Plug In America LEAF Battery Survey

[jlsoaz]

Hi all:

At the Tucson 2013 Plug-In Day I was speaking with a Ford Focus EV dealer and this got me to wondering if there has been any evidence that has come up that the Focus EV or other liquid-cooled (I think it is) EVs are a good alternative for potential Tucson Leaf buyers to consider? That is, is there any data out there yet on degradation in some of these more obscure EVs?

 

[TomT]

I think you will find that virtually any other EV would likely be fine since that all have TMS.

At the Tucson 2013 Plug-In Day I was speaking with a Ford Focus EV dealer and this got me to wondering if there has been any evidence that has come up that the Focus EV or other liquid-cooled (I think it is) EVs are a good alternative for potential Tucson Leaf buyers to consider? That is, is there any data out there yet on degradation in some of these more obscure EVs?

 

[jlsoaz]

Thanks Tom. While it may prove out to be true that PEVs equipped with liquid TMS (and keeping in mind that even within the category of liquid TMS, not all TMS or battery chemistries are the same) help reduce degradation rate better in the tough climates like Tucson, I think what I'm curious about is how we get from making this a working assumption or hypothesis or anecdotal thing to a more proven thing, such as with the harder-to-argue-with data that we see at PIA. I know they have some data on Tesla, so that would be a start, but will be curious to see if they develop data on Focus EV, etc. Maybe there would be a way to keep it at a low resource level but for PIA to set it up so that all PEV drivers are encouraged to participate in the PIA battery ongoing information-gathering.... not just Leafs and Teslas (or maybe this is already somewhat done? Haven't checked there in awhile).

All EVs including the Leaf have some form of Thermal management I think, but as to ones that have liquid cooling, I think it would be somewhat narrower. For example, I don't think the Mitsubishi does. A year or two ago I looked at comparing the Ford Focus EV to the Ford C-Max Energi PHEV in this area and, if I recall correctly, the Energi PHEVs did not have liquid cooling. Someone please correct me if I am wrong.

Of course, between the Leaf and the more aggressive Liquid TMS systems, there may be a question of degree, or more than one approach to TMS.

I think you will find that virtually any other EV would likely be fine since that all have TMS.

At the Tucson 2013 Plug-In Day I was speaking with a Ford Focus EV dealer and this got me to wondering if there has been any evidence that has come up that the Focus EV or other liquid-cooled (I think it is) EVs are a good alternative for potential Tucson Leaf buyers to consider? That is, is there any data out there yet on degradation in some of these more obscure EVs?

 

[Weatherman]

All EVs including the Leaf have some form of Thermal management I think, but as to ones that have liquid cooling, I think it would be somewhat narrower.

Unless something has changed I don't know about, the LEAF has no thermal management of the battery. Anyone in a warm climate, who sees their battery temperature hover in the 90s and low 100s for weeks at a time is, painfully, aware of that.

 

[jlsoaz]

All EVs including the Leaf have some form of Thermal management I think, but as to ones that have liquid cooling, I think it would be somewhat narrower.

Unless something has changed I don't know about, the LEAF has no thermal management of the battery. Anyone in a warm climate, who sees their battery temperature hover in the 90s and low 100s for weeks at a time is, painfully, aware of that.

Hi - I am one of those drivers living in those conditions. IIRC all the Leaf does to moderate the battery to lower temps is to allow air to pass by the battery while driving, though I could be wrong.

I guess I am trying to make the point that, even if many of us consider this to be a very weak form of TMS, and some would argue poor judgment on Nissan's part, it is still (as far as I know) a form of TMS.

Maybe I've got the definition of Thermal Management System wrong but as far as I know the Leaf doesn't lack TMS, ... it lacks active TMS, or (in my view) it lacks good TMS for warmer climates. (I also don't remember what it does or doesn't do in colder climate situations).

IIRC, Andy Palmer went over some of this at the Phoenix Town Hall which is available on video, and he discussed that prior to his work at Nissan, this was an area of engineering in which he had worked. This is not to try to get into a debate as to his answer, only to say that I think there's a Nissan video discussion of this out there, if one of us has time to find the link and the point in the 2 hour video wherein it is discussed.

At the very end, I think Jim Stack also made a suggestion that was in theory taken well by Nissan as to some form of fan, perhaps powered by the solar panel.

 

[TomT]

No, the Leaf battery pack is simply a sealed and pressurized container with some insulation and has no TMS of any kind. It is subject to adopting whatever the ambient temperature is and will ultimately reach that temperature, albeit very slowly due to its significant thermal mass. The only exception is that the later versions with the cold package have a very small electric heater in them that kicks in at exceptionally low temperatures to prevent the battery from freezing.

IIRC all the Leaf does to moderate the battery to lower temps is to allow air to pass by the battery while driving, though I could be wrong.

 

[jlsoaz]

Thanks Tom, I think the disagreement here is not about what the Leaf does and has; rather it is about the definition of TMS.

As far as I know, both the use of insulation and the allowing for air to go by the system while driving amount to passive TMS, i.e., a type of TMS. I have very little knowledge in this area, and will be happy to learn otherwise and stand corrected, if someone could please provide a credible link that discusses the definition of TMS and, specifically, a definition of passive TMS and, if it exists, whether passive TMS is considered a form of TMS in xEVs.

No, the Leaf battery pack is simply a sealed and pressurized container with some insulation and has no TMS of any kind. It is subject to adopting whatever the ambient temperature is and will ultimately reach that temperature, albeit very slowly due to its significant thermal mass. The only exception is that the later versions with the cold package have a very small electric heater in them that kicks in at exceptionally low temperatures to prevent the battery from freezing.

IIRC all the Leaf does to moderate the battery to lower temps is to allow air to pass by the battery while driving, though I could be wrong.

 

[Weatherman]

Maybe the key word is "management"?

When I think of "management", I think of active measures taken to change or maintain something. Except in the most extreme cases, the LEAF's battery temperature is not actively changed or maintained. It's, pretty much, subject to the whims of the environment. If I had a lawn chair out in my backyard, I wouldn't say it has a TMS. I see the LEAF battery the same way.

 

[TomT]

+1!

When I think of "management", I think of active measures taken to change or maintain something. Except in the most extreme cases, the LEAF's battery temperature is not actively changed or maintained. It's, pretty much, subject to the whims of the environment. If I had a lawn chair out in my backyard, I wouldn't say it has a TMS. I see the LEAF battery the same way.

 

[jlsoaz]

Hi - FWIW, some discussion, from Nissan, of different thermal management approaches at 0:25:13-0:28:10 or so,
1:13:30, 1:35:00, particularly the first and second.
http://www.youtube.com/watch?v=uuPQe23vP0Y" onclick="window.open(this.href);return false;
Nissan LEAF Town Hall Meeting - Battery Capacity Reduction & Warranty
Published on Jan 13, 2013

I can't find one or two things that from memory I know are in there. There was a guy in the back who made a good point, I thought, about the temperature of the hot Phoenix pavement and the questionability of using air to cool the battery. Once or twice it seemed that Nissan really might not understand that Phoenix is or can be as hot, or nearly as hot, as nearly any city on Earth.

Taking a look at some of the random mentions on the web of thermal management, some make a distinction that the Leaf lacks active thermal management, and some just say it lacks thermal management. I realize that there are some who will argue that letting the air pass along the battery as the car goes does not amount to any thermal management at all, but I think, having listened to Nissan's points and in any event followed this and that over the years, it seems worthwhile to me to make the distinction between active and passive.

Please note, this does not mean that I have ever agreed with Nissan's decision to go with their cooling approach (or lack of much approach..whether it's called no TMS or passive TMS is a side-matter in my view).

In 2009-2010, it looked to me like an issue waiting to happen and it did happen. I do think they saved themselves some money and kept the vehicle cost down, but we'll see if that was really worth it. There are some indications that the replacement batteries are good stuff. I think, at this point, for my own situation, a replacement battery might ultimately be in order, but I suspect I will be out some money renting gasoline vehicles before the battery gets replaced, due to the eight bars criteria.

+1!

When I think of "management", I think of active measures taken to change or maintain something. Except in the most extreme cases, the LEAF's battery temperature is not actively changed or maintained. It's, pretty much, subject to the whims of the environment. If I had a lawn chair out in my backyard, I wouldn't say it has a TMS. I see the LEAF battery the same way.

 

[jlsoaz]

....
In 2009-2010, it looked to me like an issue waiting to happen and it did happen. I do think they saved themselves some money and kept the vehicle cost down, but we'll see if that was really worth it. There are some indications that the replacement batteries are good stuff. I think, at this point, for my own situation, a replacement battery might ultimately be in order, but I suspect I will be out some money renting gasoline vehicles before the battery gets replaced, due to the eight bars criteria.

I woke up thinking that over the years when I read an article about a Porsche or some other car, they'll make a point of saying the engine is air-cooled or liquid-cooled and occasionally discuss the pros and cons.

We have also run into the Tesla battery fire situation the last couple of days. In reading through the articles, it was a reminder to me that another arguable advantage of Nissan's approach was to reduce the risk of something happening similar to the Volt (I guess part of the issue with the Volt fires involved the liquid coolant after the crash tests). As mentioned, in the end I am not sure I agree with Nissan's approach, but it bears mentioning that the added complexity of liquid cooling seemed, at least momentarily, to be an issue for Chevy (though they seem to have addressed the issue firmly).

 

[dgpcolorado]

...Please note, this does not mean that I have ever agreed with Nissan's decision to go with their cooling approach (or lack of much approach..whether it's called no TMS or passive TMS is a side-matter in my view).

In 2009-2010, it looked to me like an issue waiting to happen and it did happen. I do think they saved themselves some money and kept the vehicle cost down, but we'll see if that was really worth it. There are some indications that the replacement batteries are good stuff. I think, at this point, for my own situation, a replacement battery might ultimately be in order, but I suspect I will be out some money renting gasoline vehicles before the battery gets replaced, due to the eight bars criteria.

My recollection is that Nissan's approach was to use a battery chemistry and design with low resistance that developed less heat in use. This was intended to make it last longer without TMS. We now know how that turned out. I sure hope that they can come up with some sort of heat resistant battery.

So far as passive cooling goes, I have found that if the ambient temperature is 20ºF or lower than the battery temperature, my battery temp falls fairly rapidly while driving even though it would ordinarily heat up if the ambient was close to the battery temp. Blowing cold air across it by driving works quite well and seems to be faster than just leaving the car parked.

 

[cliff]

is there any data out there yet on degradation in some of these more obscure EVs?

Interesting question, I saw a reference to a Volt manual that stated the liquid cooled TMS is only
turned on while driving, or charging. So this could easily mean it is only on 4 hours, and off 20 hours.
The off time could also easily be during the peak heat hours of the day. So how long would that TMS
have to be on to be effective? Can the liquid cooling provide value when not tuned on(absorbs heat)?
So if the Volt TMS does work, I would have to guess that the effective time would be less than 4 hours,
but I also have seen no data on this. This does make me wonder if the liquid cooled TMS effectiveness
is as black and white, as is suggested on this forum.

 

[surfingslovak]

This does make me wonder if the liquid cooled TMS effectiveness
is as black and white, as is suggested on this forum.

Where is that suggested on this forum, and what gives you the reason to interpret that as a consensus view? Also, there is some data available on both TMS energy consumption and operation, as well as pack degradation. Both have been discussed and referenced on this board. That said, I'm not quite clear what these comments have common with the topic of this thread.

 

[Weatherman]

Interesting question, I saw a reference to a Volt manual that stated the liquid cooled TMS is only
turned on while driving, or charging. So this could easily mean it is only on 4 hours, and off 20 hours.

Actually, the TMS is on when the car is on and/or when it's plugged in. It doesn't need to be charging, just plugged in. It's why GM recommends the Volt be plugged in whenever it's idle.

If it isn't possible to plug the car in, fortunately, the battery is very well insulated (vastly more so than the LEAF battery). So, it would take many hours under the hot, summer sun to warm the battery up significantly. If any Volt owner is concerned about this, they can just turn the car on and let the TMS run for 15 or 20 minutes during the middle of the day. That will, effectively, knock the battery temp back down.

 

[jlsoaz]

This does make me wonder if the liquid cooled TMS effectiveness
is as black and white, as is suggested on this forum.

Where is that suggested on this forum, and what gives you the reason to interpret that as a consensus view? Also, there is some data available on both TMS energy consumption and operation, as well as pack degradation. Both have been discussed and referenced on this board. That said, I'm not quite clear what these comments have common with the topic of this thread.

I appreciated that Cliff brought the discussion back to my question(s). Has PIA or someone else gathered useful data on this question of the degree of effectiveness of liquid cooling and other thermal management? Is there a way (beyond piece-by-piece anecdotes) to figure out if liquid TMS is proving out as a solution or partial solution in the situations we see in Tucson and elsewhere?

I think Cliff's comments were not out of line. To respond to your question, I think it has been suggested by one person just within just the last few posts on this thread that liquid TMS is a good response to severe battery degradation situations.

It probably is - I'm just wondering if there is data out there (other than PIA Tesla data?) which helps support this.

As to the relevance to this thread, I personally think it's relevant. I think it's natural in Phoenix and Tucson and other hot climates to try to figure out what the options are (Leaf with newer batteries, Volt, Focus EV, Tesla, etc.) and the pros and cons, and it's easier to do a better job of this with as much good information as we can lay our hands on. PIA has done a service for Leaf drivers, and for Nissan, by allowing us to all to elevate the discussion above anecdotes and anger, harnessing the enthusiasm of early-adopters and allowing us to have a more enlightened and productive discussion with Nissan in a tough situation. I don't mean to imply they have resources to do a battery survey of the rapidly expanding number of EV drivers worldwide, but am wondering if they or others have moved to gather a bit of data that might help buttress or challenge some of the thinking around a question like "if I am buying an EV in a place like Tucson, should I give a bit of extra weight to the idea of getting a Focus EV because of the liquid TMS?"

 

[tomsax]

I am interested in doing Plug In America surveys for other EVs. I just have two criteria for considering a new vehicle to survey:

- It must be a full production vehicle, available for sale nationwide, without an artificial production limit. I can't afford to spend time setting up surveys for compliance cars.

- It must have instrumentation that shows the driver the battery capacity. This could be battery capacity in kWh or Ah. The Leaf's capacity bars barely qualify, but Gary Gidding's SOC meter, LeafSpy, etc. are much better. A GOM doesn't count, nor does a percent charge level if 100% changes meaning as the battery capacity degrades.

It would be great to do a Volt survey, but it lacks the required instrumentation.

The same is true of the Ford Focus EV. There is an aftermarket SOC meter for the Focus, but so far I've only heard from one driver who is using it.

 

[tomsax]

I have updated the LEAF battery survey to add a couple of things.

First, it now asks for the car's model (S, SV, SL) so we can distinguish between the two battery sizes in the 2016 LEAF.

Second, when you do an update it uses your past reports to reconstruct your Carwings history. That data was always there in the reports, but now it's visible when you fill in an update report. It's handy because Carwings only keeps data for a couple of years. As long as you fill in a survey report after each year ends, you'll be able to maintain a complete driving history which you can view any time by looking at your most recent survey report.

I'm planning to look at the data for a follow-up report in the next couple of months, so now would be a great time to send in a report or update.

If you have submitted a report previously, you can use the update form, otherwise use the survey form.