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BQ35100: SOH Value

João Rego
Intellectual 286 points
Part Number: BQ35100

Tool/software:

Hello,

Can I read the SOH value during normal system operation (with a load attached)? I am asking because this has an impact on the SOH accuracy, which is worse with bigger loads.

Yesterday, my battery SOH was 45%, while today, after the battery rested, it was 86%. I also used the NEW_BATTERY command to force a new SOH value. I noticed that without this command, the SOH never goes up.

Thank you.

Best regards,

João Rego

  • 0
    TI__Mastermind 37761 points

    Hello Joao,

    What mode are you using on the gauge? Are you using the EOS mode?

    Regards,

    Adrian

  • 0 in reply to Adrian
    Intellectual 286 points

    Hello Adrian,

    I am using the STATE-OF-HEALTH (SOH) Mode.

  • 0 in reply to João Rego
    TI__Mastermind 37761 points

    Hello Joao,

    Can you provide a log file showing this behavior? Can you also send me the gg file from the gauge?

    Regards,

    Adrian

  • 0 in reply to Adrian
    Intellectual 286 points

    Hello Adrian,

    I have attached both the log file and the gg file.

    I started the test with the battery charged at 92% (SOH). I let it discharge for 20 minutes and waited around 10 minutes before transitioning the GE pin. After some manual transitions, the battery stabilizes at 43%. I let it rest for some hours and I observed that the battery voltage was increasing while the SOH was fixed at 43%. After that, I sent the NEW_BATTERY command and the battery SOH increased close to 100% and then decreased to 64% for some cycles of GE pin transition. Probably, if I let it rest for more time, the voltage will increase a little more and the SOH will be higher if I send the NEW_BATTERY command.

    Best regards,

    João Rego

    CR123A.gg.csv

    CR123A.log

  • 0 in reply to João Rego
    TI__Mastermind 37761 points

    Hello Joao,

    Did you also program the ChemID onto the gauge?

    I checked the log file and I am seeing some very weird behavior. First, the current is being reported as 0 throughout the entire file. Also, the voltage is randomly jumping. These problems are going to need to be addressed. Has this always been occurring?

    Regards,

    Adrian

  • 0 in reply to Adrian
    Intellectual 286 points

    Hello Adrian,

    Yes, I used Panasonic CR123A (Chemistry ID: 0616).

    I thought that the current was 0 because in SOH mode only the temperature and voltage are measured. BQ35100 Datasheet: "In this mode, cell voltage and temperature are precisely measured immediately after the GE pin is asserted."

    The battery's internal resistance made the voltage even lower during discharging, so I waited some minutes after the discharge before reading the SOH. The battery's resting state caused the voltage to slowly increase. The random jumping occurred because I reset the IC through the GE pin to update the voltage and temperature values.

    So, yes these problems have always been occurring.

    Best regards,

    João Rego

  • 0 in reply to João Rego
    TI__Mastermind 37761 points

    Hello Joao,

    I will need some time to look into this.

    Regards,

    Adrian

  • 0 in reply to Adrian
    Intellectual 286 points

    Hello Adrian,

    I let the battery rest for 2 days and here is the log file. At first, the battery voltage was 2992mV and the SOH was 64%. When I sent the NEW_BATTERY command and reset the IC, the voltage increased to 3012mV and the SOH to 92%. So, as I said previously if I let the battery rest for more time, both the voltage and the SOH will increase.

    Fullscreen CR123A_2.log Download 
    Thu Jan 16 10:30:16 GMT 2025

Device Version Info = 0100_1_02
BQZ Device Name = bq35100
BQZ Firmware Version = 1_02


Sample,DateTime,ElapsedTime,Control,Charge Accumulation,Temperature,Voltage,Batt Stat,Batt Alert,Current,Meas_Z,ScaledR,IntTemp,SOH,Design Capacity,LogRowTime(ms),LogStatus
1,2025-01-16 10:30:20,4.001,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,180,SUCCESS
2,2025-01-16 10:30:24,8.011,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,185,SUCCESS
3,2025-01-16 10:30:28,12.019,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,180,SUCCESS
4,2025-01-16 10:30:32,16.024,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,186,SUCCESS
5,2025-01-16 10:30:36,20.026,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,186,SUCCESS
6,2025-01-16 10:30:40,24.027,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,186,SUCCESS
7,2025-01-16 10:30:44,28.031,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,183,SUCCESS
8,2025-01-16 10:30:48,32.031,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,181,SUCCESS
9,2025-01-16 10:30:52,36.045,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,184,SUCCESS
10,2025-01-16 10:30:56,40.052,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,178,SUCCESS
11,2025-01-16 10:31:00,44.053,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,190,SUCCESS
12,2025-01-16 10:31:04,48.054,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,191,SUCCESS
13,2025-01-16 10:31:08,52.062,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,184,SUCCESS
14,2025-01-16 10:31:12,56.062,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,183,SUCCESS
15,2025-01-16 10:31:16,60.066,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,180,SUCCESS
16,2025-01-16 10:31:20,64.072,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,189,SUCCESS
17,2025-01-16 10:31:24,68.084,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,177,SUCCESS
18,2025-01-16 10:31:28,72.086,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,191,SUCCESS
19,2025-01-16 10:31:32,76.089,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,186,SUCCESS
20,2025-01-16 10:31:36,80.099,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,180,SUCCESS
21,2025-01-16 10:31:40,84.113,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,183,SUCCESS
22,2025-01-16 10:31:44,88.114,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,179,SUCCESS
23,2025-01-16 10:31:48,92.116,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,190,SUCCESS
24,2025-01-16 10:31:52,96.117,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,193,SUCCESS
25,2025-01-16 10:31:56,100.131,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,177,SUCCESS
26,2025-01-16 10:32:00,104.142,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,183,SUCCESS
27,2025-01-16 10:32:04,108.146,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,179,SUCCESS
28,2025-01-16 10:32:08,112.151,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,191,SUCCESS
29,2025-01-16 10:32:14,117.783,0x2080,0,24.9,2992,0x0001,0x0001,0,0,0,23.3,64,1450,181,SUCCESS
30,2025-01-16 10:32:16,120.169,0x2080,0,21.5,3013,0x0001,0x0001,0,0,0,21.0,92,1450,186,SUCCESS
31,2025-01-16 10:32:20,124.182,0x2080,0,21.5,3013,0x0005,0x0001,0,0,0,21.0,92,1450,190,SUCCESS
32,2025-01-16 10:32:26,130.312,0x2080,0,21.6,3012,0x0005,0x0001,0,0,0,21.2,92,1450,184,SUCCESS
33,2025-01-16 10:32:31,135.408,0x2080,0,21.8,3012,0x0005,0x0001,0,0,0,21.3,92,1450,183,SUCCESS
34,2025-01-16 10:32:32,136.212,0x2080,0,21.8,3012,0x0001,0x0001,0,0,0,21.3,92,1450,193,SUCCESS
35,2025-01-16 10:32:36,140.213,0x2080,0,21.8,3012,0x0001,0x0001,0,0,0,21.3,92,1450,190,SUCCESS
36,2025-01-16 10:32:40,144.215,0x2080,0,21.8,3012,0x0001,0x0001,0,0,0,21.3,92,1450,187,SUCCESS
37,2025-01-16 10:32:44,148.220,0x2080,0,21.8,3012,0x0001,0x0001,0,0,0,21.3,92,1450,183,SUCCESS
38,2025-01-16 10:32:48,152.229,0x2080,0,21.8,3012,0x0001,0x0001,0,0,0,21.3,92,1450,191,SUCCESS
39,2025-01-16 10:32:52,156.233,0x2080,0,21.8,3012,0x0001,0x0001,0,0,0,21.3,92,1450,185,SUCCESS

    I will still wait for your response.

    Best regards,

    João Rego

  • 0 in reply to João Rego
    TI__Mastermind 24931 points

    Hello, 

    Please expect a delay while we look into this. 

    Regards, 

    Jonny. 

  • 0 in reply to Jonny
    Intellectual 286 points

    Hello Jonny,

    I am still waiting for feedback.

    Thank you.

    Best regards,

    João Rego

  • 0 in reply to João Rego
    TI__Mastermind 37761 points

    Hello Joao,

    Sorry for taking while to get back to you. After discussing with firmware team and other senior apps engineers they have concluded that you should be reading SOH when there is an active load attached to the battery as this will affect SOH calculations. For testing, the gauge should be off for the majority of the time and that the battery should be discharged at the usually system load rate for the end application. The gauge should be enabled through the GE pin at periodic intervals, maybe once every 12 or 24 hours to take a voltage and temperature reading and report a new SOH value. Afterwards the gauge should be put back to sleep.

    Regards,

    Adrian

  • 0 in reply to Adrian
    Intellectual 286 points

    Hello Adrian,

    Thank you for your answer. I will use the gauge as you described. 

    I have a question about the new battery insertion. How can I detect when a new battery is connected? For example, if a new battery fully charged is inserted, the SOH will not increase to the new battery's real SOH until the new battery command is sent.

    Best regards,

    João Rego

  • 0 in reply to João Rego
    TI__Mastermind 37761 points

    Hello Joao,

    When a new battery is inserted this is a manual process that involves human intervention. I would have a way for the host MCU to know when the new battery is inserted so then the new_battery command is sent. Maybe a reset button can be implemented or some sort of other logic on the MCU side.

    Regards,

    Adrian