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BQ27Z558: Fully charged battery is not maintained after unpluging charger

Jaiyong Park
Prodigy 100 points
Part Number: BQ27Z558
Other Parts Discussed in Thread: BQSTUDIO, GPCCHEM

Tool/software:

1. 100% Setting : 4.38 V - > Fully charged by charger

2. Battery voltage drops by 20mV and battery gauge is 99% immediately after removing the charger

Is there any way to figure out this issue with fuel gauge IC?

ex) edit register value

P.S it will be helpful if you can offer any kinds of document about BQ27Z558's register.

Thanks for you supporting!

Jaiyong Park

  • 0
    TI__Mastermind 25225 points

    Hello Jaiyong,

    Can you send a .log file from BQStudio to better debug this issue, however without looking at your data it could be how set your charge termination configuration parameter set as.

    Thank you,
    Alan

  • 0 in reply to Alan Frias
    Prodigy 100 points

    Hello Alan,

    Battery was attached in PDA and charged by charger. Therefore, it is difficult to log the charging through BQStudio.

    Thank you,

    Jaiyong Park

  • 0 in reply to Jaiyong Park
    TI__Mastermind 25225 points

    Hello Jaiyong,

    Can you sent your GPCCHEM report to validate your chemID and also can you confirm that you performed a calibration on your system along with a learning cycle and updated your design parameter based on your cell. Also can you attached your cell datasheet 

    Thank you,
    Alan

  • 0 in reply to Alan Frias
    Prodigy 100 points

    Hello Alan,

    Here is the GPCCHEM report of my battery, and I applied below ChemID.

    7522 1.56 0.82

    Cell datasheet is confidential item, so I need to check whether I can share it with you or not.

    I'll upload cell datasheet if I can offer it.

    Thanks,

    Jaiyong

    1541.roomtemp_rel_dis_rel-report.zip

  • 0 in reply to Jaiyong Park
    TI__Mastermind 25225 points

    Hello Jaiyong,

    C=onfirm that your chemID is correctly selected than we would need to move forward with a .log file test exported from bqstudio that showcase the user charging the cell and it being disconnected and the SOC dropping from 99% from 100%. Without this file we would be blindly guessing.

    Thank you,
    Alan

  • 0 in reply to Alan Frias
    Prodigy 100 points

    Hi, Alan

    If capacity is confirmed as below, should I apply design capacity - 4200 mAh or estimate capacity in actual using range and apply it?

    Pack Manufacturer's Typical capacity : 4320mAh - 3.0V ~ 4.45V range

    Pack Manufacturer's Minimum capacity : 4200mAh(Cell 4220mAh) - 3.0V ~ 4.45V range

    Actual using range is 3.4V ~ 4.38V -> Unknown Capacity : Need to be estimated

  • 0 in reply to Jaiyong Park
    TI__Mastermind 25225 points

    Hello Jaiyong,

    Your design capacity could be labeled as "typical capacity" and for your case it should be 4320mAH, however if your voltage threshold for charging is set incorrectly and not based on the cell datasheet than you can see errors within your system.

    Thank you,
    Alan

  • 0 in reply to Alan Frias
    Prodigy 100 points

    Hi, Alan

    I tried again with attached setting, and I charged with application after uploading golden image.

    Then, battery was not fully charged with application

    Do you know what part caused this problem?

    Term voltage was 3000mV during learning, and I edited it as 3400mV after learning.

    

      

    1. 

      Charging was stopped at 95% (4349mV)
      

      2. 

    2. Battery voltage was 4327 mV when I unplugged charger
      3. 

    

    Register Setting After Upload this Learning.gg.csv
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
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                          TI__Mastermind
                        25225 points
                      
    
                          
                   		
		
    
					
    Hello Jaiyong, 
    

    We have received your update and we are working on your response.
    

    Thank you,
    Alan
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                 	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
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						in reply to Alan Frias
					
									
    
	
    
	                                    
                      
    
                        
                          Prodigy
                        100 points
                      
    
                          
                   		
		
    
					
    Hi, Alan.
    

    At first, I2C Gauging Configuration was 27.
    

     
    

    After I have changed it 27 to 04 - TAMB_SYNC_SIM ,RSOC_HOLD, RSOCL High to Low
    

     
    

    However, below case occurred.
    

    Please share any kinds of opinion about below.
    

      

    • Unused battery
      • 

    

      

    1. I2C Gauging Configuration : 04 
      2. 

    2. Charging battery with application and 5V3A Charger
      3. 

    3. 100%, Full was checked
      4. 

    4. After eject the charger, battery gauge dropped immediately. 100% -> 99%
      5. 

    5. After recharge the battery for few minutes, battery gauge was maintained as 100%.
      6. 

    

    

    Thanks,
    

    Jaiyong
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
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