bq40z60EVM - LiFePO4 irregular ChgVolt/ChgCurr

Hi Daniel,

Are you referring to CHGV and CHGC in safety status register C+D? (apologies in advance if this is not what you are referring to).
If you are using bqstudio, you can set threshold values for these flags on the data memory tab under "protections". CHGV and CHGC are located near the bottom of the list.

Best Regards,
Ben Lough

Hello Ben, 

I appreciate your help.
No, these are not the values I am referring to. CHGV and CHGC actually do not change between my different test scenarios, and are not activated on my testings.

I am referring to the ChgVolt and ChgValues that are displayed on the Log file. 

Thank you for making it more clear, by the way!

Best,

Daniel Gebbran

Hi Daniel,

Try going to the data memory tab, Advanced Charging Algorithm, Standard Temp Charging and changing the values for Voltage and Current Med.

Page 60,61 of the reference manual might be useful to you: www.ti.com/.../sluua04c.pdf.

Let me know if this helps.

Best Regards,
Ben Lough

Hi Ben,

Thank you for your prompt response.
At the moment, I have made all Voltage and Current the same throughout all temperature ranges. Also, the values that appear for my ChgVolt/ChgCurr are exactly those I input at the Voltage and Current Med, at the Data Memory tab. Changing those values result only in different values for ChgVolt/ChgCurr, but not when those are activated.
Also, I have tested with two different BMUs, so to ensure it was not a Hardware problem.

I appreciate the help, once again.

Best,

Daniel Gebbran

Daniel,

Apologies for the late response. If you could export an .srec from your device and send it to me, I will load it on my bench and take a closer look.

Best Regards,
Ben Lough

Dear Ben

I appreciate your response.

The responsible for using the BMU said no reprogrammings were made to the BMU, it still has the original factory FW. He only changed the configurations and the calibration.

Unfortunately, I could not get to Unseal in the Full Access mode, nor to send the ManufacturerAccess() 0x0F00 (what I read is necessary for the device to enter the ROM mode and hence extract the .srec file).
I'm trying to do so on my end, but if you could also help me with which is the standard factory code for Full Access Mode enabling (I trief FFFFFFFF, 00000000 and a few others), it would save us some time.

Additionally, I am attaching the .log file compilation on .xlsx, if you want to have a look at it. 

https://www.dropbox.com/s/hijjxuf14yeyh0q/BMU_13.xlsx?dl=0

Best regards,

Daniel Gebbran
 

Daniel,

The default FULL ACCESS key is 0xFFFFFFFF. Could you tell me the state of [SEC1] and [SEC0] in your OperationStatus register? This will help determine what security mode your device is currently in.

Best Regards,
Ben Lough

Dear Ben,

Once again, I apologize for my lack of hands-on experience with the application.
The states of [SEC0] and [SEC1] are red (which I was assuming to be a 1).
Moreover on the .srec file, I have a question on sending the command for the ROM mode (0x0F00); at the Adv. Comm. SMB, under the Word Read/Writing, I should type, on the Send Cmd field, "0F", send the command, and "00", send again? 

 

I would like to rephrase my initial question of the whole topic, so to make the problem clear. I apologize for not putting in the following words sooner:

What makes the BMU trip into the "Charging Mode", in which it will accept charge once the AC source is back on?
Would it be measuring Voltage, or is it gauging the battery State of Charge, maybe measuring a certain discharge current over time? How does the BMU works?
I could find a lot of useful information on discharge and charging itself, but on this precise manner, I could not, and therein lies my problem.

Additionally, if it is not done so already, could such control be made from the actual Cell Voltages?

Thanks once again, and best regards,

Daniel Gebbran

Daniel
You mentioned that you are operating with default data flash parameters and the e2e post title says that you are using LiFePO4 cells. If so, the default parameters are setup for Li-Ion cells and will need to be adjusted to support proper operation with the LiFePO4 voltage range.

Tom

Dear Tom,

I have changed the values of operation in the Advanced Charge Algorithm, on Data Memory, accordingly to my operation (which involves very cold temperatures). Additionally, I have tested with both the Chemistry Programming on default (Li-Ion) and adjusted for the proper battery (A123's LiFePO4).

Where else must I change for proper voltage range operation?

Also, thanks for your reply.

Best regards,

Daniel Gebbran

Dear Ben, Tom,

Another piece of information that might prove to be useful:

The registers XDSG and XCHG, as far as I understand the BMU functioning, would be ideally either On and Off, or Off and On.

When the troublesome condition takes place, both are set high. Therefore, even after a full discharge, when XDSG is high, the XCHG has not been reset back to low; instead, it remains high. 
What determines this condition? I could not find its root in the documentation.

Once again, I appreciate your help.

Best regards, and have a wonderful weekend,

Daniel Gebbran

*Image below for additional status*

It is acceptable to have both the XCHG and XDSG flags set at the same time. They are set to the opposite states of the CHG and DSG flags. The SS flag is set, indicating that there is a safety fault and it is CUV in your case. I would check to verify that the CUV threshold is set properly for your cells. The curious problem is that both the FC and FD flags are set. You probably have some setup problems. Please export an srec file and send it to us. You will probably need to return the gauge to Full Access Mode to export the file.

Dear Tom,

Thanks for explaining that.
When acquiring the .srec file, I need to get into ROM mode. I have a question on sending the command for the gauge to enter ROM mode (0x0F00); at the Advanced Communication SMB tab, under the Word Read/Writing section, I should type, on the Send Cmd field, "0F", send the command, and "00", send again? 

Thanks,

Daniel Gebbran

Daniel
the bqStudio program will place the gauge into ROM mode before it exports the file. You just have to select a name for the file and press the Read Srec from Device button. You did have to send the 0F00 command to place the gauge into ROM mode when using the bqEVSW programs.
Tom

Dear Tom,

I apologize for the delay obtaining the .srec. Here it is.

Thanks again,

Daniel Gebbran

Dear Tom,

Are there any updates on this matter? I still cannot find a way to properly control at which moment the charging should start. This is crucial for my application.

Best,

Daniel Gebbran

Daniel
The TI IT department blocks Dropbox access. Can you attache the srec directly to the e2e posting?

Tom

FWfile.rar

Let me know if the upload has worked successfully.

Thank you,

Daniel Gebbran

Yes, I was able to download the file. I will check the file.

Daniel

I programmed your srec file into my EVM and it quit communicating. I will have to get a replacement to try it again.

Tom

Dear Tom,

Have you had any update on this matter?
Do you need a replacement of my srec file?

I have tried to operate my charging procedure by using the Cell Over Voltage (COV) and Recovery Voltage as the intended charging voltage. However, by doing so, the cells do not get balanced, even though the recharging takes place as soon as the lower Recovery Voltage is achieved.

Best,

Daniel Gebbran

Daniel
Yes, send your latest srec file and a log file showing the problem and I will look at it again.

Tom

Dear Tom,

Please find attached. 

new.rar