HarmLessSolutions:

 

This owner's well monitored case study is interesting for a couple of reasons.

 

Firstly he is managing to maintain a steady SoH by his charging strategy and minimal distances travelled, which while possible in his situation is probably not practical usage for most Leaf owners.

 

https://batteryuniversity.com/article/bu-702-how-to-store-batteries

At 40% SOC battery voltage should be around 3.82V per cell. What I'm seeing, it would be closer to 50% SOC at 3.92V per cell. Storing at 3.7V for maximum longevity would be about 30% SOC. For me there are practical implications to reducing the storage SOC in my routine. The climate timer works if the battery SOC is 80% or over and the car is plugged in, so reducing the final SOC before departing for work in the morning would effectively negate using the climate timer. This is a bit of free cabin heat and demisting in winter (comes from the wall outlet rather than the battery).

Two main options for amending my charging routine come to mind.

1) Continuing to charge to 80% before departing for work. Car would sit around at work at about 60% SOC for 8 hours. I use about 20% each way mid summer. After reaching home the car would be around or below 40% SOC. Toping up to 40% with a short charge when required. Then use the charge timer to top the car off to 80% just before departing for work. Pluses are climate timer would still do its thing, routine is potentially simplified. Drawback is over 2000hrs per year sitting around at about 60% SOC (currently about 7500hrs/year, 8760/year total).

2) Charge to 60% before departing for work. Car would sit around at work at about 40% SOC. After reaching home the car would be at or below 20% SOC. An approximately 2 hour charge would top the car up to 40%. Then the charge timer would charge the car to 60% just before I depart for work. Drawbacks for this are the loss of the climate timer, and reduced ability to run errands after work. Under this routine the car would spend about 1200hrs per year not at but within 20% of its chosen storage SOC. The other 7500 hours per year it would be at its chosen storage SOC.

I wonder if the owner in the case study kept his car in a climate controlled garage. I see quite a lot of variation in the SOH Summer to Winter but my car sees normal ambient temperature fluctuations.