jwardell
Well-Known Member
- First Name
- Josh
- Joined
- Sep 14, 2021
- Threads
- 1
- Messages
- 212
- Reaction score
- 320
- Location
- Boston
- Website
- www.jwardell.com
- Vehicles
- R1T
- Occupation
- Electrical Engineer
Going on a long drive in subzero temperatures can certainly be surprising if you don't prepare for it.
-Air density is much higher and causes more drag, especially as you drive faster. Ask any pilot.
-Batteries can not be charged at ALL below freezing, and regen is reduced linearly below room temperature. So you will lose regen with a cold battery, or you will waste energy heating it. Precondition the battery before you leave when still plugged in (if Rivian implements this) to help.
-Likewise the battery must be near balmy to achieve high power DC fast charging. You are in for a rude awakening pulling into a fast charger on a very cold day and realizing your 20 minute charge turned into an hour. Tesla eventually added preconditioning when navigating to a supercharger to help this, and I hope Rivian does the same (otherwise, heat things up by driving like hell)
-It takes a *LOT* more energy to heat the cabin from 20 to 70 degrees than cooling from 90 to 70. Especially if it has a resistive cabin heater and not a heat pump.
But... my Model 3 is still the best winter vehicle driven BY FAR... Because most of the time, one tap of my phone 5 minutes before I leave and everything he preheated and ready to go. Also because traction control in EVs is orders of magnitude more reactive than ICE and driving in the snow is effortless and like you're on rails.
Preheat, and just account for 25% less range or drive a bit slower.
-Air density is much higher and causes more drag, especially as you drive faster. Ask any pilot.
-Batteries can not be charged at ALL below freezing, and regen is reduced linearly below room temperature. So you will lose regen with a cold battery, or you will waste energy heating it. Precondition the battery before you leave when still plugged in (if Rivian implements this) to help.
-Likewise the battery must be near balmy to achieve high power DC fast charging. You are in for a rude awakening pulling into a fast charger on a very cold day and realizing your 20 minute charge turned into an hour. Tesla eventually added preconditioning when navigating to a supercharger to help this, and I hope Rivian does the same (otherwise, heat things up by driving like hell)
-It takes a *LOT* more energy to heat the cabin from 20 to 70 degrees than cooling from 90 to 70. Especially if it has a resistive cabin heater and not a heat pump.
But... my Model 3 is still the best winter vehicle driven BY FAR... Because most of the time, one tap of my phone 5 minutes before I leave and everything he preheated and ready to go. Also because traction control in EVs is orders of magnitude more reactive than ICE and driving in the snow is effortless and like you're on rails.
Preheat, and just account for 25% less range or drive a bit slower.
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