Hello
I am a very few knowledge about gas gauge products, but please allow me such a basic question.
My customer had designed their product 6 years ago ( medical product) using BQ27500, and now their product
is in the market.
Customer is facing the return from maklet because of RM( ReMaining capacity) indicates around 30%
even though they had replaced to full charged new battery ( same battery Sanyo UF553436F 720mAh) in the same board.
Failure rate is around 7% (17 sets) in the 2500 sets
According to customer saying, they are checking the data using bqEVSW-- EV2300 - i2c -- their board,
and saw Cell 0 Chg DOD at EOC is 7000 ; for bad board, 0~1000 ; for Good board.
Also, as per customer's comment, they had charge C/3 relax 2.5hrs, discharge C/10 relax 5hrs, but nothing changed.
Customer and I think the cause may be depend on customer's application ( discharge 10% of Qmax and almost always charging ) or battery ,
but we want to clarify the reson, and make a corrective action.
Here I have a few questions .
I would like to have your advise within 1 week.
Q1
I had attached the original gg file , which is gave from customer; made by TI local 3years ago ( I was not in chargge of this project ).
Would you please check that gg file ?
I see IT enable is 00 hex.
So,I think IT is enable and BQ27500 learns the battery profile , and if there were any change of impedance which is more than C/10,
gauge will update the DOD.
So, the reason why of customer's phenomenon is Ra table may be changed ( learned ) .
How do you think about this?
I think if IT enable is desable (20hex) , DOD does not updated and phenomenon should not be occur.
Is above description wrong ?
Q2
What interval (minimum) is necessary for log file ?
Is the interval of data get every 4 seconds is enough?
.... I intend to ask customer following to try to make gg file by theirselevs.
: Prepare new battery==> Dis Chg C/5 -- relax 300 min -- Chg C/2 -- relax 140 min
: To have a log file
Q3
Would you have your commen/ advise t about the cause of the phenromenon ?
With My Best Regards
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