My wife and I commute together from Brisbane’s northside into the city, so these figures are for two (adult-sized) people on a 19 km round trip. At the end of the ride, the battery has 68% charge remaining.
The charger draws about 370 watts during the main charge (constant current phase), and drops off over the last hour (constant voltage / saturation phase) until it switches off. At rest it draws just 3 watts.
Total charge time from 68% to 100% is about 4 hours, and total power usage is about 1.2KWh.
I pay about 26c/KWh for power. I’m on a solar feed-in plan, which means I pay top price for power from the grid in exchange for a slightly higher tariff for power I return to the grid. If you are not on a solar plan, you might pay less.
1.2KWh x 26c/KWh = 31.2c
For two people with a 19 km commute in city traffic we are paying $1.50/week to run the bike. By way of comparison, it would cost us $80.60/week in bus or train fares; 2 people, 2 trips per day, 5 days/week at $4.03 per trip.