On a very cold day (55) I turned on the car while it was plugged in (L1) at about 75% charge. I turned on the climate control in Auto and set it to 77 to simulate a remote control activation request.
The on board energy gauges show about 1.2kW used by the climate control. Plus about 120W for Other Systems. Probably about 1.3KW total. The Miles gauge did not drop so it was probably not pulling anything significant from the batteries.
Glad you consider 55 very cold
43 here this morning.
I noticed something interesting yesterday that tells me the car will use battery power to pre-heat a vehicle even if it is connected to a power source.
Car was charged to 80% overnight on my home L2 Blink EVSE.
6 minutes prior to leaving for work I manually started a pre-heat using carwings. (I left earlier than normal and the timer had not yet kicked in). When I got half way down my driveway I noticed the dash indicated that it would take 10 minutes at 240v to charge the vehicle. Normally that message does not appear until I have driven a mile or more. I used one more bar than normal going to work that day.
I surmised therefore that initially the pre-heat maxes out the heat cycle, probably at close to 6kW, then as the car warms drops down to say 1.5 kW and uses any excess power from the EVSE to top off the battery. Even when connected to an L2 charger it can't deliver the 6kW initial draw given that the charger is rated for 3.3 kW.
On a normal day the pre-heat takes up to 20 minutes prior to my departure, plenty of time to restore the battery to 80% charge during the latter half of the heat cycle if connected to an L2 EVSE.
As for the L1 EVSE, I'm sure that it will suck the battery down initially and will most probably never be able to put it all back by the end of the pre-heat cycle.
2011 Blue SL-e, 132,400 Miles.
Lost 5 Capacity bars
7/18/13 (29,206), 8/25/14 (51,728), 7/12/15 (71.108), 5/12/16 (88,362), 10/17/16 (96,532)
New Battery 12/3/16 (98,956)
2018 Model 3 20,000 Miles.