BQ40Z80: Cell 7 Lifetime Data

Hi Klaus,

The implementation of Cell Max/Min voltage is very simple.  It is the maximum or minimum voltage measurement the gauge has taken.  This Cell 7 voltage 3401mV was measured by bq40z80 in your 24-hour testing and then recorded.   

Andy

Hi Andy,

thanks for your answer.

I think I know how the Lifetime collection works or what its purpose is.

My question was why the voltage of Cell 7 is about 60mV higher than the others?
As you can also see in the Lifetimes (after 24houres)  there was no current floating and the battery was absolut relaxed.
So the voltages could not have changed and certainly not upwards!

So I think the measuremt of Cell 7 is not so good, because the bq40z80 measures here over a external voltage divider and
not direct like Cell 1, 2, 3 ..., isn't it?

What do you mean?

Thanks for helping us.

Klaus.

Hi Andy,

in this related thread,

you wrote this:

Maybe this could also be the cause for the not real value of "Cell 7 Max Voltage" in Lifetime_Data?

Thanks for helping us.

Klaus

Hi Andy,

the information out of this thread,

could also be the cause for the incorrect measurement of Cell 7, I think.

What do you mean?

Thanks for helping us.

Klaus

Hi Klaus,

The different measurement methods might explain a bit higher Cell 7 voltage readings.

Could you let the battery relax for a few hours and at the same time have the bqStudio log all the cell voltages? I would like to see if it is possible to capture this kind of abnormal voltage measurements.  If so, I will work with other teams, trying to solve this issue.

Andy

Hi Andy,

thanks for your answer.

I have just started the logging.

I will come back with the result.

Klaus

Hi Klaus,

Let me know when your results are available. Thanks.

Andy

Hi Andy,

now I have logged some data. The data was logged over about 28 hours.

The SOC of this Pack was another than in the first post.

At the beginning of the logging the Lifetimes looks like this:

After 28hours it looks like this:

The data logging has following min / max values captured:

Here is the curve over time for Cell7 and as comparision Cell4:

As you can see there are spikes in the measuremet of cell 7.

The values max values in curve/logging are smaller than the max values from the lifetimes.

Thanks for helping us.

Klaus

HI Andy,

here are the logging values as *.xlsx

Auswertung.xlsx

Or should I post it as *.log - File?

Thanks for helping us.

Klaus

Hi Klaus,

Thanks for your log file.  I will take a close look at your data.  Also, I will check internally and see if we can figure out something to solve that. 

Andy