I’ve been use Ari_C’s method of preheating for some time now. For my commute, in cold weather, I will start the car manually about an hour before I leave while plugged in to 240v. The heat is set to Eco and Auto.
This accomplishes several things. First, it warms the traction battery up to operating temperature. While the battery does get some heating when plugged in and the car off, I believe it moves to a higher temperature when the car is turned on. I’ll back this up by the fact that when the car is switched on, a pump can be heard winding up, even if the heat is set to off.
Two, at Eco, the car warms up slowly. The 240v can pretty well keep up with the demand, which is not the case with Comfort. Comfort heating will use all of the 240v plus drain some of the traction battery, thus requiring a recharge period to get back to full battery strength, during which time the car is cooling off again. After an hour at Eco, the car is fairly toasty with not just the air, but the seats, the steering wheel, the inside of the windows, etc. all warmed up. The Auto setting allows the air conditioner to come on occasionally to take moisture out of the interior air and help prevent fogging of the windows.
Three, with the Volt running and plugged in, it will gradually charge up the hidden “house on the hill” buffer of the battery, at least in Generation 1. This buffer was designed for people who live on a hill. If they leave home with a “full” battery and then do regenerative braking going down the hill, this hidden buffer gives a place for that energy to go. Turning the car on while plugged in gives the same result. The additional buffer may give one to three more miles of range depending on driving habits and temperature.
When I’m ready to go, I unplug the car, set the heat to Off, but leave the fan on a couple of notches, direct the air to the windshield, and shut off outside air flow. Since the radiator is up to temp, warm air will still flow for several minutes, and since the interior of the car is all warmed up, it will stay comfortable for most of my commute. Keeping air flowing to the windshield helps to keep it clear.
Using this method in cold weather, I’m always able to make my thirty-seven mile commute on battery with at least a few miles of range to spare. I have installed the ERDTT defeat switch so the gas engine never engages in cold weather.
