April 11th, 2018; A Day That Will Live In Infamy

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.

April 11th

The day seemed normal. As always, I record LEAF Spy stats daily first thing in the morning before doing any driving.

FYI; My elevation is closer to 50-90 feet above sea level (No my neighborhood is not flat) . For some reason, GPS works like crap while in garage...

But everything is pretty much as planned. I don't charge to full when I don't need it and the day was normal in that I parked the LEAF overnight at 68% SOC... (Notice I still have the nearly full range of a 30 kwh LEAF?... That is not an accident.  😎)  The battery pack temps are over ambient which means a QC happened on the 10th.  Normally at that time of year, pack temps would be in the low 60's. 

I then stopped for a QC @ 30% SOC  (152 GIDs) hitting 120 amps pack temps at start;  73.8/69.6/65.5.  Charged to 69.4% (351 GIDs) pack temps;  100.0/97.9/90.6.  

Drove a little bit then QC'd again starting SOC; 64.2% (324 GIDs) starting batt temps; 99.8/96.8/89.6

hitting 83 amps.   Ending;  91.9% SOC, 464 GIDs,  Batt temps; 106.0/102.7/94.2. 

Eventually arrived home with 79.9 % SOC, 404 GIDs,  Batt temps; 103.8/100.0/90.6.  Ending ahr; 114.3086,  SOH; 99.02, Hx; 115.25. SOC was higher than my preference but canceled plans for later that day was the reason otherwise the 2nd QC would have been quite unnecessary. 

April 12th.

First thing I realize its one of those "days" where LEAF Spy is only running a bit in the morning and for QC sessions.  So there is a HUGE gap in time and...well, yeah we already know what that means. What we were looking for happened during that blackout period. 

So I leave home at 5 AM and stop to charge at 5 PM.  Notice pack temps have cooled considerably. Guessing near ambient which means parked somewhere probably all day in the shade!  The log was ended before I got home but the single QC of the day did little to heat the pack. 

But the damage was done. The new baseline was 98.43 % SOH.  This I had to accept. 

The Horizon

All is lost!!... well, actually that might not be completely accurate.  The massive drop in battery health has hardly put my pack on the DL.  What it did do is;

**Failed to make me "QC adverse" since I have quick charged 11 times in the 29 days that have passed. 

** Failed to make me "Heat Shy" since I did journey to Ellensburg in Central Washington a trip of 353.2 miles where the afternoon temps hit the high 80's.  May not seem hot to most but in full Sun (required due to incompatible QCs of Aerovironment forcing me to L2 for several hours) it was baking.  OAT registered 93º on return to car after basking in hum of Arby's AC.  And my sprint to Tacoma from North Bend did cause a near record high of 121.5º batt temp. 

Now extrapolating 29 days of data into a 100,000 mile projection is more than a bit crazy BUT... I got used to being called that so... 

Since "The Day" I have traveled 1080.1 miles losing .18 ahr, .15% SOH while gaining Hx (as usual) This puts my new "Bar Retirement Day" at 106,280.4 miles.  Again, this will be acceptable to me realizing this puts me a few miles over the range of a new 30 kwh LEAF.

BUT...

This is somewhat disappointing as it likely means I will miss my chance of getting a free warranty replacement of a new improved battery pack a few years down the line.  

I knew this car wasn't perfect.