It was 9°F at my house and 0°F at work this morning so I knew the ICE would start to provide heat. Since the car was in a 40°F garage all night and the sun was out, I thought I'd try with the heat off so I turned it off as soon as I got in, turned the seat heater on high and turned on the steering wheel heater. The car stayed in Ev the entire trip, I got to work with more remaining charge than on a normal day, and I was pretty decently comfortable in the warm seat and with the warm wheel with no gloves. I was wearing my heavy winter coat. The only issue was windows fogging up and I solved that by cracking the windows for a few seconds. Obviously, the air in the car was very cold, but I wasn't uncomfortable.
Or you could be a totally normal person and run the ICE and not resort to freezing your nice person off and opening and closing the windows constantly.
I've done this as well...Starting from a warm garage, and with the seat heaters on, the car is comfortable without engaging the AC... I would not resort to freezing to save an ounce of gas...But in this case the car was comfortable. Now after being at work all day in sub-freezing temps, I turned the heater on immediately...No consideration of doing anything else. The difficult problem is when I forget to take a coat to work...I'm just fine leaving the house and getting to the office...The short walk from the parking lot to the door is OK without a heavy coat...But the first 5-10 minutes of the trip home really reminds me why I shouldn't leave the coat at home...
I have done this as well...the seat warmer and steering wheel seem to provide all the heat I need when 17 degrees or up. (We had thunder sleet here last night. 1st time I have ever experienced that...weird night.)
As I said, I wasn't uncomfortable (the car was in the garage all night, I had a heavy coat on, and I was in a heated seat with a heated wheel), and I only cracked the windows twice for about 10 seconds each. This was also just an experiment. Best way to learn new things is to try something new. I tried something new in the exact opposite direction here: My first trip through the mountains | PriusChat "When we got in, the battery was at 74% so I decided to put the car in charge mode to generate as much heat as possible by running the engine harder than idle."
I am not a Prime expert, but I thought that heating and cooling was handled by a heat pump. I have one in my house and of course it runs on electricity. I also know that heat pumps are not efficient below something like 30 degrees Fahrenheit as they work by extracting existing heat from the air. Is there a temperature at which the heat pump in the prime no longer comes on?
The heat pump in the Prime is a gas-injected heat pump which keeps it efficient down to around 14°F. Below that, it starts the ICE for heat. That's the point of what I tried.
That. The warmer temp of the batteries + the air temp sensor (which is different than what the battery temp is) allowed it to start in EV. Had the batteries cold-soaked at 9 degrees F all night, it would be instant HV start before you could even reach to turn on any cabin heat, steering wheel heat or seats.
Could be. I did cold soak it outside through the night at 16°F once and it stayed in Ev for that trip. But I haven't tried it colder than that.
Thing is, the batteries will "ride" the warmer air for a while (hours). Let's say it is 25 degrees F in the day (EV works) and it cools down to 12 or 13 at night, then warming back up again for the daytime. There might be a delay in the battery section getting to that 12 degrees, so if may very well still be ~16 or higher at the sensor where it counts. If it stayed at 14-15 for a day or more, then the HV will probably kick on as soon as you hit the power button. On several occasions this winter, the nightly cold soaking (I don't have a usable garage) to temps at around 13-16 have either resulted in instantaneous HV, or a "What the...? Really?" starting and staying in EV mode -- on the way to work (but not if I hit defrost, cabin heat, or the like).
Not could be. Definitely. I don't have a garage. If it's below say 18 degrees out or so the car will run the ICE on startup regardless of anything else.
I did something similar this morning but this time I ran two remote A/C warmup cycles while it was still in the garage. The car was warm and toasty when I got in and I got heat from the heat pump for a little while after I started driving. However, I had to start the ICE this time because it was both colder outside (~6F) and because the near 100% humidity (patchy fog) resulted in much more aggressive window fogging. Two shots with the ICE to defog the windows was sufficient and I still got 115MPG going uphill to work and managed to consume 55% of the battery on the way.
