Ok, I admit I stole that line from somewhere... but an event of monstrous proportions happened that day regarding my LEAF and the aim of this entry is to get to the bottom of the issue. If you recall my April 2018 driving log, I was well on my way to an acceptable level of degradation (less than 3% over 3 years or 1% per 5,000 miles) on my nearly new 40 kwh LEAF until... well the morning of April 12th when I woke up to this.
Overnight, I lost a chunk of battery that normally would have taken me 7000 miles to lose using the same trend line that matches the rest of my 5600 mile LEAF life! With this humongous overnight drop, I have still only lost 1.43% so far. This despite several multiple QC days, baking the pack to 120º plus, etc. The decline has been daily but very very slow. But remove this one day hiccup and assuming first bar loss at 80% SOH, I was projected to lose my first bar at 167,164.2 miles! This was.... "acceptable" but with the drop (and not enough time passed to overcome the day) my first bar is now slated to drop at 78,321.7 miles.
Below is two graphs charting stats over time and one for miles. As you can see (ignoring Hx which has simply gone off the charts) the trend lines are nearly flat minus the one day. Notice the dip in SOH around 2000 miles? That was a SW change to recalculate SOH on LEAF Spy that did not work out so was returned to the previous method. I have to think the previous method was the same used by hundreds of LEAFers over the years. Data that has all but been proven to accurately reflect the health and capacity of the LEAF battery pack.
To The Logs!
Well the first thing to do was examine logs from April 11th and 12th to see if anything stood out. Did I bake it once too many times? Did I hit a new temperature high? Would the effects of such actions manifest themselves immediately or would they take a few days? It was these questions I hoped to shed some light on.
The day seemed normal. As always, I record LEAF Spy stats daily first thing in the morning before doing any driving.