At my local Supercharger, it costs $0.47 from 8 a.m. to 10 p.m., and just $0.18 from 10 p.m. to 8 a.m. That means if you can wake up a little earlier or go to bed a little bit later, you'll save nearly three times the money. This is not to say that I never charge during peak hours, but I try to save the longer charges for off-peak hours.