M3 charge timing and pre-conditioning in cold climates with hourly elec $

[j5555]

Heads up for those in cold climates who want to coordinate charge end timing with daily car usage.

In cold climates (such as Chicago) there is great advantage in timing nightly charging to end around the the time you wish to start driving, generally in the morning, as battery is warm and regen loss is limited. However, if you are signed up for hourly electricity pricing--as I am with ComEd, you will find that you are then paying the some of the highest hourly rates for power. Generally speaking, over the past 3-months, the daily peak electric rates occur between 5-8am, and between 4-7pm.

When I switched to hourly pricing in October--for the first two months I didn't pay much attention and was generally charging the car between 6-8am. I soon discovered that I would have been better off with fixed rate pricing. I switched in December back to a 2am charge time and then I'll heat the car for 20-mins or so before driving at 8-9am. I'm back to a slight savings with the hourly rate.

 

[Mikeat00]

Did the math over by Detroit Michigan and decided to stay on fixed rate. The peak rate was too high too justify and the emergency rate they can charge up to 4 hours a day 20 days a year is astronomical ($1 a kWh). The emergency rate would be during the hottest part of the day and kill any savings when I factor in 400 kWh for the car a month at the off peak rate. The saving was minimal and I’m home during peak hours half the time and don’t want to have to watch my usage or be uncomfortable.