Hi Sebastian,

Could you also provide your gg file? Thanks.

Andy

0 Sebastian Kopp over 5 years ago in reply to Andy Liu (BMS)

Intellectual 285 points

Hi Andy,

have a look to attachment.

Regards

Sebastian

file.gg.csv

0 Andy Liu (BMS) over 5 years ago in reply to Sebastian Kopp

TI__Guru 52115 points

Hi Sebastian,

I see the Terminate Voltage voltage is set to 3200mV in your gg file. What's the actual term voltage of the battery cell you are using? Also, could you tell me which chemistry id you have used? Thanks.

Andy

0 Sebastian Kopp over 5 years ago in reply to Andy Liu (BMS)

Intellectual 285 points

Hi Andy,

according to the datasheet the termination voltage can be 3000mV.

The chemistry ID 1202 was used.

Sebastian

0 Andy Liu (BMS) over 5 years ago in reply to Sebastian Kopp

TI__Guru 52115 points

Hi Sebastian,

The chemistry id #1202 is for a battery that operates from 4.2V to 3.0V. When you do the learning cycle, you need to set the terminate voltage to the minimum voltage of the battery as specified in the manufacturer’s datasheet (3.0V). After the learning cycle is completed, this value can be adjusted upwards if there is a need for the gauge to report 0% at a higher voltage

Andy

0 Sebastian Kopp over 5 years ago in reply to Andy Liu (BMS)

Intellectual 285 points

Hi Andy,

i did a learning cycle with your suggestion (Termination Voltage: 3000 mV) again but the same failure was occured.

Please have a look to the files.

Regards

Sebastianfile_5.5.20.gg.csv log_5.5.20.log

0 Andy Liu (BMS) over 5 years ago in reply to Sebastian Kopp

TI__Guru 52115 points

Hi Sebastian,

I'm a bit concerned about chemistry id you are using now.

I would suggest you follow the instruction manual in the GPCCHEM tool (see the link below) and send all the required data to it. Share with me the GPC report once you receive it.

http://www.ti.com/tool/GPCCHEM

Andy

0 Sebastian Kopp over 5 years ago in reply to Andy Liu (BMS)

Intellectual 285 points

Hi Andy,

i did the GPCCHEM.

Please have a look to attachment.

Regards

Sebastian

5355.Data_7.05.20.zip 0257.Data_7.05.20-report.zip

0 Andy Liu (BMS) over 5 years ago in reply to Sebastian Kopp

TI__Guru 52115 points

I see you posted two threads on the same issue. I will close this thread and provide my feedback in the other thread.

0 Sebastian Kopp over 5 years ago in reply to Andy Liu (BMS)

Intellectual 285 points

Hi,

Andy, that's not entirely true.

This thread is about: Generating an error [VOK: Not Clear] during learning cycle regarding BQ27426EVM-738.

The other thread is about a problem from GPCChem, that was occuring during the characterisation of the battery that im using.

Or are the 2 problems directly related?

Regards

Sebastian

0 Kang Kang over 5 years ago in reply to Sebastian Kopp

TI__Mastermind 24870 points

I looked at the log file. The discharge current is very high. Can you switch to a lower discharge current such as C/5?

The relaxed voltage bounced up and I think the learning cycle failed probably due to RUP_DIS being set. Check the Flags() register.

I think by re-running at a lower rate, you should get a better learning cycle.

It could also be that the learning cycle failed due to a bad chemID match. Can you send us a GPCCHEM log file and we can determine if the chemID is a good match to your battery?

0 Sebastian Kopp over 5 years ago in reply to Kang Kang

Intellectual 285 points

Hi Kang,

please have a look to attachment.

At the moment im trying one more learning cycle. Keep you updated.

Regards

Sebastian5314.Data_7.05.20.zip 8484.Data_7.05.20-report.zip

0 Andy Liu (BMS) over 5 years ago in reply to Sebastian Kopp

TI__Guru 52115 points

Hi Sebastian,

The chemistry id is very critical for the learning cycle. Without a good chemistry id, the learning cycle will most likely fail.

As I mentioned in the other thread, there is something wrong with your GPC report. Bascially, the deviation is too high.

I would suggest you collect data for the GPCCHEM tool again and see if you can get a good matching id with a reasonable deviation.

Andy

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BQ27426EVM-738: Generating an error [VOK: Not Clear] during learning cycle