received this battery with FCC 458mAh. cells' IR was about 80mOhm and cells voltage were normal under load. I changed the FCC to 4500 and calibrated twice on laptop. laptop ran for more than 5 hours. on every cycle FCC drops by 256mah. ran third calibration on NLBA. measured capacity was 6481 and chip decreased 257mah again. faced the same issue many times in Dell batteries only.
what could be the reason and how to solve.
discharging for 1 hour was also quite normal
You need to paste the whole dischargelog.txt from 100% to 0% SOC
You need to paste the whole dischargelog.txt from 100% to 0% SOC
in the end, discharging stopped as ground wire was disconnected accidentally 
. then SoC became 0 and discharging was refused by NLBA(ignore soc was not selected).
This happens because of cells specific discharge curve which is set in firmware.
Cells installed in this battery are 4.4v Lihv Lipos and they will be considered empty at around 3.5v because of the rapid voltage drop if discharged further.
At least this is the official data according to cells manufacturer which from my experience is not 100% true.
But to answer your qestion, ( if this behaviour is normal for this battery?) the answer is YES.
There is nothing wrong. It's just specific firmware settings according to cells manufaturer datasheet.
I have edited my own Dell laptop battery and got 1 extra hour of runtime and cells behave absolutely normal when dischared below 3.5v
But such service can't be offered to customers since battery becoming unstable is still an option.
Me have noticed similar issue on Dell batteries as well. After dropping RSoC to 7% battery continues discharge from an half to and hour without significant voltage drop. Real voltage drop started after 3300...3200mV so at 3.5v characteristic is still stable. Me dont know how these batteries were performed while were knew because me received them used after long storage.
Such an issue could be explained by following assumptions
- cells profile was initially not properly preprogrammed on the factory
- chip was preprogrammed to work with one specific cells but due to lack in stock pack maker used another cells
- chip was preprogrammed correctly, but cells characteristics deteriorated over time and dont not match available profile
The issue could be resolved by analyzing discharge curve and loading new cells profile. TI even has dedicated tool to calculate new EDV/EMF constants basing on discharge log. But this method is quite complex and could be done by only experienced battery technician
Me have noticed similar issue on Dell batteries as well. After dropping RSoC to 7% battery continues discharge from an half to and hour without significant voltage drop. Real voltage drop started after 3300...3200mV so at 3.5v characteristic is still stable. Me dont know how these batteries were performed while were knew because me received them used after long storage.
Such an issue could be explained by following assumptions
- cells profile was initially not properly preprogrammed on the factory
- chip was preprogrammed to work with one specific cells but due to lack in stock pack maked used another cells
- chip was preprogrammed correctly, but cells characteristics deteriorated oved time and dont not match available profile
The issue could be resolved by analyzing discharge curve and loading new cells profile. TI even has dedicated tool to calculate new EDV/EMF constants basing on discharge log. But this method is quite complex and could be done by only experienced battery technician.
Yes exactly same observation as mine. My personal laptop has a 9NJM1 genuine battery. I own it since brand new. Cells already have 300+ cycles.
I was able to observe cells behaviour form brand new state and they were really delivering the expected desing capacity until 3.5v. But as they age and develop higher IR they just can't manage to deliver expected capacity at such hight threshold anymore.
Adjusting EMF/EDV solves this problem but it takes multiple attempts until you set the correct values.
@bnbplus We can try adjusting these values in your battery since we can see that the voltages are quite stable but make sure you inform the customer, and make sure he agrees.
Also if such procedure will be done make sure you back up the original eeprom image so if results are not satisfactory you can flash it back to the chip.
But as they age and develop higher IR they just can't manage to deliver expected capacity at such hight threshold anymore
So pack maker did not properly set aging parameters. Compensated EDV gauges allow aging correction due to capacity decrease and impedance increase. But their calculation is not an easy task so TI recommend to use their tool for it.
@bnbplus We can try adjusting these values in your battery since we can see that the voltages are quite stable but make sure you inform the customer, and make sure he agrees.
Also if such procedure will be done make sure you back up the original eeprom image so if results are not satisfactory you can flash it back to the chip.
customer agrees and eeprom already saved. pls inform when you get time.
We can try adjusting these values in your battery since we can see that the voltages are quite stable
after adjustment by @torture FCC was 6400 and MaxError 100%. forgot to save screenshot.
fully charged in NLBA.
then fully discharged to 0% in NLBA.
after this FCC became 6365 and MaxError 2%.(didn't save screenshot)
then ran one cycle of charge/discharge on laptop and FCC decreased 256 and MaxError stayed at 2%.
will FCC keep on decreasing?
will FCC keep on decreasing?
This depends on cells. Right now discharge log looks as it should be. There is no sudden drop in SOC like before so from software side everything is ok.
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