Herm
Well-known member
You guys wanted a hard number, now you have it.. 5 hours at 110° F, straight from the horse's mouth.
Herm said:You guys wanted a hard number, now you have it.. 5 hours at 110° F, straight from the horse's mouth.
Considering the numerous statements by Mr. Perry which have proved to be inaccurate and/or flat out wrong, are you sure you've got the right end of the horse?Herm said:You guys wanted a hard number, now you have it.. 5 hours at 110° F, straight from the horse's mouth.
I also have no confidence that our loss will "level off" as many seem to expect, and I feel we don't have enough data to support this belief. I would not be surprised if there is only a modest slow-down in the loss rate over the next year. The theory says shelf life loss goes as (time)^.5, but it is not clear to me how the accelerated loss due to elevated temperature is related to the shelf life loss process. The temperature may instead be accelerating the loss that is proportional (linear) in battery cycles.TonyWilliams said:Boomer23 said:I submit that we have a problem with the LEAF's pack in very hot climates, and we're seeing predictable range loss in other regions. The degree to which the latter is a problem relates directly to each owner's range needs and whether they are concerned about resale value loss, which may well IMHO be somewhat self-induced due to our own lumping of the predictable range loss in with the heat related problem.
I'm certainly not lumping, as I have plainly said my former LEAF's 15-18% loss in 15 months had nothing to do with temperature, and specified that the car has never been exposed to any "high" temperatures of any kind, ever. I also submit that I don't think that is the norm, or that my car was going to "level off", as is seemingly popular to say. It actually appeared to be in a free fall from even a month ago.
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I'm guessing you are joking ...Gonewild said:Phx in the summer the lows are 105f and 118 day time temps
Your theory forgets to take into account ambient temperature. It's already been shown that GIDs will go down as the average temperature goes up and will recover somewhat as the average temperatures goes down. Your plot covers a period of time which warms up significantly in Claremont, CA. The average high has climbed 5F from May through July this year from 82F to 92F (using Ontario Airport as data source).tbleakne said:I also have no confidence that our loss will "level off" as many seem to expect
tbleakne said:but in the meantime here is my loss data. "Day 0" is May 30, 2012.
The linear fit yields:
6.0 days per Gid of loss
5.0 Gids lost per month
10.7% SOC loss per 6 months.
JP, sorry to hear this. Some additional data about your case would be helpful:JPVLeaf said:I may be running in the same heat (doh! no pun intended) as you.z0ner said:I haven't lost a bar yet, but it's right around the corner. I've noticed significant range loss, an 80% charge only gets me 9 bars, and the GOM only displays 75-80 with 100% charge. My driving habits haven't changed, and still average 4.1.
19K miles
S/N: 909
Delivery Date: 4/18/11
Received my first 9-bar 80% charge this afternoon.
19.8k mi, days short of 14 mos.
For those that have lost the first bar, what were your Gid readings at 80% at that time?
For cycle loss lithium cells will lose capacity faster for the first few hundred cycles. After that the curve flattens. It's reasonable to assume the AESC cells will follow the same path.tbleakne said:I also have no confidence that our loss will "level off" as many seem to expect, and I feel we don't have enough data to support this belief. I would not be surprised if there is only a modest slow-down in the loss rate over the next year. The theory says shelf life loss goes as (time)^.5, but it is not clear to me how the accelerated loss due to elevated temperature is related to the shelf life loss process. The temperature may instead be accelerating the loss that is proportional (linear) in battery cycles.
I am primarily reporting data, not theory. Please don't reject my data. I just displayed a linear fit to limited data. My point is that despite the change in temperatures over these 60 days, the trend looks about linear.drees said:Your theory forgets to take into account ambient temperature. It's already been shown that GIDs will go down as the average temperature goes up and will recover somewhat as the average temperatures goes down. Your plot covers a period of time which warms up significantly in Claremont, CA. The average high has climbed 5F from May through July this year from 82F to 92F (using Ontario Airport as data source).tbleakne said:I also have no confidence that our loss will "level off" as many seem to expect
If the 60 day plot you are showing were a trend, your current GID count would be much lower since ~231 is what it should read when new - yet you only lost ~6 GIDs on an 80% charge in the first year of ownership, but now have apparently lost 10 GIDs in 60 days. Sorry, does not compute.
I agree that the thermal time constant is less than 24 hours. But I will also state that I think it is a strong function of the speed of the car since the airflow will quickly bring the battery case close to ambient. (The thermal time constants inside the battery case, OTOH, should be much more static. Presumably the thermal resistance from the case to the cells is quite low, which tends to imply a low thermal time constant, also.) The result is that the behavior of the bars is strongly influenced by *when* the car is driven. Specifically, if the car is driven in the hottest part of the day then the temperature of the battery case will quickly go to that level. If the car is simply parked for 24 hours, it just seems to slowly follow the ambient temperature around with about a 4- to 6-hour time constant. It certainly gives me pause to drive the car when it is 80F in the garage and 90F or hotter outside.tbleakne said:I also don't know what the thermal time constant of the pack is, but the transitions from 5 to 6 temperature bars and back again show that the time constant is much shorter than 24 hours. This tells me the 24-hr temperature history of the battery is important, not just the average ambient.
tbleakne said:... If your answers to the above questions are yes, this, together with your relatively high mileage would suggest that your loss is at least partially related to battery cycle count and temperature, and not just temperature and time. If so, I would put your case in the same class as 91040 and possibly TonyWilliams. The last I heard, 91040 was down to about 85% on the Gid meter for 100% charge.
vrwl said:tbleakne said:... If your answers to the above questions are yes, this, together with your relatively high mileage would suggest that your loss is at least partially related to battery cycle count and temperature, and not just temperature and time. If so, I would put your case in the same class as 91040 and possibly TonyWilliams. The last I heard, 91040 was down to about 85% on the Gid meter for 100% charge.
The history and limited data from my car might suggest that battery cycle count has nothing (or very little) to do with it. See my signature for additional GID data points.
DaveinOlyWA said:all of it plays a part. as to the degree i would rate them from worst to best
1) heat
2) time
3) charge cycles
I'm not sure what Perry's background is, but my impression since last year is that his position [Nissan North America Product Director] with Nissan North America is that of "chief flack". I think his off-the-cuff pronouncements should be taken with a big grain of salt.GRA said:Considering the numerous statements by Mr. Perry which have proved to be inaccurate and/or flat out wrong, are you sure you've got the right end of the horse?Herm said:You guys wanted a hard number, now you have it.. 5 hours at 110° F, straight from the horse's mouth.
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