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PostPosted: Wed Aug 15, 2012 11:13 am 
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surfingslovak wrote:
I agree that not having a TMS highly desirable from an engineering perspective, it simplifies the design a lot.


A simpler, and much less costly engineering perspective would be to limit the LEAF to ambient temperatures below XXX degrees. Problem fixed!!!! That's just not consumer friendly.

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They could make 80% charge standard, as has been often suggested, and either add a fan or leverage the existing hardware to get more air flow around the battery on very hot days.


Even cars that were charged to 80% in Phoenix are losing capacity. Adding a fan to circulate 120-140F asphalt parking lot heat around the battery probably won't be successful (maybe for marginal cases of localized heating).

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PostPosted: Wed Aug 15, 2012 11:28 am 
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TonyWilliams wrote:
A simpler, and much less costly engineering perspective would be to limit the LEAF to ambient temperatures below XXX degrees. Problem fixed!!!! That's just not consumer friendly.

Sure, I understand. What I meant to say is that from a purely engineering point of view, a simple design is desirable. A TMS could be cost prohibitive. Perhaps using a less temperature-sensitive chemistry (lithium titanate) and using forced-air cooling (fan) could be good enough. That seems to be what Honda is doing with the Fit. But to be fair, it could very well be that a car like the Leaf, with the design choices that were made, was not viable in hot climates without a TMS.

TonyWilliams wrote:
Even cars that were charged to 80% in Phoenix are losing capacity. Adding a fan to circulate 120-140F asphalt parking lot heat around the battery probably won't be successful (maybe for marginal cases of localized heating).

Yes, of course, I remember. Charging to 80% won't help address the problem in Phoenix, but it might help improve the longevity of the battery pack across the entire fleet. The average SOC is one of the primary factors driving degradation. That said, our number one problem appears to be temperature-induced capacity loss, and it's apparently ahead of the other factors by an order of magnitude.

Still, it's a cheap fix that could be implemented on a short notice, which was the main reason why I mentioned it. Image


Last edited by surfingslovak on Wed Aug 15, 2012 1:09 pm, edited 2 times in total.

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PostPosted: Wed Aug 15, 2012 11:30 am 
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surfingslovak wrote:
Charging to 80% won't help address the problem in Phoenix, but it might help improve the longevity of the battery pack across the entire fleet.


And you will handle the Honda-esque lawsuits how?

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PostPosted: Wed Aug 15, 2012 11:32 am 
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TonyWilliams wrote:
surfingslovak wrote:
Charging to 80% won't help address the problem in Phoenix, but it might help improve the longevity of the battery pack across the entire fleet.


And you will handle the Honda-esque lawsuits how?

I didn't say that the 80% default would be implemented on existing vehicles, or did I? And even if it was, it's a setting you can override and charge to full. That's not something you could do with the Civic Hybrid. The reason I'm mentioning it at all is simple, this is exactly what Tesla vehicles do: 80% charge is standard and you override it or set a timer if you needed more.


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PostPosted: Wed Aug 15, 2012 11:33 am 
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surfingslovak wrote:
TonyWilliams wrote:
surfingslovak wrote:
Charging to 80% won't help address the problem in Phoenix, but it might help improve the longevity of the battery pack across the entire fleet.


And you will handle the Honda-esque lawsuits how?

I didn't say that the 80% default would be implemented on existing vehicles, or did I? And even if it was, it's a setting you can override and charge to full. That's not something you could do with the Civic Hybrid. The reason I'm mentioning it at all is simple, this is exactly what Tesla vehicles do: 80% charge is standard and you override it or set a timer if you needed more.


Ok, I thought you were retroactively, and permanently making an 80% charge. Got it now.

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PostPosted: Wed Aug 15, 2012 11:56 am 
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[quote="TonyWilliams"
6. Start a battery exchange program. When degradation hits some value, you go to a dealer who has access to a regional battery bank (in climate controlled buildings), who then swaps out your battery while you wait. A nominal fee is charged for the service, but all costs of batteries are borne by Nissan
[/quote]

Well considered list, Tony.

I like choice #6. If the batteries are same technology as the current packs, we'll continue to see degradation in hot areas, but this type of program could mitigate the issue for Nissan for some years, with repeated swaps as necessary. If you think about it, it is similar to a battery lease program, though more expensive for Nissan. I recall that Nissan was seriously considering leasing the batteries and selling the cars. This outcome would be somewhat similar for affected owners.

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PostPosted: Wed Aug 15, 2012 12:07 pm 
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Nissan could easily add a "crude" active cooling system to the Leaf.. all Leafs come with an AC system, divert some of the freon to evaporators bolted to the outside of the battery case and cover the whole thing with an insulation blanket.. perhaps they have to increase the size of the compressor. You can still keep a sealed battery case.


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PostPosted: Wed Aug 15, 2012 12:12 pm 
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surfingslovak wrote:
...
Aside from a different chemistry, perhaps similar to what Honda is using in the Fit, what else could be done in a realistic timeframe? Stop selling the vehicle in certain markets?


Cell chemistry change. Who knows what's in the lab; maybe they are closer than we know.

Barring that, add an effective insulating layer to the pack combined with a forced-air cooling system. Outside air only to be introduced when the ambient temp is below the pack temp. It seems at least possible that this could get the pack as cool as possible at night, and limit thermal absorption of the battery mass during the heat of the day, hot pavement, etc..

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PostPosted: Wed Aug 15, 2012 12:38 pm 
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TonyWilliams wrote:
6. Start a battery exchange program. When degradation hits some value, you go to a dealer who has access to a regional battery bank (in climate controlled buildings), who then swaps out your battery while you wait. A nominal fee is charged for the service, but all costs of batteries are borne by Nissan

7. ????


Hey, i knew you would come around! actually, i dont blame you for being upset but i did not think you were the type of person to assume the worst. i took you as a "it is not "feasible" because no one had the guts to do it yet, so i will show them "how its done" type of guy.

but you have to admit speculation completely based on a worst case scenario has simply gotten out of control. i mean lawsuits? wow. either way, i think you are probably very close here.

i posted this in the "battery lease" thread and granted its a short quote from a long post so could be read a bit out of context but basically its investigating Nissan and 2nd guessing their decisions on active battery management. working in the tech support/customer service field i have noticed an ongoing pattern in emerging technology that is pretty repeatable. companies play their cards real close to the breast so we will never know a tenth of the facts considered when these decisions were made but a few things are obvious. in the decision making room we have 3 entities; engineering, sales and marketing.

marketing has 80% of the say so, engineering about 20% and sales basically gets coffee for the other two. so there is no surprises here. Nissan knew this would happen and marketing made a decision. it was a risk as all marketing decisions are. engineering told them what would happen. they were emphatic in their pleading. Marketing said ok then , can you do "A" by "X". engineering said "no", marketing went to the board and replied "no problem, engineering assured us they are on schedule" and here we are.

if you remember back, it was obvious that marketing had created an ambitious timetable for the LEAF launch that simply could not be met. back in 2009, there was all kinds of announcements touting all kinds of EVs that would be vying for the initial customer. as we all know now, none of that happened. the timetables were either pushed back or the company simply faded away. 19 months later, Nissan still essentially stands alone. so they had much more time then they thought and well, you know.

so playing the roll of "armchair engineer" here is something that i cant really justify since we dont really have a clue as to what the engineers of Nissan really wanted but...

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without #'s on costs, its tough to run a cost analysis but maybe a program that builds in the cost of pack replacements every 3 years for 20-40% of the LEAFs is cheaper than installing active temp controls on 100% of the vehicles especially when a newer chemistry with completely different needs and requirements might be just around the corner.


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PostPosted: Wed Aug 15, 2012 12:41 pm 
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SierraQ wrote:
WetEV wrote:
Depending on temperature profile, driving style and a whole list of other factors, my personal expectation of BEV Li ion battery life without TMS (battery Thermal Management System) over the range of US conditions and drivers is from about 500 to about 4000 full battery cycles to 70% capacity. This is from 37,500 miles to 300,000 miles, based on 75 miles per full battery cycle. A few batteries will be outside this range. I think that this is a very reasonable expectation, and is supported by personal Li ion experience and by journal papers. One might argue this issue at length, and perhaps it should be. I'm just not going to do that now.


I know some people seemed to like this post but I had to sit back and say... really? This is like saying: "Today I predict I will walk between 50 feet and 10 miles." Or, "The sun shall rise sometime between 2AM and noon." While it is most likely true it is also a given and does nothing to help perspective EV owners. Yes, batteries are greatly affected by how much you do or do not abuse them but in this case Nissan promised us the battery was protected and we could not damage it. With such protection eliminating the extreme cases it is absolutely not reasonable to to expect the battery to give out before most cars would be out of their bumper-to-bumper warranty!

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Reality, at least so far, seems to be matching my expectations. While a faster decline in gid count has been seen, it is not clear how much of this is a software issue and how much is a real capacity decrease. It seems to be at least a little of both. I may be a little optimistic, but that's my own personal issue, I don't expect Nissan or anyone else to cover the risks I chose to take. A new technology is a risk. I know that, everyone should know that. I took that risk with my eyes open.


Most technology is new in some fashion so I don't buy this excuse. A company must stand behind their products. There is an expectation that companies do the proper research and testing to ensure that some reasonable level of quality is met. There is an expectation that products can be used for their purpose. The risk we all took is: 1) can we live with a 80ish-mile range vehicle and 2) will the cost of replacing the battery 5-10 years from now be far less than it is today. We did not take a risk that you could not use the car in natural activities for a car--driving it in the rain for example. In fact Nissan bent over backward with ads, examples, and testimonials that the Leaf was just a regular car that happened to be powered by electricity.

This is not to be confused with natural limitations. Driving the Leaf 80MPH will get you far less range than at 60MPH. That was clearly communicated and accepted. Driving in hot weather, however, is a natural activity. If they told us such heat would reduce the battery life from 10 years to 8, I think that is reasonable in the same way that driving in northern states causes more body wear because of the ice and salted roads. But we are seeing 10 years down to potentially 3 if the degradation does not level off.

Quote:
The information needed to make an informed purchase was out there. There was an excess of optimism, there is now an excess of pessimism. There is a point to having a BEV like the Leaf (Li ion with no TMS) in much of the country.


The information was faulty. Nissan was pretty careful not to make any promises on capacity but they did imply that the car would retain 80% after 5-10 years--another overly broad range but far short of the 1-2 years we are seeing. While I agree there is an excess of pessimism and like some I believe Nissan will set this right because they care about their name, I also think much of the loud complaining is justified because a car is a major purchase and one your whole livelihood depends on. People naturally get really upset when things go wrong with something like that.

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Yes, a full court legal press might maximize your payout, and will surely maximize the lawyer's pay. But is that a good thing? If it convinces other car companies to not offer a comparable BEV, is it a bad thing? I guess the answer depends a little on point of view, and on the time period, and what costs you consider.


This idea of not pressuring or punishing Nissan "for the good of the EV movement" is ridiculous. You do not help a person or a cause by coddling their weaknesses. All great successes have had their failures which have helped in the long run. EVs will learn from their failures and grow better as a result. If the worst should happen and Nissan and the Leaf go down in a fiery lawsuit this won't discourage a competing company from making an EV but it will teach them not to repeat the same mistakes. And that is all good.

Is it lawsuit time? Of course not yet. But one should not be afraid of that remedy and we should not be critical of anyone who goes that route. The complaint is legitimate and some kind of restitution is most definitely in order. Hopefully Nissan will recognize this and do the right thing.


Thank you SierraQ, for this post. I couldn't have said it better. ;)

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