Insane + Tesla Battery Preheat

Tesla app battery preheat icon
Note: This is another Tesla-specific essay related to battery preheating in the pre-Ludicrous performance models.

In my recent winter road trip essay, I recommend preheating the cabin while still being plugged in, which is one of the more useful features you often see recommended to maximize winter range.  The one feature I didn't remember to try out on that trip, but did on a subsequent trip was a battery preheat "hack" specific to the pre-Ludicrous Tesla P models that have the "Insane" acceleration feature.  All others can tune out at this point other than to stress that battery temperature has an effect on range.

If you prefer a video overview, jump to this short YouTube video on the topic:  https://youtu.be/mF6LcMYUwcs

Limited braking regeneration (dotted yellow lines)
Even with cabin preheating, the Tesla Model S and X does not preheat the battery by default during cabin preheating unless the battery temperature is extremely low.  The result is that regeneration is limited (see picture) and in some cases, power to the wheels is limited.  However, the car does start preheating the battery on battery power when you start driving, thereby using gobs of energy.

Max Battery Power dialog

Turn On Insane + Max Battery Power

If so equipped, your P-model has Acceleration modes:
  • Chill
  • Sport
  • Insane
  • Insane +
When you engage Insane + on the Driving menu, the car responds with a dialog box asking to turn on "Maximum Battery Power" which heats the battery using the onboard electric battery heater, lowers the battery impedance and gives you just a bit more power for hard launches.   The process takes over an hour in some cases which the screen will indicate.

I find this much more useful as a battery heater on a cold-soaked battery.  So here's the procedure I follow:
  • Charge the car overnight to my intended max state of charge, normally 90% on road trips.
  • Go to the car (unfortunately you can't do this from the app) about 30-45 minutes before departure.
  • From the main menu, select Driving -> Acceleration -> Insane+.
  • One the next dialog box, engage the Maximum Battery Power.
  • Go back inside and get warm for about 30 minutes, get some coffee, etc.
  • When you return to the car, select Driving -> Acceleration -> Sport and battery heating will be turned off.  
  • I'm reluctant to let the heater go for more than 1 hour since general wisdom indicates that hot batteries lead to early degradation.
If you open your app to the Climate screen, you'll se a small red battery icon with a snowflake inside to indicate heating is active.  

After this procedure I found that the energy use was in line with normal winter use (around 350 Wh/mile) rather than 400-500 Wh/mile and the dotted regeneration limitation was gone right from the start.

What's Your Take?

I've never heard anyone tell me that this is bad for the battery since I believe it's the same heater that gets activated when you start driving.  I'm wondering why Tesla doesn't activate this as a feature for all Tesla Models with active battery heating.


Resources:

If you are in the market for a Tesla Model S, Model X, or Model 3, Tesla has reestablished its referral program.  Feel free to use my referral code to get 5,000 miles of free Supercharging (at the time of this publishing) for your Tesla:  http://ts.la/karl5062

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