I have two things to report about my SV+ battery -- one which I interpreted to be good news, one bad news.
First, the bad news
I recently took my SV+ on a 290 mile trip from the NYC area to the DC suburbs. The trip down was easy and uneventful. Four days later, the day before I was to drive back to NY, I decided to check out one of the new 100 kW EVGo stations in northern VA (I was staying with family with no charging options other than L1 and wasn't going to get to 100% SOC by the following morning without a DCFC). I charged for about 30 minutes and was impressed to see that until about 60% SOC the SV+ was charging at around 70 kW. This was at about 3 PM. However, the following morning, we left for NY. Ambient temps were in the 50s and 60s and it was raining slightly. The battery temp display on the dash was at the exact mid point when we left. We drove 165 miles, averaging about 68 mph, to an EA station in southern NJ. We charged there for about 40 minutes at around 2 PM. But here's the thing: when we were done charging, the battery temp display had shot up to just one bar shy of the red zone. So why is this bad news? Well, if driving 165 miles in 50ish degree weather and then fast charging for 40 minutes can cook your battery that much, this simply can't be good for the long term battery degradation of this car. Imagine if it had been 85 degrees outside. Imagine if I'd driven closer to 200 miles. Honestly, I've been itching for EVGo to upgrade all their stations to 100 kW (they're allegedly all prewired for 150 kW), but now, I'm not so sure I want that. When I've driven my Leaf+ 160-180 miles in summer weather and then fast charged at a 50 kW EVGo station, the battery temp display has barely gone up. So it seems that there's a big difference in heat accumulation between charging the Leaf+ at 43 kW average for 30-40 minutes vs charging at 68 kW average for 30-40 minutes. Of course, it's possible that the reason my battery took on so much hear during this 70 kW fast charging session was because of the 70 kW fast charging session done 24 hours before. (Normally, on trips like this, I wouldn't fast charge two days in a row.) But if not, and if using 100 kW chargers adds that much heat consistently to the Leaf+ battery, then I'm just going to stick to 50 kW chargers.
Second, the good news
I just passed the 6 month mark on my Leaf+, though the car itself is a full year old since it has an 11/19 build date. (It's a 2019, but I bought it new for a big discount in early May 2020). Here are my Leaf Spy stats. I took a reading on two consecutive days at different SOCs to see what changes if any there would be:
GIDS: 368 (49.1%)
Remain: 28.5 kWh
Odometer: 5289 miles
GIDS: 612 (81.6%)
Remain: 47.4 kWh
Why is this good news? My understanding is that more than any other factor (miles driven, number of QC's, ambient temps, frequency of time spent at 100% SOC, etc), the biggest driver of measurable SOH reduction in the Leaf during year one is simply time. And my Leaf+ is a year old and has apparently only lost 3.12% of capacity in its first year. Yes, this isn't the whole story, and perhaps those who know more about the implications of my GIDS, Hx, and AHr readings could chime in. And yes, while the car is 12 months old, I've only owned it for 6 months. But my sense is that the dealer neglected this battery in the usual Nissan dealer ways for the first six months of this car's life (one small example: I begged them not to charge it to 100% when I picked it up, and it was at 100% when I picked it up). And yet, SOH reduction is only 3.12%. I'm not sure why. I've definitely been driving less -- in non-pandemic times, the car would have had closer to 9,000 miles on it by now. And I've been pretty meticulous about keeping it as close to 50% SOC as possible. (For example, my wife takes it to work now, and we cycle it between 55% - 45% SOC most of the time, or 60% - 40% SOC when we get "lazy"). But I've taken it on several long distance trips to VA, MA, and NH, fast charging for 30-45 minutes on each trip leg (almost always on 50 kW chargers). During one of these trips, the car was in VA for 3 weeks during the summer where it lived outside at ambient temps in the 80s and 90s all the time. The car's also black and it's not always possible to park it in the shade. Anyway, I'm encouraged by this --- I was expecting a 6-7% drop in SOH after one year. Because if I really did only lose 3.12% this year, and if the biggest drop in SOH is during the first year, then annual SOH loss going forward may even settle down to around 2%, which I would consider pretty respectable.
current: Black 2019 SV Plus with all-weather package (purchased 5/20)
former: Silver 2019 SV with all-weather package (purchased 5/19; traded in 5/20 with 15,000 miles)