WetEV said:
jlsoaz said:
WetEV said:
[....]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.
So, grabbing a few minutes to continue the discussion:
the document you cited:
https://www.nrel.gov/docs/fy15osti/63531.pdf
Will Your Battery Survive a World With Fast Chargers?
Published 04/14/2015
- It looks like figure 11 illustrates that in Seattle, there is little battery capacity saved, or projected to be saved (are they projecting 10 years, or do they have 10 years' of empirical data?) with their versions of passive and active cooling and with DCFC being the issue causing hot temperatures and so standing in for high ambient temperatures. Indeed, this point seems worth mulling over.
- There is this statement which I think needs to be heeded:
While the nearly negligible impact of DCFC usage on battery
capacity fade may be surprising to some, it is important to point out
that DCFCs are used quite sparingly in our driver histories. Most
drivers use a DCFC less than once per month (Figure 6), and when
they are utilized, they typically charge the battery less than 60%
(Figure 9). Further, recent tests where DCFCs are used twice per day
to charge Nissan LEAFs driving in Phoenix have shown that the
difference in capacity loss due to fast charger use (as compared to an
otherwise identical case using Level 2 charging) after 50,000 miles of
driving is less than 3% [31].
To me, this casts some doubt on whether this was a really valid test of DCFC, but still, I don't want to pooh-pooh the value of the link. Hopefully over time we can gather quite a few others and out of this a modern understanding will emerge that is closer to helping us understand the choices available to 2019 automakers.
On the old Leaf links that were provided in other parts of the thread, I do think it sounds like some good understanding was achieved during the early days of study and cooperation between drivers and automaker-engineers and others, to understand what was going on with the Gen1 and some subsequent Leafs, but this understanding seems to have been more focused on just the Leafs. Ultimately what I think is needed is more (much more) along the lines of what you've provided here, which compares various approaches, including liquid cooling, and gets at the key questions around what are the benefits and what are the drawbacks of the cooling, in different geographies, use-cases, etc.
On Seattle versus "upstate NY" (with further clarification that was offered in this case, I think Albany/Saratoga Springs area)
- I am not very experienced with weather and climate data, but even just a glance shows that there is some (what seems to me) decent-sized variance in all-time summer monthly record highs among different towns, and between those towns and Seattle.
- maybe it's too far out into the weeds, but I'm wondering if high average humidity might actually help (perhaps in a small way) passive air cooling.
A goal here for me (
both for personal buying but also for industry analysis) is to understand, going into gen3 and so-on, whether, or to what extent, I think it might be a flat-out mistake for an automaker to offer passive or active air-cooling, and to understand this, part of the matter is to compare with liquid cooling (the link you provided does this, somewhat, but some of the other links provided elsewhereI'm not so sure).
As discussed, it's possible to argue that it's not a flat-out mistake but simply a matter of serving different markets and customer needs. One of several reasons I cringe when I see this argument is that I think an important principle in the vehicle business in North America as it plays out is that once a vehicle is let loose in the wild, it is quite possibly going to be subjected to all manner of conditions, even just on a very occasional long trip to another set of climate conditions, or in the hands of a 2nd or 3rd or 4th owner. While one can debate the wisdom of over-engineering a vehicle (and dramatically bumping the up-front price) so that it is likely to have great durability no matter what the abuse, I am hypothesizing that it's best to engineer an EV with the idea in mind that ultimately it will probably not always be kept (by owner practices) within a safe-for-the-passively-cooled-battery-longevity set of conditions.
