alt Hacker NewsAs someone who does non-trivial driving: When I switched over, I was floored - that electric bill increase was less in a month than gas was in about three days. And yes, I also have a dedicated 240V/50A circuit, 120/15 is only fine for normal commuters.
In Seattle, we also went from flat 13.4c/kWh to a new variable rate with 8c/kWh available from 12-6am. My electric bill just dropped by about 30%.
What did you switch from and to? Even Tesla's Charging Calculator is far less optimistic than that:
https://www.tesla.com/charging-calculator
"Seattle" may be a critical bit here. The Fed thinks the "U.S. City Average" cost of electricity is far higher than yours:
https://fred.stlouisfed.org/series/APU000072610
Based on how many of my friends followed their first EV purchase with an electrical outlet upgrade - even those with very short commutes - I suspect your "120/15 is only fine for normal commuters" is still a tad optimistic.
EDIT: Re-reading comments here - I'd bet a leading reason to upgrade from 120/15 to 240/50 charging is to get much more of your charging done within the 12am - 6am "lowest rate" time window. Or whatever that window is, locally.