turbo2ltr said:
The fact that many have reported rapidly dropping gid counts and Scangauge reports over the last few months, as temperatures have risen, seem to me, to indicate that either Nissan has equipped LEAFs with batteries with extremely poor resistance to hot temperatures, or that there is another factor at work.
I think you're barking up the wrong tree here.
I'm guessing you aren't familiar with typical charge profiles.
Temperature compensation during a charge profile is typically manifested as a voltage compensation. A typical charge profile will charge constant current until the batteries reach voltage X, then switch to a constant voltage until the current drops to Y amps. They typically will then switch to a low constant current until voltage Z is reached. When there is a temperature compensation, that will cause the BMS to adjust voltage X and Z. I don't know about other people, but I know I saw the full pack voltage after 100% charge yet I have two bars missing. So with that, my speculation is that it has nothing (or very little) to do with the BMS, and mostly to do with the batteries degrading in the heat.
I am trying to use other's quotes fairly to frame this question. Feel free to correct me if I have erred in any way, in this summary.
"turbo2ltr" So I charged last night to 100%.
GID is 213, pack volts is 393.75 (assuming I did the conversion right)
I lost the first bar at 228 gid.
http://www.mynissanleaf.com/viewtopic.php?f=30&t=8802&p=209773#p209773" onclick="window.open(this.href);return false;
Last October, TickTock reported:
Started charging at 11pm with 61 gids and 2 bars remaining
Ended 80% charge at 2am with 197 gids, 9 bars, 386V having drawn 11kWh from the wall
Started charging again at 10:20am with 197 and 9 bars
Ended 100% charge at 11:30am with 238 gids, 12 bars, 394V having drawn 4.3kWh from the wall
I guess I should mention my capacity guage still indicates 12 bars...
http://www.mynissanleaf.com/viewtopic.php?f=44&t=5582&start=120" onclick="window.open(this.href);return false;
Subsequently, IIRC, TickTock reported significant increase in "100%" charge gids/kWh capacity over the Winter, and a decline this Spring, also (I believe) all at the same ~394V. Sorry, I can't find his original post(s), just the re-posted graph here.
http://www.mynissanleaf.com/viewtopic.php?f=44&t=5582&start=350" onclick="window.open(this.href);return false;
"turbo2ltr" I believe TickTock's data to be correct and show higher GID at 100% charge with cooler weather. I cannot say if it's the BMS limiting it, or a factor of the chemistry. Maybe someone else knows.
http://www.mynissanleaf.com/viewtopic.php?f=30&t=9293&start=60" onclick="window.open(this.href);return false;
My question is, if the BMS was not limiting charge, as the pack voltage reports would indicate, what sort of battery chemistry could cause the large decrease in charge accepted, that TickTock reported, apparently due to higher battery temperatures, and the "recovery" to the significantly higher kWh charge his battery pack subsequently accepted, at lower battery temperatures?
Isn't this unexpected behavior from any Li-ion battery?
Do other extreme-climate LEAFs have gid histories over the last year, that differ from TickTock's experience?
In any case, as others have pointed out, another month or two of hotter weather is on the way for most North American owners. If Phoenix LEAF Batteries actually lost capacity at a near 1%-per-week rate this Spring, shouldn't we expect that rate would not slow much, and maybe even accelerate during the considerably hotter weather to come?
And LEAFs in not-quite-as hot regions, might be expected to lose their first bars in large numbers, as their Summer temperatures reach "Spring in Phoenix", correct?