Why Your Home Charging Cost More Than Expected
Home charging often costs more than a simple estimate suggests due to charging inefficiency (some energy is lost as heat during the charging process, meaning more electricity is drawn from the grid than actually ends up stored in the battery), a time-of-use electricity rate that's higher during typical charging hours, or a higher real-world energy consumption rate than the vehicle's official efficiency rating.
This gap between a simple estimate and actual charging cost is common and traceable to a few specific, well-understood factors.
Charging inefficiency
Not all electricity drawn from the grid during charging ends up stored in the battery — some is lost as heat during the conversion and charging process, meaning actual electricity consumed (and paid for) is somewhat higher than the battery's actual stored energy gain alone would suggest, a real but often overlooked factor in a simple cost estimate.
Time-of-use electricity rates
Many utility providers charge different rates depending on time of day, with typical evening charging hours sometimes falling into a higher-cost period — checking whether a specific electricity plan has time-of-use pricing, and adjusting charging schedule if a lower off-peak rate window is available, can meaningfully affect actual charging cost.
Real-world efficiency differing from the official rating
As covered in the true-cost guide, real-world driving conditions (cold weather, aggressive driving, highway speeds) can reduce actual efficiency below the official rating, meaning more energy — and more cost — is needed per mile than the official figure alone would predict.