BQ40Z50-R2: BQ40Z50-R2

Hello Martin,

Can you send a log file of you attempting the learning cycle. I will need to see all the registers for me to help debug this issue. Also, can you send me the datasheet for the battery you are using.

Regards,

Adrian

Hello Adrian,

Ican you send everything!
i've just starte a new cycle, so if its okay i would send you the log of this.
The battery Pack is 16,8Ah and im charging with 3,5A and discharge with 1,8A so it will take a while.
Since the update status isn't changing to 05 is it okay if i'm sending you the initial discharge and the charge log firs, to be faster?
please find the battery Datasheet in the here:LPA975175 3.7V 16.8Ah 15C Cell.pdf
The ChemID suggested by your Tool is ID 113.
I will post the logs from dicharge and charge till FC as soon as they are ready!

Thanks for your help!

BR,

Martin

Hello Martin,

Thank you for sending the datasheet, I will wait around for the log file as this will give me more insight on the cause of the problem.

Regards,

Adrian

initial_discharge.log

Hello Adrien,
i've attached the log. It covers the initial discharge, the rest phase and the charge phase.

How ever because of an automatic Windows update, the system shut down... but i hope that the logs are containing what you're looking for.

I've also changed the flash slightly:
The REST bit is set, but update status is still 04

7752.data_memory_wip_28_10_2024.gg.csv

Thank you for your help!

BR,

Martin

Hello Martin,

So I see a few issues currently. First, some setting issues in data memory. Term Voltage should be set to 11V since the cutoff voltage of 1 battery is 2.75, 2.75 x 4 = 11V. In the log file, I see that in the initial discharge, the cell voltage goes down to only 12.7V. We want to discharge all the way down to 11V for the first discharge. Lastly, when charging the battery we want to achieve Valid Charge Termination.

I see there is a constant current charge, but you did not implement a constant voltage charge. You need to do a constant current charge until the voltage reaches charging voltage. Then you will need to do a constant voltage charge until the current is less than the defined taper current.

Should look something like this:

Regards,

Adrian

Hi Adrian,

thanks for the feedback. Term Voltage and fully charged PACK voltage levels: i see your point! My problem is, that the cells (even if they are from the same batch) are not in balance durring the charge or dischcharge phase. According to the tech sheet of the gauge cell balancing just works after a 0E in the update status register, so its a kind of a chicken egg problem.

I set those values to don't reach with a single cell the COV or CUV threshold. Is there any technique, how to get rid of the inbalanced cell problem during learning cycle?

Charging: the cahger is charging now with 16,8V wich is actually the max cell charging voltage x4. Thats the reason it behaves like a constant current charger. I can set this value lower so the characteristic will match the graph you posted. But till the balance isn't working, my actual capancity in [Wh] will be way less as the theoreticle capacity 16,8mAh*16,8V=282,24Wh.

How can i solve this issue?

Thank you!

BR,

Maritn

Hi Adrina,

I did another cycle with adjusted data memory settings.
I've set the Term Voltage to 11000mV as you recommended.

I've adjusted the charging voltage, so the cell with the highest voltage was still bellow the COV threshold, while the FC flag was set and a charge termination allso occured.
I've also attached he log files from the discharge and the charge. Unfortunatly my PC went down, therfore the charging logs are splitted in to two.

 I've played with the charger settings near to the end of the charging cycle to find the correct voltage value, where the COV hershold is not reached, but the FC is set and the term current is also reached.

I'm still don't get a 05 Status but i assume it's because of my try and error?

Is the discharge phase already okay, or do i still have to adjust something there?

Thank you!

BR,

Martin

initial_charge_2_1.loginitial_charge_2.log

data_memory_wip_28_10_2024_3.gg.csvinitial_discharge_2.log

Hi Adrien, 

just a quick update: since the cells are not balanced, the cell 2 reached the Shut Down voltage in the discharge pase:


So the ballancing is still an issue... any idea how to solve this?
Should i set the FD and related settings higher?

Hello Martin,

We will need to find a way to manually balance the cells. Are you able to configure all 6 cells in parallel. When the cells are in parallel, they will slowly start to balance themselves.

Regards,

Adrian

Hi Adrian,

i repeated the learningcycle with new, way smaller cells.
i selecteds the ChemID with your Tool ad uploaded it to the Gauge.

I've adapted the settings in the Data Flash of the gauge to the new cells.
The update status is 05. I have problems now with the discharge part:
The cell values are hitting the Term and TermC voltage, FD and TD values are also reached, but the discharge continues till one of the cells reaching the CUV...
Attaching the log and the flash content. I had multiple tests in a row to see if im adjusting some settings is it getting better... just check out the last discharge from 3%. Cell 4 reaches the CUV and then discharging is stoppong.

I assume that it's not okay to hit the CUV every time. Can you help me with my settings?

Thank you!

BR,

Martin

Hello Martin,

Can you send me the log file for this data. Might seem to be an issue with cell imbalance. I would disable the CUV protection for the learning cycle test and make sure to cut off current when one of the cell voltages get too low.

Regards,

Adrian

Something went wrong with the attachment, sorry!
Log life and flash:
0844.data.gg.csvdischg_4.log

Hello Martin,

Thank you for the data, please allow me some time to review it.

Regards,

Adrian

Meanwhile i continued trying to get the learning done. What i faced:
Even if the XDSG is set, the Gauge reports a 3mA DSG...

Is this a HW issue or Calibration? How can i get rid of this? The REST flag isn't set...

Thanks!

BR,

Martin

Hello Martin,

This is likely a calibration issue, did you calibrate the gauge before?

Regards,

Adrian

Hello Adrian,

The problem was, that the CAL_EN flag was 1 as visible on the previous screeshot. I had to manually set it to 0 with the CAL_TOGGLE command.
The learning was successful! No the Update Status is 0E!

In the next step i've disconnected the battery pack and manually discharged one of the cell to check out the cell ballancing feature. After this i've restored everything.
That brings me to my next problem: the cell balancing is enabled, and in the operation status B high register CB turned to 1, but i don't see any effect on the cell itselfe. i did another charge-discharge cycle to see if something happens, but the voltage difference remains the same.
I've attached the data memory content and the log. ImbalanceTest2.log4718.Data Memory.gg.csv

Can you help me with this?

Thanks!

BR,

Martin

Hello Martin,

The cell imbalance between cell 1 and the rest of the cells is pretty large. This will take a very long time to balance and will not happen quickly. It is recommended to manually charge the cells individually so all batteries start balanced.

Regards,

Adrian