How disappointed should I be that Nissan did not include liquid battery cooling on the Leaf E-Plus?

[SageBrush]

I don't know why, but it is fairly typical for Tesla packs to lose ~ 5% of capacity in the first year and then for loss per year to taper to a low value thereafter. If this behaviour extends to other Li-X chemistries Leftie my have less to worry about than he projects.

 

[jlsoaz]

The direction Nissan is taking now seems how make a lower resistance battery that does not get as hot.

Interesting, thx. This would seem to underscore the importance of keeping an open mind to the role played by chemistry and pack architecture.

I wonder, do we have a figure for the approximate added manufacturer cost per vehicle for a liquid thermal management system? Is it really that high? Granted, there are other disadvantages than cost (weight, complexity, possible safety concerns) but it might be useful to have a realistic number (or range) to pencil in.

 

[SageBrush]

LEAF with passive cooling works better for me than a car with active cooling running its battery down while parked for extended time without being plugged in.

I must have read that 100 times if not a thousand, but always from one person -- you. I'm sure Nissan appreciates your business and support but they probably want a few more customers.

Your broken record did make me wonder though what the vampire drain would be on my Model 3 if I disconnected the 12v.

 

[jlsoaz]

[....]I note that you are in a climate where liquid cooling wouldn't make any measurable difference in battery life.

Hi - I'm not sure where in upstate NY that poster is from but may I ask what are you basing this sort of claim on? Is there any empirical data .... ideally across different EV manufacturers, chemistries and pack architectures...that you know of on these matters?

Does the data you are citing or your own research take into account driver practices or the combination of driver practices and occasional weather extremes?

I've posted the one piece of robust empirical data I can think of which is from the 2012-2013 PluginAmerica study papers by Tom Saxton. There must be more out there, but offhand I don't know where it is.

 

[jlsoaz]

LEAF with passive cooling works better for me than a car with active cooling running its battery down while parked for extended time without being plugged in.

I must have read that 100 times if not a thousand, but always from one person -- you. I'm sure Nissan appreciates your business and support but they probably want a few more customers.

Your broken record did make me wonder though what the vampire drain would be on my Model 3 if I disconnected the 12v.

I'm not that familiar with the people or recent posts on this board, but yes, GerryAZ's point of view is in the minority compared to what I've heard from a few Phoenix drivers... the level of distress and anger of some drivers, over the value they lost with their purchase of some of the early Leafs, was quite strong. Later on, not that he's representative of everyone, but I've heard comments from the President of the Phoenix EV Association focusing as well on the advantages of liquid cooling, in his opinion, for what they see over there.

With that being said, GerryAZ now has me wondering about which battery gets run down. Maybe this speaks to the point of the challenge of keeping the vehicle plugged in, where possible.

 

[SageBrush]

With that being said, GerryAZ now has me wondering about which battery gets run down.

He was talking about the traction battery, as was I. The thing is, the 12V runs the electronics that run the TMS in most EVs. Thus my question about disconnecting the 12V. In case you are wondering, the 12V does not run out of juice in a modern EV because it is replenished by the traction battery.

 

[jlsoaz]

With that being said, GerryAZ now has me wondering about which battery gets run down.

He was talking about the traction battery, as was I. The thing is, the 12V runs the electronics that run the TMS in most EVs. Thus my question about disconnecting the 12V. In case you are wondering, the 12V does not run out of juice in a modern EV because it is replenished by the traction battery.

Thanks, this clears up my understanding of what you were saying.

It may be more un-related than might appear at first glance, but the 12 Volt battery in my 2012 leased Leaf SL and the 2013 Volt have both needed replacing. The Leaf battery came out during a routine scheduled maintenance when the dealer thought it would be a good idea. The 2013 battery died when I left the blinking lights on too long near a roadside issue. In both cases I just thought it was interesting to be reminded that we have not left lead-acid behind yet, and that Arizona is generally hard on 12V batteries.

 

[SageBrush]

With that being said, GerryAZ now has me wondering about which battery gets run down.

He was talking about the traction battery, as was I. The thing is, the 12V runs the electronics that run the TMS in most EVs. Thus my question about disconnecting the 12V. In case you are wondering, the 12V does not run out of juice in a modern EV because it is replenished by the traction battery.

Thanks, this clears up my understanding of what you were saying.

It may be more un-related than might appear at first glance, but the 12 Volt battery in my 2012 leased Leaf SL and the 2013 Volt have both needed replacing. The Leaf battery came out during a routine scheduled maintenance when the dealer thought it would be a good idea. The 2013 battery died when I left the blinking lights on too long near a roadside issue. In both cases I just thought it was interesting to be reminded that we have not left lead-acid behind yet, and that Arizona is generally hard on 12V batteries.

The early LEAFs had a problematic design decision that let the 12V discharge when the car was connected to an EVSE but not actively charging. It lead to premature aging of the 12V. Some generations of Tesla also 'feature' short lived 12V batteries due to deep discharging episodes under some conditions. This is why I prefixed my earlier comment by saying modern EVs use the traction battery to protect the 12V

 

[SageBrush]

I've posted the one piece of robust empirical data I can think of which is from the 2012-2013 PluginAmerica study papers by Tom Saxton. There must be more out there, but offhand I don't know where it is.

You also posted a better link
http://www.electricvehiclewiki.com/wiki/battery-capacity-loss/#Factors_Affecting_Battery_Capacity_Loss
Look at the battery aging model sub-section.

Note that the only exponential term is the Arrhenius Equation. If that bit of math is outside of your toolbox then just accept that deviations above the norm are a lot more important than the mean for the climates we are discussing.

 

[WetEV]

[....]I note that you are in a climate where liquid cooling wouldn't make any measurable difference in battery life.

Hi - I'm not sure where in upstate NY that poster is from but may I ask what are you basing this sort of claim on? Is there any empirical data .... ideally across different EV manufacturers, chemistries and pack architectures...that you know of on these matters?

Does the data you are citing or your own research take into account driver practices or the combination of driver practices and occasional weather extremes?

I've posted the one piece of robust empirical data I can think of which is from the 2012-2013 PluginAmerica study papers by Tom Saxton. There must be more out there, but offhand I don't know where it is.

There are journal papers discussing the topic of the potential gains from active cooling in different climate including a broad range of possible driver practices, and I should and have not acknowledged them as sources. It has been almost a decade since I was reading such journal articles, and I'm not sure I can find the exact sources I've read. Likely far more in depth than you want. Likely behind paywalls as well. Lots of new stuff as well:

Might start with this: https://www.nrel.gov/docs/fy15osti/63531.pdf see figure 11.

 

[Tsiah]

What would you gain with a TMS?

How many hot days per year do you do a QC or 2? What outside temperature? What battery temperatures do you see? Do you have a set of LeafSpy logs you could reference or share to answer questions?


Salt Lake City is hot in the summer, and without any QCs would gain about 10% battery life with a TMS. I've added it to

http://www.mynissanleaf.com/viewtopic.php?f=17&t=27677&p=547072#p547072

The ability to QC without going "holy ****, my battery is 116*F!" ... It'll get over 100*F in the winter if you drive 80 miles, QC and drive another 80.

I don't think it logs temperature, but I'll look in the logs and see. Unfortunately the logs didn't move from my old phone so I only have back to a couple months ago.
My assumption that I wouldn't already be down to 91% SOH could be wrong... I'm really hoping I don't lose another 10% this summer but I'll work on tracking miles/temperature/SOH and see what happens.

 

[WetEV]

It'll get over 100*F in the winter if you drive 80 miles, QC and drive another 80.

Looking back at my logs, I had a 160 mile trip in my 2014 in early January. Mostly freeway. Three QCs. Peak battery temperature of 90F. Outside temperature in the mid 40F range.

LeafSpy logs the battery temperatures and ambient temperature.

My assumption that I wouldn't already be down to 91% SOH could be wrong... I'm really hoping I don't lose another 10% this summer but I'll work on tracking miles/temperature/SOH and see what happens.

First capacity loss to about 5% is usually faster, so hopefully you do better than that.

How often do you DCQC?

 

[jlsoaz]

I've posted the one piece of robust empirical data I can think of which is from the 2012-2013 PluginAmerica study papers by Tom Saxton. There must be more out there, but offhand I don't know where it is.

You also posted a better link
http://www.electricvehiclewiki.com/wiki/battery-capacity-loss/#Factors_Affecting_Battery_Capacity_Loss
Look at the battery aging model sub-section.

Note that the only exponential term is the Arrhenius Equation. If that bit of math is outside of your toolbox then just accept that deviations above the norm are a lot more important than the mean for the climates we are discussing.

Thanks.

- For this model, I see nothing here about any EVs other than Leafs. Is it somewhere else on the page?
- It's not clear to me if the model takes into account data from Leafs from 2014-2015 onward.
- I've been assuming that attempts to draw an equivalency between locations based on similarity of mean temperatures is an over-simplification at best. Were I investigating I would want to know frequency of spikes in temperature, humidity, etc. I would also want to know, as possible, the impact on the battery life, of just a small number of really bad events (e.g: charging in a direct summer sun for several hours) or with frequent moderately bad things (e.g: parking outdoors with no cover all day at work during the summer).

just to note:
I used to try to point out, and still will if given the chance, that outdoor charging under a direct Arizona sun seems not only a particularly poor idea, but could be addressed by outdoor stations making more of a point of locating where the charging vehicle might have some shade (such as with a building or tree to provide some cover) or, ideally, with a ramada to cover the parking spots where the EVs are charging. This is not asking something than is much different at the gasoline stations I see (many or all seem to have cover for the refueling vehicles), though of course there are many important differences between gasoline charging and public vehicle charging. Building ramadas for public charging installations would cost a lot of course and I'm not suggesting it is always possible, but I am suggesting it be given some priority in at least some cases. When I used to suggest this, often the conversation would be immediately side-tracked and effectively largely ruined by demands that the idea and discussion must include solar at all times. I'm a big fan of solar energy, but the idea here is to zoom in on whether it would do much good to consider a higher percentage of vehicle shade installations when public charging stations are installed in hot climates. The solar discussion may somewhat tie in, but it is not the central point.

 

[SageBrush]

Shade is best but the next best thing is asphalt painted to reflect. I think it is worth about 30F and is much cheaper than building shade.
Tesla EVs do not care but LEAFs sure do.

I make it a habit to NEVER park on black tarmac exposed to direct sunlight. That **** gets up to 150F.
It is also a bad idea to garage a LEAF in the summer unless the space is conditioned due to blocked airflow. I suspect that part of the reason that the Phoenix experience is so poor overall is due to their tendency to garage cars when possible.

 

[jlsoaz]

[....]I note that you are in a climate where liquid cooling wouldn't make any measurable difference in battery life.

Hi - I'm not sure where in upstate NY that poster is from but may I ask what are you basing this sort of claim on? Is there any empirical data .... ideally across different EV manufacturers, chemistries and pack architectures...that you know of on these matters?

Does the data you are citing or your own research take into account driver practices or the combination of driver practices and occasional weather extremes?

I've posted the one piece of robust empirical data I can think of which is from the 2012-2013 PluginAmerica study papers by Tom Saxton. There must be more out there, but offhand I don't know where it is.

There are journal papers discussing the topic of the potential gains from active cooling in different climate including a broad range of possible driver practices, and I should and have not acknowledged them as sources. It has been almost a decade since I was reading such journal articles, and I'm not sure I can find the exact sources I've read. Likely far more in depth than you want. Likely behind paywalls as well. Lots of new stuff as well:

Might start with this: https://www.nrel.gov/docs/fy15osti/63531.pdf see figure 11.

Thanks - just a note here - I don't mean to imply that you or anyone else should do a lot to find documents and links. It's just that I really couldn't figure out where you and one or two others are coming from on some of the claims. So, anyway, please don't feel you have to go to a lot of trouble.

 

[LeftieBiker]

Hi - I'm not sure where in upstate NY that poster is from...

If you mean me, I live in the Upper Hudson valley, roughly between Albany and Saratoga Springs.

 

[cwerdna]

- It's not clear to me if the model takes into account data from Leafs from 2014-2015 onward.

I'm pretty sure it doesn't and was only applicable to the lousy chemistry in '11 and '12 Leafs along with ones built before 4/2013, which we presume are the same.

Electricvehiclewiki has really really revamped their pages but I guess you can compare https://web.archive.org/web/20140714232730/http://electricvehiclewiki.com/Battery_Capacity_Loss#Battery_Aging_Model to http://www.electricvehiclewiki.com/wiki/battery-capacity-loss/.

IIRC, the model (which I frankly haven't not followed in detail since my Leaf seems to have a better chemistry battery as it was built 5/2013 and is still only down 1 bar, with SOH at ~82.xx% to 83.xx% nowadays) was partly based upon TickTock's memory from meeting w/a Nissan engineer in late 2012.

http://www.mynissanleaf.com/viewtopic.php?p=230478#p230478
http://www.mynissanleaf.com/viewtopic.php?p=230478#p230478

Both the current copy and the old archived copy I pointed to have the verbiage "(2011-2012 model years only, since the battery electrolyte was "tweaked" for 2013 Leafs)". And, we know that the chemistry was further improved with the "lizard" battery.

Some notes about the testing Nissan did on what became the "lizard" battery: http://www.mynissanleaf.com/viewtopic.php?p=320754#p320754. http://www.mynissanleaf.com/viewtopic.php?f=4&t=17168&p=374490 is from June 27, 2014.

 

[Nubo]

I do have a question for anyone who may have knowledge of this as to empirical evidence of the extent to which frequency of exposure to hotter conditions tends to increase degradation (and in which chemistries and architectures). That is, if a vehicle spends a portion of its life in an area with average temperatures at what might be called "moderate" levels, but with higher frequency of spikes upward than other areas with similar average levels, then what does the evidence say (depending on the various factors) as to increased degradation?

Here is the answer AGAIN, just for you:
The speed of reactions doubles with every 10C increase in temperature in the range of interest
https://en.wikipedia.org/wiki/Arrhenius_equation

Arrhenius figured it out in the 19th century, around the same time that he realized that CO2 is a greenhouse gas.

It's worth noting that Li-ion batteries are not chemical-reaction batteries but rather diffusion batteries. Some key degradation processes are not strictly chemical: growth of crystal dendrites, metal plating of electrodes, physical breakdown of anode material. These are not simply temperature-mediated but also sensitive to voltage.

The other degradation process (growth of the SEI layer) IS a chemical polymerization process though.

 

[jlsoaz]

Hi - I'm not sure where in upstate NY that poster is from...

If you mean me, I live in the Upper Hudson valley, roughly between Albany and Saratoga Springs.

So, IIRC, there are some spikes into some uncomfortably hot temps, and there is humidity. I don't know if humidity is also a factor for batteries... perhaps it impacts, to varying degrees, efficaciousness of different cooling approaches.

 

[SageBrush]

Hi - I'm not sure where in upstate NY that poster is from...

If you mean me, I live in the Upper Hudson valley, roughly between Albany and Saratoga Springs.

So, IIRC, there are some spikes into some uncomfortably hot temps, and there is humidity. I don't know if humidity is also a factor for batteries... perhaps it impacts, to varying degrees, efficaciousness of different cooling approaches.

Humans care because they use evaporation to cool down. Radiators, heat pumps and batteries use conduction and convection, none of which are affected by humidity.