In my Leaf, the last time I entered turtle the power limit started right before turtle (1-2 gids). It would be a interesting test that people with lost capacity bars check at what gid value the power bubbles start to disappear.
I would think it has to. Power output is a factor of C rating of the cells. Just for example let's use a 100 amp hour cell rated at 3C, which is 300 amps. If that 100 amp hour cell has lost 30% of it's capacity it's now at 70 amp hours of capacity, so 3C is now only 210 amps. Or to put out the original 300 amps it has to do it at 4.29C which will cause more voltage sag. You might not notice it until you demand maximum power but at some point diminished capacity has to result in diminished power output. Also the increasing relative C rate demands will probably further speed capacity loss since the cells will be working harder all the time. People might try some 0-60 runs and compare times to newer packs with full capacity.Volusiano said:Good logic, but I'm not so sure that there's a correlation between lower capacity and lower battery power. That's why Nissan is willing to warranty batter power output but is not willing to warranty capacity.JRP3 said:Eventually if the LEAF keeps dropping battery capacity it won't be able to deliver it's maximum power, and I think Nissan does guarantee that the pack can put out a certain amount of power. You might be better off just driving your pack into the ground in the heat and forcing Nissan to give you a replacement at some point. If you avoid driving the car you may just extend the pack life past the warranty period.
Does anybody have hard evidence that loss of capacity will eventually cause loss of power?
I think your logic would only work if there are only very few cells packed in the battery pack. But there are plenty enough cells packed in the battery pack that even diminished capacity caused by the drain of normal driving doesn't even diminish the power enough until you get to turtle mode because the current drain requirement from each individual cells is minimal given that there are so many cells in the pack. And even the diminished power in turtle mode may just be an artificial creation of Nissan to protect the cells from being fully drained.JRP3 said:I would think it has to. Power output is a factor of C rating of the cells. Just for example let's use a 100 amp hour cell rated at 3C, which is 300 amps. If that 100 amp hour cell has lost 30% of it's capacity it's now at 70 amp hours of capacity, so 3C is now only 210 amps. Or to put out the original 300 amps it has to do it at 4.29C which will cause more voltage sag. You might not notice it until you demand maximum power but at some point diminished capacity has to result in diminished power output. Also the increasing relative C rate demands will probably further speed capacity loss since the cells will be working harder all the time. People might try some 0-60 runs and compare times to newer packs with full capacity.Volusiano said:Good logic, but I'm not so sure that there's a correlation between lower capacity and lower battery power. That's why Nissan is willing to warranty batter power output but is not willing to warranty capacity.JRP3 said:Eventually if the LEAF keeps dropping battery capacity it won't be able to deliver it's maximum power, and I think Nissan does guarantee that the pack can put out a certain amount of power. You might be better off just driving your pack into the ground in the heat and forcing Nissan to give you a replacement at some point. If you avoid driving the car you may just extend the pack life past the warranty period.
Does anybody have hard evidence that loss of capacity will eventually cause loss of power?
Which is fine for the people who only need 70%, but lousy for those who were basing their decision to buy on the sole quantification of degradation that Nissan actually mentioned, 80% after 5 years.JRP3 said:The number of cells is irrelevant. If they all have diminished capacity their ability to deliver power as a whole has to be reduced. The only question is if that reduced power is still enough to meet the demands of the motor. Of course Nissan designed some cushion in the system so that the pack is capable of more power than the motor demands, so even a reduced pack may still provide enough power for the motor.
Now to somewhat contradict my earlier speculation that reduced capacity and greater strain on the cells would speed up battery degradation, I've seen a number of cycle life graphs for cells where capacity loss slowed down dramatically around 70%. If this holds true for Nissan's cells it could be why they are not worried, you may see an accelerated loss in hot climates but that may stabilize around the 70% mark. Their thinking may be if you were OK with 70% of original capacity after 5 years or so you should still be OK with that if it happens after only 2 years or so but holds steady after that. Only time will tell what actually happens.
Were these cycle life graphs done at different cell temperatures and still all stabilized around 70%? What about calendar loss graphs at various temperatures?JRP3 said:Now to somewhat contradict my earlier speculation that reduced capacity and greater strain on the cells would speed up battery degradation, I've seen a number of cycle life graphs for cells where capacity loss slowed down dramatically around 70%. If this holds true for Nissan's cells it could be why they are not worried, you may see an accelerated loss in hot climates but that may stabilize around the 70% mark.
That may be their thinking, but it is the lack of disclosure before the sale part that has those in hot areas up in arms.Their thinking may be if you were OK with 70% of original capacity after 5 years or so you should still be OK with that if it happens after only 2 years or so but holds steady after that.
I've been randomly recording these accounts of "getting 9 bars when charging to 80%":Randy said:Although I've read of more than one person whose first symptom is getting 9 bars on an 80% charge. At first it is once in awhile, but then it gets more frequent. A few weeks of that consistently and then they lose the 12th capacity bar...
Can you provide enough info to fill in the your details at http://www.mynissanleaf.com/viewtopic.php?p=213082#p213082" onclick="window.open(this.href);return false;?NOC8H18 said:Well I have lost 3 bars in 3 months. I took it in after I lost the first bar and was told it was normal.
2 weeks later I lost the second bar! I have not lost the third bar last week. Well it is back at the dealer and they are giving me the same BS of normal loss.
3 bars in 3 months does not seem "normal" to me..
NOC8H18 said:Well I have lost 3 bars in 3 months. I took it in after I lost the first bar and was told it was normal.
2 weeks later I lost the second bar! I have not lost the third bar last week. Well it is back at the dealer and they are giving me the same BS of normal loss.
3 bars in 3 months does not seem "normal" to me..
I wouldn't be too quick to draw conclusions from Nissan's lack of responsiveness, big companies don't respond quickly. Some companies have big cultural bureaucracies. Do we really think Nissan will sit by and do nothing about a two year old Leaf that has only 10 miles of range left?opossum said:Here's the story that ran last night on KPHO CBS 5 on LEAF capacity loss. It has both an article and a video at the top.
http://tinyurl.com/c8g9fzj" onclick="window.open(this.href);return false;
Outside of this, we really should "merge" this conversation from this point forward into the other thread that was linked above. Otherwise, we'll all have to start duplicating comments, as a lot of this has been and is being discussed in that huge thread in the Problems section.
GM is certainly a company with a big cultural bureaucracy, but Dan Akerson was publicly reassuring owners within a few days of the Volt fire non-issue hitting the mainstream media. At this point, after trying more polite forms of chiding it seems that nothing other than national exposure and/or lawsuits will move Nissan to act.LTLFTcomposite said:I wouldn't be too quick to draw conclusions from Nissan's lack of responsiveness, big companies don't respond quickly. Some companies have big cultural bureaucracies. Do we really think Nissan will sit by and do nothing about a two year old Leaf that has only 10 miles of range left?opossum said:Here's the story that ran last night on KPHO CBS 5 on LEAF capacity loss. It has both an article and a video at the top.
http://tinyurl.com/c8g9fzj" onclick="window.open(this.href);return false;
Outside of this, we really should "merge" this conversation from this point forward into the other thread that was linked above. Otherwise, we'll all have to start duplicating comments, as a lot of this has been and is being discussed in that huge thread in the Problems section.
GRA said:GM is certainly a company with a big cultural bureaucracy, but Dan Akerson was publicly reassuring owners within a few days of the Volt fire non-issue hitting the mainstream media. At this point, after trying more polite forms of chiding it seems that nothing other than national exposure and/or lawsuits will move Nissan to act.
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