Quick answer
Home charging cost is based on energy drawn from the wall, not just energy added to the battery. Divide battery energy added by charging efficiency to estimate wall energy, then multiply by your electricity rate.
How to work it out
- Estimate how many kWh you are adding to the battery.
- Account for charging losses.
- Multiply wall energy by your home electricity rate.
- For monthly cost, repeat the calculation using your normal weekly or monthly charging volume.
- Use your own utility rate rather than a national average.
Example
Adding 45 kWh to the battery at 90% charging efficiency requires about 50 kWh from the wall. At $0.15/kWh, that charge costs about $7.50.
What can change the answer
Time-of-use rates, charging temperature, battery conditioning and charging level can change the real cost.
Run the calculation with your numbers
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Open EV Home Charging Cost Calculator