BQ27426: The correlation with the actual battery when the IC does not perform Self-learning.

The correlation is typically within +/-5% if the ChemID is a match.

Hi dominik,

Thanks for you reply!

Q1. What is the basis for a ±5% correlation? Can you provide a formula?

Q2. Does the ±5% correlation still hold true during the gradual aging process of batteries?

Q3. If Q2 does not hold, then in the case of batteries aging according to a 5% (100% - 95% ~ 90% .... .55%) step aging process, what is the correlation respectively?

Q4、Does the correlation ±5% still hold true when the Fuelgauge IC does not perform self-learning, and meets the conditions for FCC and RM updates afterwards (Qmax\RA is not updated)?

(8). RM, FCC re-simulation update when Reset is reset.
(9). Whenever Qmax is updated RM, FCC re-simulation is updated. The Qmax update typically occurs when the OCV voltage is sufficiently stable (dV / dt < 4 µV/s) or when it has been sitting for more than 5 hours.
(10). Whenever Ra is updated RM, the FCC re-simulates the update. The Ra update occurs at 15 impedance grid points during the discharge process.
(11). RM, the FCC resimulates the update every time Relax Mode is exited (i.e., when charging begins, or when discharging begins).
(12). RM, FCC re-simulation update whenever charge full cut-off occurs.
(13). RM, FCC resimulation update every 5 hours during standby.
(14). RM, FCC resimulation update every time the temperature changes to Delta T 5°C.

1、±5%的关联性的依据是什么？能否提供公式?

2、±5%的关联性，在电池逐步老化的过程中，仍然成立吗？

3、如果Q2不成立，那么在电池按照5%(100%-95%~90%.....55%)阶梯老化的过程中，关联性分别是多少？

4、FuelgaugeIC不执行自学习，满足FCC、RM更新条件的以后(Qmax\RA不更新)，相关性±5%，是否仍然成立？

#1: It's based on the DOD error for the match. If this exceeds 3%, we don't recommend the match. The additional 2% points are due to added errors, based on experience.

#2: yes

#4: no.

Hi Dominik

Thanks for your support.

We would like to confirm whether there is any other way to obtain the true RM value of the current battery by directly inserting an aging battery (the FCC of this battery is known), in addition to performing operations such as charging and discharging that can make the meter self-learning?

What I understand is that in this case, the RM value of the meter output is estimated with reference to the new battery. Is there a way to calculate this RM value and make it the actual value of the battery?

我们想确认下，直接插入一个已经老化的电池（这个电池的FCC是已知的），除了进行充放电等可以让电量计自学习的操作外，我们是否有其他方法能获取到当前电池的真实RM值？

我理解的是，在这个情况下，电量计输出的RM值是参考新电池进行预估的，那是否有方法对这个RM值进行计算，让它变成电池的实际值？

You'd have to set UpdateStatus to 3 and then perform a learning cycle. This will update the gauge's internal state to reflect the aged battery.

Because the battery is used as a backup after being loaded into the equipment, there is generally no charging and discharging action, so the premise of the above problem is that the learning cycle cannot be carried out. Please help me to reconfirm the above question based on this premise.

The gauge needs to measure cell resistance and chemical capacity. There is no other way around it. If you insert an aged cell, the gauge will interpret it as a new cell until it adapts over several cycles. My recommendation reduces this to one cycle. There is no zero cycle option.

Thanks for yur ansewer.

If the question is that we insert a new cell and maintan a 55% SOC for several month without charging and discharging, is there a way to get a correct RemainCapcity? we think the battery is aging, so that the RemainCapcity is not a correct value from Fuelgauge.

No. There is no way to get the aged Remaining Capacity without charge/relax/discharge/relax cycles.