• State
  • Locked Locked
  • Replies 6 replies
  • Subscribers 64 subscribers
  • Views 1301 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ40Z50-R1: Incorrect FCC with Solar Charger

Antonio Fadhel
Genius 9410 points
Part Number: BQ40Z50-R1

Hi team,

Please see the issue below one of my customers is having with incorrect FCC in their solar-powered system. My guess is that since the charger input power is regulated, the lower charge current under low solar exposure is seen as the term current and triggering a valid charge termination (updating Qmax). What would be the recommended approach/settings for this system?:

I have one question about the GAUGE_EN function in the BQ40z50-R1. For what I see from my tests this bit needs to be enabled for cell balancing to occur, but it will also cause that Qmax updates are done. What has been happening is that sometimes our equipment doesn't charge the batteries fully, then a Qmax measurement is taken and the full charge capacity decreases.

We would like to know if there is any way in which we avoid this since we use solar energy to charge the cells and sometimes the weather does not fully help us. If that reading is taken and the equipment was not fully charged by our solar panels, we will have a mistaken measurement for the full charge capacity. It is not that the cells have decreased their capacity, but that they were not fully charged.

Thanks,

Antonio

  • 0
    TI__Guru* 76230 points
    Hi Antonio,
    For charge termintion to be detected, the taper current and taper voltage conditions has to be met. So i can see the taper conditions being met due to the reduced current due to the weather, but i don't see how the taper voltage condition will be met hence a valid charge termination would not occur.
    For the taper voltage condition, the battery voltage +taper voltage has to be greater than the charging voltage before the taper current conditions starts being checked for. So if you are indeed getting charge termination, it means both conditions are being met. you will need to include your gg and log files so we can check to see what is going on. FCC decreasing could be due to something else and not what you think, but without a valid log file, there is no way we can know the actual scenario.

    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Prodigy 220 points

    Hello I am Antonio's customer,

    Attached find the .gg.csv file. We have been experiencing full charge capacity updates and currently the value is way lower than the design capacity. This is a problem to us since we monitor the state of health of our battery pack to know when it is necessary to change them. If the state of health drops and it is not because of the cell's degradation, but because of the battery not charging to its full capacity, we might trigger the alarm and the batteries would be ok.

    I hope the files can help you see what our mistake is. I will attach the log file tomorrow as soon as we complete one cycle for you to see.Configfile.gg.rar

    Best regards,

    Luis Pinillos

  • 0 in reply to Onyx Ahiakwo
    Prodigy 220 points

    Cycle.log

    Sorry for the late reply, here is the cycle log. Please tell me if this log is good enough or if you need another one.

    Thanks,

    Luis

  • 0 in reply to Luis Pinillos
    TI__Guru* 76230 points

    Hi Luis

    I reviewed your files and it appears you are not having valid charge termination occur. FC flag is not getting set. Without FC getting set, you will never have a DOD@EOC occuring and that that could introduce errors in FCC. Can you adjust your charge termination conditions such that FC flag gets set. Perhapss allow charging to continue for a little more even after the taper current programmed in the data flash has been reached.

    thanks

    Onyx

  • 0 in reply to Onyx Ahiakwo
    Prodigy 220 points

    Hi Onyx,

    I have been running some tests and I think that maybe when the update happens, it is due to the low current that the panels give when there is not enough sunlight. Maybe this can be fixed by changing the charge term voltage setting. Currently I have it at 75mV (default), I guess this means that it considers the term voltage at a 75mV difference from the previously known term voltage? I am not quite sure how that setting works, but I am guessing that maybe changing it to a lower value would fix the problem?

    Best regards,

  • 0 in reply to Luis Pinillos
    TI__Guru* 76230 points
    Hi Luis,
    Pls see the valid charge termination section in section 4.6 of the TRM. It describe how the charge term voltage is use. I do not believe adjusting that value will solve your problem. For FC to be set, the current needs to go below the charge term taper current as described in section 4.6. Pls review that section and make adjustments to your charging appropriately

    thanks
    Onyx