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BQ4050: Learned Full Charge Capacity超实际容量256mah，则Full Charge Capacity只更新一次，下次循环不再更新

user3958356
Prodigy 131 points
Part Number: BQ4050
Other Parts Discussed in Thread: GPCCHEM

你好，现在有一个情况，BQ4050，批量中有些电池容量偏低，比如标6000mah的实际学习容量只有5000mah，那么如果Gas Gauging里面State里面的Learned Full Charge Capacity 填的6000（mAH）（多数电池在这个容量附近），那么充放一个循环后Full charge Capacity 变成5744mah，以后再循环多少次，还是5744，不再变化，Max Error 为8%。但是后面再怎么循环，也是改不过来，Full charge Capacity还是5744mah不变化。如果Learned Full Charge Capacity填的5000，则可以每次循环都更新不同的Full charge Capacity，比如5000，5080，5023…这样。这个问题有没有办法解决？

  • 0
    TI__Mastermind 25545 points

    已经收到了您的案例，调查需要些时间，感谢您的耐心等待。

  • 0 回复 Eirwen
    TI__Mastermind 38080 points

    Sorry for the confusion but it seems that the issue is that you have is you have a cell that is supposed to be at 6000mAh but most of them are around 5744mAh and your asking for guidance on what you should do. If the full charge capacity of the cells are 256mAh in difference than you should use a different cell manufacture since the cell gauge is not able to deal with that big of a difference cell to cell and still hold its accuracy. The cell manufacture with brand new cells are supposed to hold 1% or less in difference. 

  • 0
    Prodigy 131 points

    抱歉，我可能描述得不太清楚，并不是容量只有256mah，是批量产品中的个别电池的实际容量和设计容量超出了256mah的误差，比如设计容量6000mah的一批电池，实际有一些真实容量只有5700mah的容量，这个误差超过了256mah，达到了300mah，是这个意思。这时候电量计BQ4050循环时更新一次到5744mah之后,就不再更新FCC了，并且max error是8%，这样我说清楚了没有？这个总误差是5700/6000=0.95，误差了5%

    Sorry, I may not have described it clearly. It's not that the capacity is only 256mAh, but rather that there is an error between the actual capacity and design capacity of some individual batteries in the batch product that exceeds 256mAh. For example, a batch of batteries with a design capacity of 6000mAh actually has a capacity of only 5700mAh, which exceeds 256mAh and reaches 300mah. That's what it means. At this point, after updating the BQ4050 battery meter to 5744mah during cycling, it no longer updates the FCC, and the max error is 8%. Have I made it clear? The total error is 5700/6000=0.95, with an error of 5%

  • 0 回复 Vivian Gao
    Prodigy 131 points

    Sorry, I may not have described it clearly. It's not that the capacity is only 256mAh, but rather that there is an error between the actual capacity and design capacity of some individual batteries in the batch product that exceeds 256mAh. For example, a batch of batteries with a design capacity of 6000mAh actually has a capacity of only 5700mAh, which exceeds 256mAh and reaches 300mah. That's what it means. At this point, after updating the BQ4050 battery meter to 5744mah during cycling, it no longer updates the FCC, and the max error is 8%. Have I made it clear? The total error is 5700/6000=0.95, with an error of 5%

  • 0 回复 user3958356
    TI__Mastermind 38080 points

    Please wait for our response

  • 0 回复 Vivian Gao
    TI__Mastermind 38080 points

    There is still some confusion on the wording of your question but I believe you are saying that you see a deviation of the real capacity of the cell and what the battery gauge tells you? What battery chemistry are you using some cell chemistry might need to have there own special chemID made? Also can you send a screenshot of the GPCCHEM report email to validate that you are using the proper chemID that has less than 3% error difference. The easiest solution would be to re run a calibration but this will likely not fix the issue.

  • 0 回复 Vivian Gao
    Prodigy 131 points

    6000mAh lithium iron phosphate battery, using BQ4050, CEDV， According to the suggestion, impedance tracking is not used for lithium iron phosphate batteries. The following figure shows the "Full Charge Capacity" and "Max Error" values of different battery cells after cycling under different "Learned Full Charge Capacity" conditions. The green box represents the abnormal situation. According to the manual, if the learning capacity deviation exceeds the range of 256mah, the maximum update is limited to 256mah, but it will not be updated in the next cycle. It seems that the manual does not say so, but rather that each update is limited to 256mah, and after several updates, it reaches a value close to the true capacity. If it is a large capacity battery, it should be common for batch products to exceed 256mAh, right?

  • 0 回复 user3958356
    Prodigy 131 points

    Is it common for batch products to have a capacity deviation exceeding 256mAh for high-capacity batteries?

  • 0 回复 user3958356
    TI__Mastermind 38080 points

    This is highly dependent on the cell manufacture and would require the user to reach out on there own since we don't have that type of information.

    I would interpedently verified the capacity of each cell and reach out to the cell company since our battery gauges are less than 1% difference of real SOC if set up correctly.

  • 0 回复 Vivian Gao
    Prodigy 131 points

    Understood, the battery issue has nothing to do with you. I just want to confirm that BQ4050 will update its' Full Charge Capacity 'once in this situation (with a capacity error exceeding 256mah), and will not update it again no matter what? Instead of updating multiple times to approach the actual capacity.

  • 0 回复 user3958356
    TI__Mastermind 38080 points

    The BQ4050 has the ability to update the full charge capacity since it is able to see the real capacity from cell to cell. However with your amount of error difference from cell to cell of 256mAh than the user would have to be comfortable that the FCC especially in the start to be off by that amount but the accuracy should become better over time accounting that it doesn't have a harsh change in impedance as the cell ages.