BQ34110: State of Charge not measuring correctly

Hello Derek,

Can you also share the logs you sent to the GPCCEDV tool with the resulting report? What are your battery specifications? You will need to change other parameters in the gauge like design capacity as well before testing.

Sincerely,

Wyatt Keller

CEDV report from TI attached as well as the original log files uploaded including the Config.txt.

Battery is Tenergy 31383:

Tenergy LIFEPO4 12.8V 10Ah Pack SLA Battery Replacement (DGR-A)

LiFePO4

12.8V nominal

9900mAh capacity

Charge voltage: 13.8V

Max charge current: 4A

Thank you,

Derek

CEDV20201223-report.zipCEDV20201223.zip

Hello Derek,

It looks like one of your low temp logs failed to find a good enough match to calculate the parameters well.

It also looks like your CEDV profile isn't programmed correctly in the .gg file.

Sincerely,

Wyatt Keller

Thanks; I just saw that the values don't match. Argh. On the low temp / high rate, if we run it with a different current (e.g. 2.5A instead of 3.5A that we have been using) then will we need to redo all the high rate tests with this new current?

I will reprogram the CEDV values. Do I only need to add the following parameters? (in addition to stack voltage, numCells, etc. that I already have)

EMF 3083
EDVC0 58
EDVC1 0
EDVR1 198
EDVR0 243
EDVT0 3836
EDVTC 9

What about the other three parameters; do I need to do anything with them?

VOC75 13273
VOC50 13164
VOC25 12966

Also, where can I find a definition of what EDVC0, EDVR1, etc. mean? Is there a slide deck or something that explains? I got the gist of CEDV gauging but I'm hazy as to the details.

Much thanks for your timely response BTW.

Hello Derek,

You should be able to re-submit with the current in that log changed.

I'm not aware of any documents, I'll look around to see if we have some on the ti.com page. The parameters are R and C values used for modeling the battery. You should also upload the OCV11.txt data to the gauge.

Sincerely,

Wyatt Keller

Thanks, for the OCV11.txt information (voltage at various levels of discharge) when programming it into the dataflash, do I program in the STACK voltage or the CELL voltage? The contents of OCV11.txt are below.

Also, on another fuel gauge e2e post, I saw that Design Voltage should be the stack voltage (for this, 12800mV) - is that correct for the bq34110 too?

I really wish there was an explanation for each parameter in the dataflash - what is this value, and how do I set it. Also it would be very helpful for TI to create a couple example tutorials for configuring the fuel gauge, both for single cell battery and multiple cell batteries. 

SOC, % OCV, mV
0 2725 10900
10 3058 12232
20 3104 12416
30 3130 12520
40 3141 12564
50 3145 12580
60 3152 12608
70 3178 12712
80 3184 12736
90 3186 12744
100 3236 12944

Hi Derek,

Design voltage is the nominal voltage of your pack.

Best regards,

Hello thanks, there was also another question:

For the OCV11.txt information (voltage at various levels of discharge) when programming it into the dataflash, do I program in the STACK voltage or the CELL voltage? The contents of OCV11.txt are below.

SOC, % OCV, mV
0 2725 10900
10 3058 12232
20 3104 12416
30 3130 12520
40 3141 12564
50 3145 12580
60 3152 12608
70 3178 12712
80 3184 12736
90 3186 12744
100 3236 12944