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BQ27742-G1: urgent !! getting problem after having done learning cycle process

Reena Patel
Intellectual 375 points
Part Number: BQ27742-G1

Hello,

I have completed learning cycle process. But as mention in datasheet that i need to put value in data memory as specified by battery. and i do same thing i set terminate voltage at 3000mV. But now i need to change that value to 3600mV as my project requirement. and i change that value to 3600mV. But dont know why fuel gauge is not work properly as it has to. i think problem is that different value updated in register while learning cycle and now 3600mV value is different from register value.

if i take 3000mV as termination voltage  then gauge wakes up at 3700mV( Design capacity ).

And if i take 3600mV as termination voltage then gauge does not wakes up even after 3800mV of battery. so where is the problem that i am making.?

Please mention all parameter from data memeory that i need to see for terminate voltage and wakes-up gauge (basically at SOC from 0% to 1% and SOC from 1% to 0%)

Should i need to do learning cycle again with 3600mV. and if i will do . Can i get successful learning cycle.

Fuel gauge : BQ27742-G1

Battery :Tenergy 3.7V 1400mAh 18500 Li-ion battery.

And one more question whenever i put battery in socket .. all capacity related terms change every time. 

Thanking you,

Reena Patel

  • 0
    TI__Mastermind 42535 points
    yes, if your application demands or needs a 3.6V terminate voltage, you'll need to repeat your learning cycle with a 3.6V terminate voltage. A battery insertion will cause a resimulation of capacity depending on the battery voltage, temperature and other IT parameters. So, they will be different every time you do that. However, with the same battery voltage you should get nearly the same capacity reading.
  • 0 in reply to Batt
    Intellectual 375 points
    Hello sir,
    As you told me that i have to do learning cycle again with 3600mV, and for that i set my terminate voltage as 3600mV and start manual mode in learning cycle, and in notification area as i need to set terminate voltage for learning cycle. but it does not take above value of 3400mV. so is this not possible that i can take 3.6V as termination voltage.
    but i start with 3.4v as my term voltage and make change in data memory also by taking 3.4V terminate voltage.
    and start learning cycle process. First dischage the cell, put it in relax mode after that and start charge the cell as notify me by BQ.
    But i observe wrong DOD0 -14241 .
    i think it should be above 16350.
    After connecting charger, at SOC 100% charger disconnect automatically even it was connected and FC bit was not set at 100% . And capacity was not full as well. so what was the problem ?
    why DOD is low??
    and one more thing as i check data memory after start leaning cycle. Update status still indicate 06 hex. as i have already done learning cycle before. but it should indicate 00 maybe as i have started new cycle .
    please solve all my query and please response me fast. Thanks for your support.

    Thanking You
    Reena Patel
  • 0 in reply to Reena Patel
    TI__Mastermind 42535 points
    When you restart your learning cycle you have to reset both the update status to 00 and set your Ra Flags to FFFF and FF55. Then change your terminate voltage and then the other gauging parameters relevant to your application. Once this is done, send reset, then IT enable, reset again. Wait until the battery is relaxed and then start charge. You have to start the LC with a fully discharged battery.