BQ34Z100-G1: AvrageTimeToFull: estimated time not accurate

Emmanuel Tillol

Prodigy 155 points

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

Hello,

I'm starting to use a bq34z100-g1 with a Nimh pack (Arts Energy Endurance L1 24V 10Ah).

Chem ID : 6113

My learning cycle seems ok (status = 6), but the gauge cannot estimate accurately the time to full.

Here are some charging cycles @ C/2 (constant current 5A) which should set the time to full to 2h (120min) at the start of the charging cycle. The gauge estimates 180min (~50% off). During the charging cycle, the ttf estimation changes abruptly (cf. graph)

1234.lc_arts_nimh_24V_10Ah.zip 376data_memory.gg.csv.zip

Maybe some parameter is wrong in my configuration? Please, tell me how to correct that.

(I attached the log file and the last auto exported .gg.csv for completeness)

over 6 years ago

0 Bryan Kahler over 6 years ago

TI__Mastermind 25955 points

Hi Emmanuel,

Thank you for the logs and information. I will provide an update by Tuesday.

Sincerely,
Bryan Kahler

0 Bryan Kahler over 6 years ago in reply to Bryan Kahler

TI__Mastermind 25955 points

Hi Emmanuel,

Please perform a discharge in excess of 600 seconds at the current you want to measure, fully charge the system and perform the accuracy test again. Please send the log of these results and let me know how it turns out.

Sincerely,
Bryan Kahler

0 Emmanuel Tillol over 6 years ago in reply to Bryan Kahler

Prodigy 155 points

Hi Bryan,

here are the results : discharge C/2 (5A) for about 1200s (20 min) and charge to full at the same C/2 rate (should be about 20 min time tu full). The estimated time is about twice as much.

6036.LOG.zip

1725auto_export.gg.csv.zip

(the log file starts with the learning cycle, the 20 min discharge followaed by the charge to full starts at 513585 seconds, elapsed time)

0 Batt over 6 years ago in reply to Emmanuel Tillol

TI__Mastermind 42535 points

Thanks for the logs. This is going to take some time to analyze. Please expect a reply by next Wed.

0 Bryan Kahler over 6 years ago in reply to Batt

TI__Mastermind 25955 points

Hi Emmanuel,

Thank you for the logs. We are still analyzing the data and will have an update by EOD Friday.

Sincerely,
Bryan Kahler

0 Bryan Kahler over 6 years ago in reply to Bryan Kahler

TI__Mastermind 25955 points

Hi Emmanuel,

After reviewing the logs and settings, please modify the charge efficiency parameters discussed in section 7.3.6.16 of the datasheet.

Tracking state-of-charge during the charge phase is relatively easy with chemistries such as Li-Ion where essentially none of the applied energy from the charger is lost to heat. However, lead-acid and NiMH chemistries may demonstrate significant losses to heat during charging. Therefore, to more accurately track state of charge and Time-to-Full during the charge phase, the bq34z100-G1 uses four charge-efficiency factors to compensate for charge acceptance. These factors are:

Charge Efficiency
Charge Eff Reduction Rate
Charge Effi Drop Off
Charge Eff Temperature Compensation.

Sincerely,
Bryan Kahler

0 Emmanuel Tillol over 6 years ago in reply to Bryan Kahler

Prodigy 155 points

Hi Bryan,
Thank you for your help.
Could you help me to set these parameters?
I found Pb Temp Comp and Pb Reduction Rate in bqstudio (24.960% and 10%, respectively which are the default values as I didn't change them)
but what are the other two parameters (I assume they are Charge Efficiency and Charge Effi Drop Off)?

0 Bryan Kahler over 6 years ago in reply to Emmanuel Tillol

TI__Mastermind 25955 points

Hi Emmanuel,

I will look into why these values are not appearing in this release of bqStudio and provide you with an update by EOD Wednesday, at the latest.

Sincerely,
Bryan Kahler