data/text/DLP1/899581

BQ27520EVM: battery SOC suddenly drops to 0

Hello technical support： At present, we have successfully learned the battery charge curve on the bq27520evm. Were also strictly according to the learning cycle document and get the dffs with STATUS = 2. When we use the EVM to test the accuracy of the battery charge curve , we found that if we use a larger load (2A) , the SOC will directly jump value to 0 from a large value . The watch log is shown in the figure below. The log and ggfile of the whole process are also provided in the attachment, please help to check this problem. Thanks ! 200423.rar

We will take a look and get back to you. Andy

I see in your gg file, the chemistry id 3359 is used. It is for a battery that operates from 4.35V to 3.0V. Did you use the GPCCHEM tool to find out this chemistry id? Can I see your GPC report? Also, did you see the same issue when you did the learning cycle? Thanks. Andy

Hi andy, Thank you for your review and reply！ I have used the GPC tool to conduct two chemical ID evaluations. One of the original data was generated by the battery manufacturer's charge and discharge test , and the other one was generated from bqstudio . Both two tests are strictly followed the GPC data collection document. Could you please help me to see if these two chemical IDs can be used , will it cause the above problems? Do I need to learn chemistry ID again ? Reports are in the attachment. data-report1.zipdata-report0.zip In addition, we use 1 / 7C discharge rate training (900ma) in the learning cycle, but the discharge current of the typical application is about 2A. Is this the main reason cause above problems? Do we need to use 2A discharge current during the constant current discharge step during learning? But I worry that may cause a fail learning due to the discharge rate recommended in official document is 0.1C ~ 0.2C.

Yes, you can increase the rate so that we need to be above 0.1 C for learning cycle.