WetEV wrote:Might be rather less than you expect, as the AC might only need to limit temperature in the garage to something like 35C or 100F or something fairly warm. Not standard AC to 72F.
It WOULD be nice to know the magic number... the number of degrees of ambient temperature where it's no longer safe for the battery, whether it's outside in the blazing sun, or outside in the shade, or in a garage. The manual says 120 degrees for 24 hours, but we're not hitting that for a lot of people, yet still the battery capacity losses. We need to know the magic number.
There probably is no "magic number".
There curve of additional deterioration due to battery heat is probably nonlinear, with much higher increased deterioration with a degree of temperature increase, from very high ambient temperatures. this may be why a "minor" increase of summer temperatures in the US Southwest, of ~5 F over historic norms, may have been a major factor in the LEAF lost capacity bar "epidemic" there.
The problem with any active BTM system, whether of only the battery itself, or the entire car, is that it is invariably required to draw energy during summer peak hours, when electricity is far more expensive.
With active cooling, you either need to cycle the battery while parked during mid-day, or provide a plug to use expensive peak grid power, during the daily Summer temperature peak. These costs are in addition to the significant production and maintenance costs of the active cooling system itself.
Nissan apparently believed passive management would be the better option, providing lower costs and more efficient operation overall. Whether Nissan was right or wrong, declining battery prices, battery designs with better high-heat resistance, and increasing grid peak power costs (all likely, IMO) should tend to make the passive option more cost-competitive in the future.
I also want to point out, again , that by extrapolating current of US Southwest temperature trends over the last two years, the same way many have extrapolated Battery bar disappearance on this thread, could also lead to the conclusion that much of this region would be largely uninhabitable by humans during them "expected" lifespan of a 2012 LEAF battery pack.
If I lived in Phoenix, I might be much more worried about my home's future resale value, than my LEAF's...