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PostPosted: Mon Aug 13, 2012 2:48 pm 
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surfingslovak wrote:
DaveinOlyWA wrote:
interesting chart but i see a glaring issue with Minneapolis being warmer than Seattle. they are significantly colder making them significantly hotter in Summer and i think an analysis of sustained average temperature ranges is going to provide more accurate results.

Thanks for your comment, Dave. If you've read lukati's post above, you would see that this is exactly how it was done. There is not a lot of publicly available data out there, and we ended up sourcing temperature profiles from the same website. See further below to get an idea of how the profiles for Minneapolis and Seattle look like.

While we certainly can debate the validity of this data, I'm confident about the value I calculated for Minneapolis. It's within a degree or two of an empirically measured effective isothermal temperature published in a recent NREL study. It's so close that it can't be a coincidence.

As I said earlier, while I enjoy reading all comments on this board, I don't always agree with them. Especially if they are not based on hard data and models we can all compare against field data. Aside from Minneapolis and Seattle, this model predicts that both Hawaii and Florida are pretty hard on batteries. It should be interesting to see if and when we will get the first reports of lost capacity from there.

I don't mean to criticize, since you have a lot of EV experience, but I believe that we need to move away from a gut-feel approach to something more material and comprehensible to new EV owners. Tony demonstrated how it's done with his range chart. It's easily understood and very valuable. I wish Nissan came up with that, instead of their weasel response that "there is an infinite number of range scenarios".

Although there definitely is a nearly infinite number of temperature profiles and microclimates, I believe that it's important to come up with an easily understood chart that will give new owners an idea of the severity of the climate they live in. It would be good to have an assessment how well EV batteries will do in your climate before making a purchase.


Seattle Temperature Profile

Image


Minneapolis Temperature Profile

Image



you are right, i did miss the post and the charts you have provided are exactly what is needed

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44,598 miles on 2011 LEAF (retired) 2013 LEAF;14,388 miles. Ah; 64.24-66.39, Hx; 97.11-102.35% kwh 22.0 @70% estimate; 127,105 miles
Sep 2014 Drive Stats. Corolla;213 miles, $19.20, LEAF;2032 miles $44.78
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PostPosted: Mon Aug 13, 2012 3:02 pm 
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DaveinOlyWA wrote:
you are right, i did miss the post and the charts you have provided are exactly what is needed

Oh, great to hear! I shared the underlying spreadsheet, if you were interested in more detail.

Note that the temperature distribution percentages are not accurate. I wonder how lukati got his numbers from that site, I only found a fairly time-consuming method of extracting that info from the image directly. Ideally, we would have this data available in a tabulated form and properly dated as well.

TonyWilliams wrote:
If I were the Nissan legal team, I'd start polishing my defense based on this !!!!

Ha! Who says that they are not? ;-)

Should they invest any time into this, I hope that we will get a chart outlining the severity of climates in all major metropolitan areas in the US. That and the relative change from 2010, when Nissan was apparently conducting the bulk of their hot weather testing. Image


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PostPosted: Mon Aug 13, 2012 3:09 pm 
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just finished an experimental charge (we have soooo little opportunity for any heat related experiments here...) in an attempt to see the magnitude of adjustments possible due to heat. a temporary change in work schedule also helped a lot as well

viewtopic.php?p=220273#p220273

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Sep 2014 Drive Stats. Corolla;213 miles, $19.20, LEAF;2032 miles $44.78
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PostPosted: Mon Aug 13, 2012 3:19 pm 
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DaveinOlyWA wrote:
just finished an experimental charge (we have soooo little opportunity for any heat related experiments here...) in an attempt to see the magnitude of adjustments possible due to heat. a temporary change in work schedule also helped a lot as well

viewtopic.php?p=220273#p220273

Hm, I was getting 266 couple of weeks ago at 14K miles. I loaned out my Gid meter, but I hope to get a fresh reading this week.


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PostPosted: Mon Aug 13, 2012 3:30 pm 
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surfingslovak wrote:
DaveinOlyWA wrote:
just finished an experimental charge (we have soooo little opportunity for any heat related experiments here...) in an attempt to see the magnitude of adjustments possible due to heat. a temporary change in work schedule also helped a lot as well

viewtopic.php?p=220273#p220273

Hmm, I was getting 266 couple of weeks ago. I loaned out my Gid meter, but I hope to get a fresh reading this week.


ya, i have had 8 GID readings all 275 or 276 and one 277. all those charges at night, temps upper 50's to mid 60's and 5 TBs.

this time, i parked car in garage with door open knowing the Sun would shine on back of car. left temp probe sitting under car with temp gauge (has inside/outside gauge) on side of car protected from Sun 36 inches off the ground. temps between two were either same or a degree apart. parked car this morning, temps was 22C but as soon as Sun came over the trees, temps went to 29C rapidly before settling at 31C for the last hour or so. LEAF did have 6 TBs so guessing pack had to be in the mid 80's or so

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Sep 2014 Drive Stats. Corolla;213 miles, $19.20, LEAF;2032 miles $44.78
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PostPosted: Mon Aug 13, 2012 3:34 pm 
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surfingslovak wrote:
Note that the temperature distribution percentages are not accurate. I wonder how lukati got his numbers from that site, I only found a fairly time-consuming method of extracting that info from the image directly. Ideally, we would have this data available in a tabulated form and properly dated as well.

I got the percentages the old-fashioned way: integration through weighing! I magnified the chart and printed it out, then cut the respective temperature bands out and measured their weight on a high-precision (0.0001g) balance. Not the kind of thing you want to do for dozens of locations. ;)

What we need are temperature-frequency tables for different locations. NOAA has that kind of information, but they make you pay for it. The only free such information I have been able to find was specific for a single state. http://www.cemp.dri.edu/cgi-bin/cemp_st ... ul&prod=12


Last edited by lukati on Mon Aug 13, 2012 3:38 pm, edited 1 time in total.

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PostPosted: Mon Aug 13, 2012 3:37 pm 
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lukati wrote:
I got the percentages the old-fashioned way: integration through weighing! I magnified the chart and printed it out, then cut the respective temperature bands out and measured their weight on a high-precision (0.0001g) balance. Not the kind of thing you want to do for dozens of locations. ;)

Ha, nice! I used Photoshop to separate temperature bands by color and ... to count pixels ;-)

lukati wrote:
What we need are temperature-frequency tables for different locations. NOAA has that kind of information, but they make you pay for it. The only free such information I have been able to find was specific for a single location. http://www.cemp.dri.edu/cgi-bin/cemp_st ... ul&prod=12

That's really cool! I worked on mobile weather apps in the past, we used to have custom data feeds from several vendors. I will see if I can get anything.


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PostPosted: Mon Aug 13, 2012 3:50 pm 
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lukati wrote:
...The temperature resolution is quite poor. The temperature bands are frigid (<15F), freezing (15F-32F), cold (32F-50F), cool (50F-65F), comfortable (65F-75F), warm (75F-85F), hot (85F-100F), and sweltering (>100F). For all bands I took the average temperature in the band and I assumed 10F for frigid and 105F for sweltering. ...


If my experience with Tempe residents is any gauge,
110 = "warm"
115 = "hot"

I'm not sure they would ever admit to "sweltering". :lol:

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PostPosted: Mon Aug 13, 2012 3:54 pm 
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Nubo wrote:
lukati wrote:
...The temperature resolution is quite poor. The temperature bands are frigid (<15F), freezing (15F-32F), cold (32F-50F), cool (50F-65F), comfortable (65F-75F), warm (75F-85F), hot (85F-100F), and sweltering (>100F). For all bands I took the average temperature in the band and I assumed 10F for frigid and 105F for sweltering. ...


If my experience with Tempe residents is any gauge,
110 = "warm"
115 = "hot"

I'm not sure they would ever admit to "sweltering". :lol:


the gauge was made when 110 was unusual. those days are long gone

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Sep 2014 Drive Stats. Corolla;213 miles, $19.20, LEAF;2032 miles $44.78
My Blog; http://daveinolywa.blogspot.com


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PostPosted: Mon Aug 13, 2012 4:10 pm 
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WetEV wrote:
...There was an excess of optimism, there is now an excess of pessimism. ...


Your post was well-thought and I hope you're right on this particular point.

Trouble is, this is exactly the worst aspect of the car to be having trouble with, as it represents the biggest area of distrust by the consumer. "What if the $15K battery dies early"... because in normal practice, that is usually what happens with consumer rechargeable battery packs. They die early deaths.

I'd read the article about lack of a TMS. I gave Nissan the benefit of the doubt on that one. But then the lack of warranty was an early red flag. At the dealer when asked about buying or leasing, that lack of warranty popped into my head and I chose to lease. "Trust but verify" :)

The worrisome aspect at this juncture is that the reported degradations are SO much worse than Nissan predicted, it makes one wonder just how bad it might get -- even in more temperate locales. And at this point I'm not inclined to give Nissan the benefit of the doubt in regards to degradation "flattening out".

Unfortunately Nissan is quickly losing the ambassadorship of the enthusiastic early-adopters.

I think they really need to step out in front of this in a big way, even if they don't yet have all the answers. And not a memo full of disclaimers and spin, but forthright statements and a major unwavering show of commitment, such as a retro-active warranty.

The clock is ticking.

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