BQ34Z100-G1 resets it's values in rest mode

Shlomy Sasson

Other Parts Discussed in Thread: BQ34Z100-G1, BQ34Z100EVM

Hello,

I have a problem with the Gas gauge BQ34Z100-G1 while working with Pba EFB 70Ah battery (Varta E45):
while leaving the battery for rest the BQ34Z100-G1 resets its values and think that the battery SOC is 100%,
For example: The battery was 100%, I discharged it to 66%, I did let the battery rest and after about 40 minuts the gauge reseted its FCC,True RC and SOC value.
The log for the test is attached here, can anyone please help me understand whats causes the gauge to resets it's values?
It happens in sample number 5762.

2654.afterOCVwhileDischarging.log

Regards,
Shlomy

over 8 years ago

0 ThomasCosby over 8 years ago

TI__Guru 73830 points

This looks like a ChemID problem. Can you export an srec file from the pack and attach it to this e2e post?

0 Shlomy Sasson over 8 years ago in reply to ThomasCosby

Prodigy 90 points

Hi Tom,

Here is the .srec file.

0100_0_16-bq34z100G1.zip

0 ThomasCosby over 8 years ago in reply to Shlomy Sasson

TI__Guru 73830 points

Shlomy

You have not run the optimization cycle to update Qmax and the Ra table, so gauging will not be accurate. You can use this procedure to run the optimization cycle.

Tom

0 Shlomy Sasson over 8 years ago in reply to ThomasCosby

Prodigy 90 points

Tom

Thanks for your answer.
I'm about to run the optimization cycle in according to your instructions, I just have a small query:
Since I'm using the BQ34Z100EVM with BQ34Z100-G1 chip on it the thermistor is soldered to the board, sould I disconnect the thermistor from the boards and connect and extention cables from the board to the thermistor, and then attach the thermistor to the battery with glue or adhecive tape?
Or is it enough just to put the EVM close to batter?

Regards,
Shlomy

0 ThomasCosby over 8 years ago in reply to Shlomy Sasson

TI__Guru 73830 points

It would better to attach the thermistor to the cells, but my experience has been that you will damage the thermistor trying to remove it from the PCB. You can leave it attached to the board for the optimization cycle. The discharge currents are not large enough to cause much heating in the cell.

0 Shlomy Sasson over 8 years ago in reply to ThomasCosby

Prodigy 90 points

OK thanks, I'll run the learning cycle as you advised.

I have one more question: At the steps of the learning cycle step 3 says "Charge the pack to charge termination"
and step 7 says "Fully charge the pack to charge termination".

I'm trying to understand what is "Charge termination means"
My battery nominal voltage is 12v, and my upper voltage limmit I want to use for my application is 14.8v and the lower voltage limit I want to use is 10.5v.
Is that mean the my charge termination is 14.8v and my discharge termination is 10.5v?

0 ThomasCosby over 8 years ago in reply to Shlomy Sasson

TI__Guru 73830 points

The Charge Termination criteria are discussed on page 37 of the datasheet.

Power management

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BQ34Z100-G1 resets it's values in rest mode