The cost per mile of home charging is your car’s consumption multiplied by your electricity price — and the consumption figure most drivers use understates what they pay. Your meter bills the energy drawn at the wall. The car reports the energy that reached its battery, and the difference is charging losses. The EV-ACS4005T’s 1.77 in display reports session energy from the wall side, which makes it the right input for a true cost per mile.
Key Takeaways
- Your bill follows wall-side energy; the car’s figure excludes charging losses and understates cost per mile.
- The EV-ACS4005T’s display reports wall-side session energy — the right input for the calculation.
- One week of display totals divided by miles driven, times your tariff, is a measured cost per mile.
- The current setting changes session length only — never the energy a mile needs or the price per kWh.
Two kWh Numbers, and Only One Is Billed
Every session produces two energy figures. The car counts what arrived in the battery. A charger with an energy display counts what left the wall. The wall figure is always the larger one, because some energy is lost as heat in the conversion from AC to DC and in the cable. How large the gap is varies with the car, the temperature and the setup, so no single percentage describes your sessions — which is why measuring beats assuming. For the consumption basics, see how many kWh it takes to charge an EV. One comparison ENERGY STAR does publish: Level 2 charging is on average about 10% more efficient than Level 1. That compares charging levels, not your car — your display gives you your real figure.
Measure Your Real Figure With This Charger
- Charge normally for a week and add up the session energy shown on the display.
- Note the odometer at the start and end of the same period.
- Divide wall-side kWh by miles driven. That is your true consumption per mile, losses included.
- Multiply by the price on your electricity bill. The U.S. average residential price is 18.31 cents per kWh (EIA); your own tariff replaces it.
One Worked Week, as an Example
| Measure | Example figure | What it gives |
|---|---|---|
| Display total for the week | 96 kWh | The energy you were billed for |
| Miles driven in the week | 300 miles | — |
| Wall-side consumption | 0.32 kWh per mile | 96 ÷ 300 |
| Cost per mile at 18.31¢/kWh | About 5.9 cents | 0.32 × 18.31¢ |
| Car-reported consumption, same week | 0.29 kWh per mile | Would suggest about 5.3 cents — and understate the bill |
Every figure in that table is an example, chosen to show the method. Your display and your odometer supply the real ones. The gap between the last two rows is the losses: small per mile, real across a year of driving. For the wider comparison against gasoline, see whether charging an electric car is cheaper than gas.
What the 40 A Setting Changes — and What It Does Not
The current setting chooses speed, nothing else. At 40 A the unit delivers up to 9.6 kW; at 16 A the same energy arrives more slowly. The setting does not change how much energy a mile needs, and it does not change your price per kWh, so it does not change your cost per mile. Choose the setting for the circuit behind the outlet — 40 A belongs on a 50 A breaker under the NEC’s 125% continuous-load rule — and let the car and the tariff decide the per-mile figure.
The EV-ACS4005T as the Meter on Your Wall
The EVDANCE EV-ACS4005T is a 40 A NACS portable charger: 9.6 kW, NEMA 14-50P, 16–40 A adjustable, IP66, a 25 or 28 ft cable — and a 1.77 in display that reports the session’s energy as delivered. That last feature is the one this method runs on: a week of displayed totals turns cost per mile from an estimate into a measurement.
Frequently Asked Questions
Why does the display show more kWh than the car says it received?
Because of charging losses between the wall and the battery. The display counts what left the wall; the car counts what arrived. Your bill is written on the wall figure, which is why the display is the honest input for cost.
Does charging at 16 A make each mile cheaper than charging at 40 A?
No. The car needs the same energy per mile and your tariff is the same; only the session length changes. The setting is chosen for the circuit, not for the price.
My tariff is not 18.31 cents per kWh. Does the method still work?
Yes. The 18.31 cent figure is the EIA’s national residential average, a reference point. Substitute the price from your own bill at the last step and the rest of the method is unchanged.
Related Reading
- How Many kWh Does It Take to Charge an EV?
- Is Charging an Electric Car Cheaper Than Gas?
- How Many kW Is a Level 2 Charger?
