RegGuheert on August 28, 2017 wrote:Our 2011 LEAF lost its third capacity bar on Friday, August 25, 2017. Wife was driving, so I do not have a picture from LeafSpy, but I estimate the following numbers:
Our LEAF was manufactured in June 2011.
As I posted back in August, our LEAF dropped its 10th bar on August 27, 2017, right at a very typical level of 47.5 Ah. The reported capacity continued to drop through the Fall with the lowest reading of 46.88 Ah
coming on October 7, 2017. To me, this seemed like a rather rapid drop in capacity.
But the next time I took a reading was on November 13, 2017, when the car reported capacity of 47.48 Ah: a 0.6 Ah increase. Then on November 16, 2017, it was back down to 47.23 Ah and on December 7, 2017, it was at 47.21. I figured it had settled in for the winter since most winters I see no change in the reported capacity of the car.
That was not to be. On January 18, 2018, the car reported 47.39 Ah. Then the next day it reported 47.62 Ah, which is above the threshold for the drop of the 10th bar. (But there is hysteresis, so the bar has not come back.)
Skip ahead to yesterday and now the car is reporting 48.21 Ah
. That is an entire Ah higher than what was reported two months earlier on December 7 and 1.33 Ah higher than four months earlier on October 7.
So, is it real? I will say "Yes and no." The pack in our LEAF has always been limited by cell-pair #37, which is weaker than all the rest. This effect is particularly noticeable in the wintertime. But on January 17 I forgot to press the timer override button and ended up draining the battery down to a reported SOC of 5.9%. Cell-pair #37 was 328 mV below the highest cell-pair at that point, which was not a surprise. But I have to think that the BMS now feels that it has more capacity than it previously thought it had.
All this to say that I normally see no change, up or down, in reported capacity between about December 1 and March 1. This rise of 1.33 Ah has been entirely unexpected.