HVB Degradation

[murphy]

You can enter the time of day that you want charging to start in the car.  It's a single entry with no ability to specify day of the week.  It doesn't clear out automatically so once entered the car will start charging at that time every day if it is plugged in.

 

There are 3rd party applications that use an api that was reverse engineered from the car.  I don't know what their capabilities are.  Tesla can change the api at any time.

[larryh]

This morning, I set the timer to charge the car at 3:45 am rather than 3:00 am.  I unplugged the charger before charging completed at 84% SOC.  The plot below shows the difference in estimated battery lifetime between last week and today.  The difference was less than expected for two reasons:  the high temperature for today and yesterday was 90 F vs. 80 F last week, and I used less energy for the commute to work today than last week so the SOC was higher than it would otherwise have been.  Last week the estimated battery lifetime for my commute to work was 11.3 years.  Today it is 13.6 years.  So by charging 45 minutes later and only charging to 84% rather than 97%, the estimated lifetime of the battery increases by 2.3 years.  It would have been more if it was not 10 F degrees warmer this week than last.  

 

Note that the blue curve (lifetime estimate for today) is mostly above the red curve (lifetime estimate from last week).  It starts out below at time 5:00 pm (yesterday) because the battery was warmer at 107 F vs. 84 F last week.  I charged and drove the car an additional 12 miles after work yesterday which warmed up the battery.  The battery cooled down to 88 F by 3:45 am this morning when charging began.  Charging warmed the battery to 90 F.  The commute to work warmed it further to 93.  During the day, it only cooled down to 91 by 4:00 pm.  So the battery was a little warmer than last week.  The SOC of the battery while parked at work was 63% and after my commute home it is now at 38%.  So both of those numbers are lower than last week.  The lower SOC more than offsets the higher temperatures with respect to battery lifetime.  

 

 

Edited July 7, 2016 at 12:41 AM by larryh

[rbort]

Good idea Larry, that seems to be working well for you!

 

-=>Raja.