Stoaty said:
As far as I can tell, the effects of ambient temperature on battery pack temperature are far greater than the effects of charging, at least when going to environments of 90 degrees F. or more with the Leaf parked in the sun.
Yes, that seems to be a reasonable assumption. However, Nissan has gone on record saying that their batteries don't require a TMS. Well, at least not in the US market, and that they were considering active cooling for markets such as Dubai.
While it's reasonable to assume that it's safe to charge the Leaf to 100% each and every day and park it in an unshaded spot in a hot parking lot, Nissan does not tell us what a more careful approach would yield in relative terms. If an average pack degraded 20% after five years of careless use, and 15% after 60 months of babying, then perhaps the extra effort was not worth it. Obviously, it should be up to the owner to decide. And what if the difference was more significant? Unfortunately, Nissan is probably not going to tell us, and will continue to hide behind references to proprietary battery technology.
About the report we discussed earlier, I wanted to add that although the cells under test had the same basic chemistry, they were not optimized for EV use. I found a
spec sheet for LG Chem's E1 cell. It's from 2004 and it's very likely that the cells they are using in the Volt have evolved quite a bit since then. Likewise, I imagine that the AESC cells the Leaf is using are similar in their characteristics. And again, we are only doing this comparison, because AESC does not tell us anything about cycle and calendar life of their cells.
The E1 cells have about ten times better cycle life than the ones we looked at earlier. They were cycled in a wider range too: 3.0 to 4.2V versus 3.4 to 4.2V. The capacity loss was about 15% after 500 cycles versus 15% after 60 cycles. Although LG Chem does not say anything about calendar life, it's likely that they optimized that characteristic too and E1 performed much better than the cells examined by the University of Michigan in their report.
I'm only saying this to underscore that anything we do, from charge protocols to storage temperature has only a relative effect on battery life and the pack has already been optimized for EV applications with everything that it entails.